2020 NEC FAQ's

[Dennis Alwon]

Frequently Asked Questions

Based on the 2020 National Electrical Code

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I want to mention that although it looks like I posted all of this- well I did- I have to give most of the credit to George Stolz who started these Faq's back in 2005, I believe. I merely copied and posted them and updated some of it. Many members of this community also helped with the research and posts. It is a continuous work in progress so if you see an error please let us know.

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A Brief summary on how to use this thread
In this first post there will be a link to a bunch of Faq's. Click on the link that you like and it will take you to the appropriate post. To return back to the first post start scrolling up and a blue arrow will appear on the right side. Click that and it will take you to the top of that page. If you are not on page 1 then you would have to select page 1 on the left side above the first post


If you post a similar question to the questions that follow, the thread will not be closed because of it: but a link to the appropriate FAQ may be posted. There is usually an avenue to a question that has not been explored, new members arrive daily, and new perspectives are always welcome.

General Questions

• How is the NEC created? How can I propose a change to the NEC? Can anyone propose a change?
• Is there a website at which you can get a free copy of the NEC, either in HTML or PDF format?
• What is the UL White Book, and can I find it online?
• Abbreviations, Etiquette, & Quoting Guide (see also: Quoting multiple members, Quote within a Quote
• How do I add my own pictures into my posts?
• Noteworthy Links
• Quote within a Quote

Branch Circuits, Devices, and Layout Questions

• How many nm cables can you install thru one hole?
• Are antishorts (red-heads) required when using MC cable?
• Is it legal to use a receptacle's screws or back-stab connections for continuity of the circuit, or is pigtailing the conductors required?
• Is pretwisting connections required, when using wirenuts?
• Where are smoke detectors required to be installed, and where do I find this information?
• Arc Fault Circuit Interrupters (AFCIs) from every angle that comes up.
• Ground Fault Circuit Interrupters (GFCIs) from every angle that comes up.
• Is it legal to install a 15A receptacle on a 20A circuit?
• How many receptacles am I permitted to have on a circuit?
• Do I need a light fixture in a habitable room, or just a blank over a box?
• Is it legal to use 14 AWG conductors on a 20A breaker for lighting switchlegs?
• Is there a distance limit for conduit runs, between junction boxes?
• 210.52(A) - Wall Space Questions
• 210.52(B), (C) - Kitchen, Dining and Similar Area Questions
• Does a refrigerator need to be on a single receptacle?
• Can I install a television over a bathtub in a bathroom?
• Is sharing neutrals acceptable and/or code compliant?

Services, Feeders, Panelboards

• The Six-Handle Rule - Services, Feeders to detached structures, etc.
• Detached Garages from every angle that comes up.
• How many cables can I have going through a single connector into a panelboard? How many cables under a staple?

Grounding Code Questions

• Under the 2020 NEC, is an equipotential bonding grid required around a hot tub?
• Am I required to install a Concrete-Encased Electrode if one isn't already present?
• Is a green ground screw required in metal boxes?
• Metal Water Pipes in Detail
• What codes apply when replacing old non-grounding receptacles in an existing structure?
• Am I required to run an equipment grounding conductor to a detached structure?
• Am I required to upsize the Equipment Grounding Conductor when upsizing for voltage drop?
• Am I required to bond the hot and cold supply pipes to the motor of a jetted tub?
• Grounding vs Bonding

Calculation Questions

• How do I calculate voltage drop?
• When is voltage drop required to be considered in the NEC?
• What are the steps to a standard load calculation?
• How do I calculate box fill?
• Is the neutral a current carrying conductor? How do I apply 310.15(B)(4)?
• How do I calculate residential range loads?

The Taboo Questions that will be promptly closed, due to exhaustion of the topic (or because of Forum Rules):

• Do you install three-ways and fourways so the load is off when the switches are all down?
• Should a receptacle be installed with its ground connection point up or down?
• Should I join or avoid a Union shop?

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If you notice a technical error, have a question you believe belongs here, or have a different opinion on a topic addressed by the FAQs that you feel should be included, feel free to start a thread on it with "FAQ" in the title. Or, you can send Dennis Alwon a PM or post feedback in this thread if it's a small issue.

If you do not understand an answer in the FAQ, feel free to start a thread on any of the topics (except for the taboo topics mentioned above).

 

[Dennis Alwon]

The NEC Cycle Process

The NEC Cycle Process

• How is the NEC created? How can I propose a change to the NEC? Can anyone propose a change?

The NFPA standards development process encourages public participation in the development of its standards. All NFPA standards are revised and updated every three to five years, in revision cycles that begin twice each year. Normally a standard’s cycle takes approximately two years to complete. Each revision cycle proceeds according to a published schedule which includes final dates for each stage in the standards development process. The four fundamental steps in the NFPA standards development process are:

1. Public Input
2. Public Comment
3. NFPA Technical Meeting (Tech Session)
4. Standards Council Action (Appeals and Issuance of Standard)

The NFPA Manual of Style (basically, the rules for writing rules) can be found at this link.

