Frequently Asked 2005 NEC Questions

Status
Not open for further replies.

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
  • Is pretwisting conductors required when using wirenuts?

This question is not answered in the NEC, it is a product listing question. Products are required to be used in accordance with their listing by 110.3(B).

Most (if not all) wirenuts are listed for use as follows: Pretwisting the conductors is not necessary, but not prohibited - as long as the conductors are twisted once the wirenut is in place, then the manufacturer's instructions have been followed and the code is satisfied. If the connection is not twisted, then there is a 110.3(B) violation when using most (if not all) brands of wirenuts.

That said, most electricians will agree that a pretwisted connection is the most professional method, as it allows the installer to see without a doubt that the connection is tight before installing the wirenut.

But pre-twisters and post-twisters are all welcome here. :)
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
  • Does a receptacle behind a fridge need to be a single receptacle?
This question has many different codes that inspire it, and they all address different aspects:
  1. 210.52(B)(1) & (2) - If a duplex is installed, what's the other receptacle doing, if it's on the Small Appliance Branch Circuit (SABC)? Isn't this second receptacle behind the fridge prohibited?
  2. 210.52(B)(1), exception 2 - If a duplex receptacle is installed, isn't this no longer an 'individual branch circuit', since there are two receptacles and one appliance?
  3. 210.8(A)(6) - If the receptacle for the fridge is right next to the counter, and easily used from the countertop, does it need to be a single receptacle or GFCI protected?
  4. 210.8(A)(7) - If the receptacle for the fridge is within 6' of a wet-bar sink, wouldn't it need to be a single receptacle or be GFCI protected?
I'll just take each as I've laid them out:
  1. 210.52(B)(1) requires the receptacle outlets for walls, counters and refrigerators to be supplied from the SABCs. A receptacle outlet is an outlet box containing one or more receptacles; a duplex receptacle in an outlet box behind the fridge meets this requirement.
  2. No: an individual branch circuit supplies only one appliance by the definition in Article 100. The definition does not discuss the number of receptacles supplied by the circuit, but the loads