• Is there a website at which you can get a free copy of the NEC, either in HTML or PDF format?

The NFPA made the NEC accessible, without cost, directly from their web site. The information is available as a "read only" page. It is not possible to copy, print, or otherwise duplicate what is given to you for free. Access requires you to agree to their terms and conditions. Here is the page (copy this web address to your browser's address bar): nfpa.org then select free access. You may have to setup an account but it is free also. This version has no "search" feature. If for example you want to find the rule about AFCI protection, you cannot search for that term. You have to look at the table of contents, and then read page by page until you find what you want.

 

[Dennis Alwon]

Grounds Up or Down?

• Should a receptacle be installed with its ground connection point up or down?

The NEC does not address this question. Both configurations are equally acceptable. It is a matter of choice, and the choice can be made by the designer, the installer, or the owner. There may be some aesthetic advantages in being consistent throughout a given project, but even that is not a code requirement. There have been reasonable arguments made in favor of “ground up.” There have been reasonable arguments made in favor of “ground down.” However, not one of the arguments is any more compelling than any other.

 

[Dennis Alwon]

Is pigtailing a receptacle required?

Is pigtailing a receptacle required?

• Is it legal to use a receptacle’s screws or back-stab connections for continuity of the circuit, or is pigtailing the conductors required?

First, the NEC does require certain conductors to be "pigtailed", to not depend on the device to carry the current flowing through the entire circuit. For grounded (neutral) conductors in a multiwire branch circuit, pigtailing is required, see 300.13(B).

For equipment grounding conductors, there is a similar requirement in all circumstances. See 250.148.

The UL listing information for receptacles can be found by clicking here. Here is an excerpt from that information:

Screwless terminal connectors of the conductor push-in type (also known as "push-in-terminals") are restricted to 15 A branch circuits and are for connection with 14 AWG solid copper wire only. They are not intended for use with aluminum or copper-clad aluminum wire, 14 AWG stranded copper wire, or 12 AWG solid or stranded copper wire.

Single and duplex receptacles rated 15 and 20 A that are provided with more than one set of terminals for the connection of line and neutral conductors have been investigated to feed branch circuit conductors connected to other outlets on a multi-outlet branch circuit, as follows:

• Back wire (screw actuated clamp type) terminations with multiple wire access holes used concurrently to terminate more than one conductor
• Side wire (binding screw) terminals used concurrently with their respective push-in (screwless) terminations to terminate more than one conductor

Single and duplex receptacles rated 15 and 20 A that are provided with more than one set of terminals for the connection of line and neutral conductors have not been investigated to feed branch circuit conductors connected to other outlets on a multi-outlet branch circuit, as follows:

• Side wire (binding screw) terminal with its associated back wire (screw actuated clamp type) terminal
• Multiple conductors under a single binding screw
• Multiple conductors in a single back wire hole

Duplex receptacles rated 15 and 20 A that are provided with break off tabs may have those tabs removed so that the two receptacles may be wired in a multi-wire branch circuit.

"Not investigated" is not the same as "not permitted", it means the AHJ must make the decision on approval.

In general, it is considered a superior practice to pigtail all conductors, but many don't and it is not required.

Related Thread

15 Amp devices in a 20 Amp circuit -- Started by kbsparky, Nov. 2005

 

[Dennis Alwon]

Smoke Detectors

Smoke Detectors

• Where are smoke detectors required to be installed, and where do I find this information?

NFPA 72 and various building codes have different specific requirements.

Here is a rough summary, however many areas have adopted their own rules

• One in each bedroom (to wake people up).
• One on each level, including basement.
• A smoke in a basement shall be on the ceiling, near the entry to the stairs.
• One outside each sleeping area, within "XX" feet of the door (that distance is in the smoke detector manual) to any sleeping area. If the hallway is closed off from the sleeping and living areas by doors, then smokes are required on both the living and hallway sides of the door. In most cases this would be a smoke/carbon detector
• When a door is installed in a stairway, smoke rising up the stairwell cannot be obstructed from a detector by the door.
• One in the living area of a guest suite.
• No closer than 3' to any cold air return or supply, or ceiling fan. Nuisance alarms due to dust attraction are common when this is done, and the sensitivity can diminish.
• No closer than 4" and no farther than 3' to peak of vaulted ceiling. Smoke rolls in corners, bypassing detector.
• No farther than 3' from peak of vaulted ceiling.
• No closer than 4" from wall on a flat ceiling.
• No closer than 4" from ceiling and no farther than 12", when wall mounted.
• Ambient temperature cannot exceed 100 F, or below 40 F, as in attics and garages.
• Interconnection of detectors is required.
• Per NEC 210.12, AFCI protection required. Per NFPA 72 11.6.3(7), if the smoke is supplied by an AFCI, then battery backup is required. By 11.6.4(1), the smoke must audibly report a low battery condition.
• The instruction booklet supplied with the smoke detector is required to be provided to the occupant. (72 11.8.4(1).)
• Smokes should be replaced every ten years. (72 11.8.5(b).)

Many smoke detectors come with instructions that mirror NFPA 72's requirements, so they could also be considered a 110.3(B) listing issue, if NFPA 72 has not been adopted in your area.

A free online viewable copy of NFPA 72, is available by clicking on this link (Click "I agree" to see the read-only document).

 

[Dennis Alwon]

AFCI's

All About AFCI's​

Click here for a link to the FAQs on AFCIs.

The requirements for AFCIs can be found in 210.12:

210.12 Arc-Fault Circuit-Interrupter Protection.
(A) Definition: Arc-Fault Circuit Interrupter. An arc-fault circuit interrupter is a device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc fault is detected.

210.12(A) Dwelling Units.
All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas shall be protected by any of the means described in 210.12(A)(1) through (6):

This requirement covers receptacle outlets, lighting outlets, and outlets for other equipment such as smoke detectors. Bear in mind, local jurisdictions have the authority to amend the NEC as they adopt it, so local enforcement may vary.

Note that Article 760 fire alarm systems are not allowed to be supplied by GFCI or AFCI. This is not usually relevant to dwelling units, because smoke detectors are not Article 760 fire alarm systems.

Old Work:

210.12(D) Branch Circuit Extensions or Modifications — Dwelling Units, Dormitory Units, and Guest Rooms and Guest Suites.
Where branch circuit wiring for any of the areas specified in 210.12(A), (B), or (C) is modified, replaced, or extended, the branch circuit shall be protected by one of the following:

1. (1)
   By any of the means described in 210.12(A)(1) through (A)(6)
2. (2)
   A listed outlet branch-circuit-type AFCI located at the first receptacle outlet of the existing branch circuit

Exception: AFCI protection shall not be required where the extension of the existing branch circuit conductors is not more than 1.8 m (6 ft) and does not include any additional outlets or devices, other than splicing devices. This measurement shall not include the conductors inside an enclosure, cabinet, or junction box.

You determine what is new: if it's a new receptacle outlet, then the circuit supplying this new receptacle outlet is to be AFCI protected. If other receptacles are already existing in the same room, on a different circuit, then that existing circuit would not require AFCI protection.

If you install a new outlet in an existing dwelling unit bedroom, then technically you would need to provide AFCI protection for the entire circuit supplying that new outlet. This can pose problems for an installer because there is limited (or no) availability of AFCI breakers for older existing panelboards. Some jurisdictions do require the protection regardless of the existing equipment, so a solution would be to install another panelboard in line to get AFCI protection on the new outlet.

Some jurisdictions in the past require that AFCI protection be added if you change the service or the panelboard inside. That is not the intent of the NEC and section 210.12(D) was written specifically for panel changes.

Troubleshooting: Most AFCI Branch/Feeder circuit breakers come equipped with 30-50mA GFPE (GE has eliminated GFPE entirely from their product). Usually, a "bootleg neutral" is the cause for nuisance tripping under load, and can be detected by normal troubleshooting methods.

What is the difference between a "branch/feeder type" and a "combination type" AFCI?
Both types examine the waveform signature of the loads they supply, and compare the signatures supplied to signatures they are designed to interrupt. An arcing fault is usually the result of a bad connection, or damaged wiring/cords, which creates a high-resistance connection ("glowing connection") that heats up and combusts surrounding material.

The branch/feeder type AFCI was the original style of AFCI that was first introduced to the market. They look for arcing faults in loads exceeding 75 amps, which greatly limited their ability to discover and disconnect arcing faults. Most of the nuisance-tripping issues that occurred when the device was introduced was a result of the built-in ground fault protection (GFPE) detecting bootleg neutrals (an EGC carrying neutral current inadvertently).

Given the low amperage of most household appliances, and the high threshold for the branch feeder AFCI, there is virtually no protection beyond the outlet when using a branch/feeder AFCI.

The combination-type AFCI was required starting 01/01/2008, by the 2005 cycle of the NEC. It examines all loads exceeding 5 amps for arcing faults. This breaker will sense series as well as parallel faults.

The combination type will be able to offer protection to cord-and-plug connected loads even through cords, according to the manufacturers.

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al hildenbrand 224 - charlie b 109 - jwelectric 85 - LarryFine 66 - marc deschenes 48 - allenwayne 38 - jeff43222 31 - iwire 31 - electric_instructor 28 - peter d 25 - roger 24 - don_resqcapt19 15 - electricmanscott 11 - georgestolz 9 - jimwalker 6 - sandsnow 5 - sparky_magoo 4 - dillon3c 2 - ronaldrc 2 - paul 2 - magoo66 2 - hbiss 2 - mark32 2 - tkirk911 1 - macmikeman 1 - JES2727 1 - aelectricalman 1 - pierre 1 - realboss 1 - steve66 1 - busman 1 - petersonra 1 - j_erickson 1 - ryan_618 1

Related Link--
Evolution of Arc-Fault Circuit Interrupter and the National Electrical Code

The guilty are listed above with their counts.

​

 

[Dennis Alwon]

GFCI's / GFPE

All About GFCI’s​

GFCI's are intended to protect people from electrical shock in many different situations.

The main requirements for GFCIs can be found in 210.8. There are additional requirements scattered throughout the NEC for various specific occupancies and equipment, such as elevators, swimming pools, temporary installations, etc.

Key Note is that for residence all single phase receptacle circuits 125V-250V in the locations listed need gfci. In Non dwelling it include 3 phase up to 100 amp in those areas listed. The areas listed have been expanded so check your section

All gfci devices must be readily accessible.

A big change here is this note which eliminated the words door or doorway. Now if there is a receptacle within 6' of a bathroom, even if there is a door than that receptacle must be gfci protected.

For the purposes of this section, when determining the distance from receptacles the distance shall be measured as the shortest path the supply cord of an appliance connected to the receptacle would follow without piercing a floor, wall, ceiling, or fixed barrier, or the shortest path without passing through a window.

210.8(A) Dwelling Units.
All 125-volt through 250-volt receptacles installed in the locations specified in 210.8(A)(1) through (A)⁠(11) and supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel.

210.8(B) Other Than Dwelling Units.
All 125-volt through 250-volt receptacles supplied by single-phase branch circuits rated 150 volts or less to ground, 50 amperes or less, and all receptacles supplied by three-phase branch circuits rated 150 volts or less to ground, 100 amperes or less, installed in the locations specified in 210.8(B)(1) through (B)(12) shall have ground-fault circuit-interrupter protection for personnel.

• When was GFCI protection required for __________ ?

Click here to see when GFCI protection was required by various cycles of the code, compiled by Jerry Peck for Mike Holt.

• How do GFCI's work? Do they require an EGC to work?

GFCI's have coils inside them that continuously measure the current leaving the GFCI on the ungrounded (hot) conductor, and measure the current returning on the neutral conductor. If more current leaves on the ungrounded conductor than returns on the neutral conductor, then the GFCI will trip. GFCI's are set to trip when the imbalance between the conductors is from 4-6 milliamps.

They do not trip under a short circuit, because in a short circuit, all current is still travelling along the normally current-carrying conductors.

Since GFCI's monitor the ungrounded and grounded conductors of a circuit, they do not use the EGC of the circuit for any purpose. That is why GFCI's are permitted to replace two-wire non-grounding receptacles in existing structures. Click here for the FAQ discussing this.

GFPE (Ground-Fault Protection of Equipment)​

GFCI is different than GFPE, in that GFPE is designed to minimize damage to equipment during a ground fault. The requirements for GFPE can be found in various locations in the NEC. Here's an excerpt from the index of the NEC:

Ground-fault protection
Deicing and snow-melting equipment, 426.28
Emergency systems, not required, 700.26
Equipment, 215.10, 240.13
Definition, Art. 100–I
Health care facilities, 517.17
Personnel. see Ground-fault circuit interrupters
Pipeline heaters, 427.22
Service disconnecting means, 230.95
Solar photovoltaic systems, 690.5

Related links:

Gfci 2020 Nec - started by Dennis Alwon 10/2019
How GFCI's Work

 

[Dennis Alwon]

210.21(b)(3)

210.21(b)(3)

? Is it legal to install a 15A receptacle on a 20A circuit?​

​

Yes, provided that it is not an individual branch circuit. The requirements are found in 210.21.​

210.21(B)(1) states that a single receptacle on an individual branch circuit shall have a rating equal to or greater than the rating of the branch circuit.

210.21(B)(3) states that when connected to a branch circuit supplying two or more receptacles or outlets, the receptacles shall conform to Table 210.21(B)(3).

A duplex receptacle is 2 outlets not one. This is a single receptacle

Note that a circuit rating must be chosen first, and then a suitable receptacle rating can be determined. The table does not work in reverse, and this is a common misunderstanding.

 

[Dennis Alwon]

How many NM cables can I have going through a single connector into a panelboard? How many cables under a staple?​

​

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It depends upon the listing of the connector/staple. Most connectors are listed to have a maximum of two cables per connector. Most staples are listed for two cables, but some are listed for one. Here is an example of Arlington's plastic push in connectors and what cable combination you can use with them.

Our new 1/2" NM942 holds one or two cables, in two separate openings: • One or two 12/2 • One or two 14/2, or one 12/2 and one 14/2

Section 110.3(B) requires listed equipment and material be used according to it's listing.

Some staples are unlisted, so it falls on the AHJ to approve/disapprove of the installation (90.4). Most people feel that three cables under a staple is acceptable.

How many NMs under a staple, with code references - Mar 2007.
Stacking Runs of Romex - Feb 2007.
Plastic Vs. Metal Staples - Mar 2005.
Stak-Its - Feb 2005.

 

[Dennis Alwon]

How many receptacles per circuit?

How many receptacles per circuit?

? How many receptacles am I permitted to have on a circuit?​

​

In 220.10, it states that branch-circuit loads shall be calculated according to the requirements of 220.12, 220.14, and 220.16.

220.14(J) states that the receptacles in a dwelling unit are already included in the "Lighting and Receptacle Load" specified in 220.12. From this, most users of the NEC agree that there is no limit in the NEC for the number of receptacles that can be placed on a circuit in a dwelling.

However, most users of the NEC view this as proof that in a commercial setting, you must assume that there will be 180VA per receptacle, per 220.14(I). Therefore, they draw the conclusion that you may not have more than 13 receptacles on a 20A branch circuit (assuming that there are no continuous loads on the branch circuit at all.) This is the popular textbook perspective on the issue of how many receptacles are allowed on a circuit in a commercial setting.

However, there are some users of the NEC who believe that the provisions of Article 220 are to be used solely for determining the "calculated load for the service", and not for the "load to be served". (George's note: I consider this to be a minority opinion but worthy of mention. In one of the threads below (Number of Receptacles), a poll showed 75% of members who voted believe there is a 180VA limit in commercial. )

Bear in mind, the NEC is a minimum standard and it's scope makes clear that we are free to design and install at an above-code level. (90.1). Specifications developed by an engineer may be replied upon by the AHJ for final approval of a project, and the specs may also be used as a contract standard as well.

Related Threads:
Max Number of Receps per Circuit - Mar 2014. Started by Greenjourneyman
Outlets Per Breaker - May 2005. Started by rmatc4, currently ranks #14 all time in the NEC forum at 167 posts.
Number of Receptacles - Jun 2007. Started by Jamesco, still in progress as of 2/12/2018.

____________________________________________________________
____________________________________________________________​

Is there anywhere in a dwelling unit where you are restricted to the number of receptacles you put in?

No.

Bob's answer is correct only with respect to the electrical codes.

Various other building codes clearly set limits on the number of receptacles which you may put in. For example, fenestration requirements dictate that at least some portion of the wall area be used for windows, similarly egress requirements dictate space dedicated for doors. (Though I suppose that you could mount receptacles upon the doors.)

The effect of device boxes on any required thermal insulation would need to be considered, and large numbers of device boxes on firewalls will require special design.

-Jon

 

[Dennis Alwon]

Lighting Outlet Requirements

• 
  
• Do I need a light fixture in a habitable room, or just a blank over a box?

210.70 lays out requirements for lighting outlets in different situations. In 210.70(A)(1), the requirements for lighting outlets in habitable rooms is outlined.

The key is, the primary term used is lighting outlet. A lighting outlet is defined in Article 100 of the NEC as:

Lighting Outlet. An outlet intended for the direct connection of a lampholder or luminaire

So, essentially, the box that a luminaire is attached to is the lighting outlet. Therefore, the most commonly held belief is that a box with a blank is perfectly acceptable for meeting the requirements of the NEC. Here are some Code-Making-Panel Comments regarding this section, from the 2008 Report on Proposals:

Proposal 2-251: The objective of the NEC is to provide the requirement for the lighting outlet. The requirements specific to illumination are in the building code.

Proposal 2-252: The location and number of switches is a design requirement that is determined by the designer, user or installer. The panel disagrees with the submitter’s example in the substantiation relative to the switch at the top of the basement stairs. If there are six risers or more, a switch is required at the top and bottom of the stairs.

Proposal 2-253: Closets are not intended to be covered in the present rule (210.70(A)(3). The submitter has not substantiated a requirement for a lighting outlet in every closet.

The requirement for illumination is believed by the CMP to be dictated by the building code. However, to date no one (to my knowledge) has come forward with IBC/UBC requirements to confirm this. It also would not mesh with the allowances of a switched receptacle in lieu of a lighting outlet as permitted by the exceptions.

A big change in the 2020 Nec is requirement for a wall switch control to be located near the room that the switch controls

210.70(A)(1) Habitable Rooms.
At least one lighting outlet controlled by a listed wall-mounted control device shall be installed in every habitable room, kitchen, and bathroom. The wall-mounted control device shall be located near an entrance to the room on a wall.
Exception No. 1: In other than kitchens and bathrooms, one or more receptacles controlled by a listed wall-mounted control device shall be permitted in lieu of lighting outlets.
Exception No. 2: Lighting outlets shall be permitted to be controlled by occupancy sensors that are (1) in addition to listed wall-mounted control devices or (2) located at a customary wall switch location and equipped with a manual override that will allow the sensor to function as a wall switch

Related threads:
Habitable Rooms - Lighting Outlet, Feb 2007. Started by MrMark, with 6 pages as of this addition.
Section 210.70 Change- Jan 2020, started by Dennis Alwon

 

[Dennis Alwon]

The Six Handle Rule

The Six Handle Rule

The Six-Handle Rule
Services, Feeders to detached structures, etc.
​

The rules for the number of switches allowed to disconnect all ungrounded conductors of a structure are given in different locations depending on the application.

For detached buildings that are fed from another building, the rules are given in Part II of Article 225. Section 225.33(A) also requires no more than six handles to a structure.

In the past, we were allowed to have 6 breakers in one panel to disconnect a service, however the buss bar was still energized when all the breakers were turned off and accidents have occurred because of it. Now the 2020 NEC requires one main disconnect in each service panel with a maximum of 6 service panels.

Grounding requirements for services are found in Article 250, Parts I and III.

Bonding and Grounding requirements for detached structures are found in 250.32, and are discussed in detail in this FAQ.

Related threads:
230.70 Disconnect Rule-- started by srv52761 on 1/25/2020

 

[Dennis Alwon]

Detached Garages

Detached Garages

Detached Garages
​

There are many different desired designs for detached buildings, perhaps as many as people who build and wire them. For clarity, I will put some examples up and explain each example.

Example #1: A small outbuilding calls for a 15A circuit for lighting, and a 15A circuit for a receptacle. A multiwire branch circuit is selected, a 12-3 UF cable. In this case, no grounding electrode system is required to be connected to the electrical system of the detached structure.

According to 250.32(A), exception, no grounding electrode system is required for a single circuit, and the multiwire branch circuit is considered one circuit. 225.33 requires a disconnecting means for all ungrounded conductors supplying the building. The EGC in the UF cable is the effective ground fault clearing path required by 250.4

Example #2: In this scenario a detached garage needs more than 2 circuits which means there must be a sub panel installed at the garage which must have either a main breaker or it must follow the 6 disconnect rule. Grounding electrodes must be installed and a feeder must have an equipment grounding conductor. The grounding electrode conductor from the electrode(s) must be connected to the equipment grounding conductor and the neutral must be isolated from the panel enclosure.

Please note that the grounding electrodes are for the purposes outlined in 250.4(A)(1) only, and are not a ground-fault current return path! They do nothing when a energized conductor touches the normally non-current-carrying metal of the equipment grounding system.

Also see The Six-Handle Rule FAQ .

Related Links:

 

[Dennis Alwon]

Lighting fixture (luminaire) taps?

Lighting fixture (luminaire) taps?

• Is it legal to use 14 AWG conductors on a 20A breaker for lighting switchlegs?

No. All parts of a 20A circuit for lighting are included in 240.4(D), which includes conductors between a switch and a luminaire.

 

[Dennis Alwon]

Distance Limit for conduit runs

Distance Limit for conduit runs

• Is there a distance limit for conduit runs, between junction boxes?

No. However, all conduit/tubing wiring methods are restricted to no more than 360 degrees of bend between pull boxes or junction points. See xxx.26 (as in, 358.26 for EMT, etc).

 

[Dennis Alwon]

210.52(a)

210.52(a)

210.52(A) – Wall Space Questions​

• Do I have to include wall space that is exclusively behind doorswings when laying out receptacles?

Yes, in dwelling units. Mobile Homes have different (but similar) rules in 550.13, and in mobiles, the space behind the doorswing is permitted to be excluded by 550.13(G).

A receptacle behind a doorswing is a natural space for a user to plug in appliances that move around the dwelling unit, such as vacuum cleaners.

• Are foyers included in 250.52(A)?

Foyers have generated some discussion. Some see them as a hallway, others as a habitable room. Given the difficult language of this section, it has been unclear as to whether some "similar areas" were intended to be covered by the wall-space requirements.

However, in the 2008 code cycle some proposals were submitted that cleared up some confusion about the CMP's intent, even if they were rejected. Proposal 2-195 suggested including foyers in the requirements of 210.52(A), and the panel replied, "The submitter ’s concern about the receptacle outlet requirements in foyer areas is already addressed in 210.52(H)."

The panel believes that a foyer is a hallway.

• Can a receptacle serving a kitchen countertop also serve as the wall space receptacle for the wall space next to the countertop, sharing the same wall?

No. 210.52(A)(1) states that no point measured along the floor line in any wall space be more than 6 feet from a receptacle. If the receptacle doing the serving is not contained in that wall space then as far as this section is concerned, there is no receptacle present.

Further, CMP statements on proposals to this section confirm the idea that they are very aware of potential damage to cords that go over the edge of a counter, which they bear in mind as the amend the sections each cycle. This is explored further in the kitchen FAQ.

 

[Dennis Alwon]

210.52(B), (C) – Kitchen, Dining and Similar Area Questions​

Foreword: 210.52(B) and (C) tread deeper into design than most sections of the NEC. As a result, it can be confusing to determine the right course of action when dealing with some custom kitchens that are not designed with the electrician in mind. Designers take a form of sadistic glee in designing kitchens that are attractive to the eye and bear innovative ideas that make applying the NEC to them a somewhat arduous task. I will attempt to provide a number of links to odd kitchens presented in different threads, to give you something to work with in coming to your own conclusions. -George

​

210.52(B)(1): Requires all wall, counter, and fridge receptacles in these areas to be on the two or more required SABCs.
Exception 1 permits a receptacle installed to replace a lighting outlet, to be supplied from a lighting circuit.
Exception 2 permits the receptacle for a fridge to be on it's own individual branch circuit 15A or greater. So the fridge is either on an SABC or on it's own, two options.

210.52(B)(2): Forbids us from using the SABCs for other outlets.
Exception 1 allows an SABC to serve a receptacle for a wall clock.
Exception 2 allows an SABC to serve small loads on fixed gas cooking appliances.
These two exceptions make it clear that receptacles behind fixed (or cumbersome) appliances are not "wall receptacles". They are receptacles for specific appliances.

210.52(B)(3): The group of receptacles serving countertops in a kitchen shall be served by two SABCs. (Each receptacle is served by one; the group of receptacles by no less than two).

210.52(C): Did you ever notice counters in dining rooms are to comply with the 2'/4' spacing rules, just like kitchens?

210.52(C)(1): "Wall Counter Space" is defined. This is different than "Wall Space".

210.52(C)(2): Island Countertop Spaces. At least one receptacle shall be installed at each island countertop space with a long dimension
of 600 mm (24 in.) or greater and a short dimension of 300 mm (12 in.) or greater

210.52(C)(3): This section of the Nec seems to go thru changes every code cycle. The one change is that the connected perpendicular wall was added to define that a peninsula is measured from the wall not from the cabinet it may attach to.

210.52(C)(4): This section makes it clear that sinks, ranges and cooktops separate counters for the purposes of this section.

Note that appliance garages are not listed. Proposals have been submitted to permit an appliance garage to separate counter spaces, and have been rejected on the premise that there is usually counter space in front of the appliance garage large enough to facilitate food preparation.

However, in all but the same breath, they have rejected proposals to require counter-spacing requirements to be observed inside appliance garages. As in, the receptacle inside the appliance garage should not be considered serving the counter space in front of the appliance garage.

The panel has never clarified (to my knowledge or satisfaction) how exactly we are to serve this counter space.

In practice, generally the space in front of an appliance garage is considered served by receptacles with the garage. In general, GFCI protection seems to be required for these receptacles. Given the confusion, it would be good to get the AHJ's input before setting any design into stone, if it is questionable.

In my opinion, the space in front of an appliance garage is not wall counter space, as it backs up to cabinetry and not a wall. Therefore, it should be considered a break in the counterspace and also have the 2'/4' rule enforced inside the garage as well. However, the words at this point are not there.

210.52(C)(5): This section requires all receptacles serving counter spaces to be above the counter within 20" of the countertop. Only on peninsulas and island are receptacles allowed below the countertop due to the damage of a cord on the edge of the countertop. Or a child pulling on an appliance plugged in.

Related links:

Kitchens and Islands-- Oct, 2019 Started by Dennis Alwon
Here we go again: Hallway or Not? - May 2007. Started by Dennis Alwon
Appliance Garages on SABCs - Oct 2006. Started by Volt102, with 65 replies. "Are appliance garages required, permitted, or prohibited to be on the SABCs? GFCI protected?"
Can I put a microwave on a SABC - Feb 2005. Started by ethwinfir, with 31 replies.
Switched Dining Room Outlet? - Mar 2005. Started by davedottcom, with 513 replies. An exhausting odyssey through the interrelationship between 210.52 and 210.70. Pack a lunch.
Undercabinet Lights - Apr 2005. Started by Electrofelon, with 277 replies. "Can a luminaire be plugged into a countertop receptacle?" How innocent a beginning for such a bloodletting.
Since you guys are so smart... - Apr 2005. Started by Electricmanscott, with 35 replies. Addressed an odd kitchen with difficult customer requests surrounding an appliance garage.

For more related threads, search for the term "210.52". As of this writing, it comes up with 151 threads, most of which are dealing with some aspect of complying with the NEC in kitchens and similar areas.

 

[Dennis Alwon]

• Can I install a television over a bathtub in a bathroom?

Yes, but the receptacle for the television cannot be over the tub space (406.8(C)). Regardless of receptacle location, if in the bathroom, it requires GFCI protection (no exceptions) 210.8(A)(1).

Related Links:
Question posted 1/18/2020
Question posted 03/07/2016

 

[Dennis Alwon]

ABBREVIATIONS

AFCI - Arc Fault Circuit Interrupter
AHJ - Authority Having Jurisdiction
AHU - Air Handling Unit (as in, Air Conditioning)
AIC - Amps Interrupting Capability
AC - usually Air Conditioning; also Armored Cable, Alternating Current
AFAIK - As far as I know
AFAICT - As far as I can tell
BTW - By The Way
CB - Circuit Breaker
CMP - Code Making Panel
DIY - Do It Yourself
EC - Electrical Contractor
EGC - Equipment Grounding Conductor
ESI - Electricians Success International - an organization
ESS- Energy Storage System
FAP (FACP) - Fire Alarm (Control) Panel
FLA - Full Load Amps
FWIW - For What It's Worth
GC - General Contractor
GEC - Grounding Electrode Conductor
GES - Grounding Electrode System
GFCI - Ground Fault Circuit Interrupter
GFI - Ground Fault Interrupter (technically GFCI)
HI - Home Inspector
HO - Home Owner
HVAC - Heating, Ventilation, and Air Conditioning
IIRC - If I Recall Correctly
IMHO - In My Humble Opinion
IMO - In My Opinion (used by those who are not humble)
IOW - In Other Words
KVA - kilo-volt-amps
KW - kilo-watt
LABCPB - Lighting & Appliance Branch Circuit Panelboard (408.34)
LMAO - (I'll not translate this one)
LOL - Laughing Out Loud
LOTO - Lock Out Tag Out
LRA - Locked Rotor Amps
MCB - Main Circuit Breaker
MCC - Motor Control Center
MDP - Main Distribution Panelboard
MID - Microgrid Interconnection Device
MLO - Main Lugs Only
MWBC - Multiwire Branch Circuit (see definition in Article 100)
NEC - National Electrical Code
NECH - NEC Handbook
NEMA = National Electrical Manufacturers' Association
NETA - National Electrical Testing Association
NFPA - National Fire Protection Association
OCP - Overcurrent Protection
OCPD - Overcurrent Protection Device
OP - Original Poster (i.e., the person who started the thread)
OTOH - On the Other Hand
POCO - Power Company
PPE - Personal Protection Equipment
RCI - Residual Current Interrupter (like GFPE, but European)
TOU- Time of Use
RTU - Roof Top Unit (as in, air conditioning)
ROFL - Rolling On Floor Laughing
SA (SABC) - Small Appliance (as in "SA Branch Circuit")
SDS - Separately Derived System
TLDR - Too Long, Didn't Read.
UL - Underwriter's Laboratory
URD - A cable assembly with no outer sheath, composed of three or more conductors of USE for direct burial.
USE - See Article 338.
VFD- Variable Frequency Drive (could be Volunteer Fire Department too)
WTG - Way to go
List compiled by Charlie Beck, with help from others.

 

[Dennis Alwon]

Equipotential Bonding & Hot Tubs

Equipotential Bonding & Hot Tubs

• Under the 2017 NEC, is an equipotential bonding grid required around a hot tub?

Yes, it is. 680.42 states that outdoor installations shall comply with Parts I and II, except as amended by 680.42's subsections. There was an addendum in the 2014 code and added in the 2017 Nec that has an exception. If you can comply with 680.42(B) then you would not need the equipotential bonding.

Enforcement is not widespread on the issue of whether or not an equipotential bonding is needed if the tub was sitting on a deck. Many believe that no equipotential bonding is needed but the NEC does not give exception for decks unless the tub installation meets 680.42(B)

What is subgrade? Imo, it is the area in the dirt below all the gravel, concrete, tile etc. The equipotential bonding is supposed to carry any ground voltage and make everything in the pool area at that same potential. It may seem odd to take ground voltage (stray voltage) and put that voltage on the metal parts of the pool or hot tub.

Indoor Hot tubs that are mounted above a finished floor is exempt from the equipotential bonding.

Related Links: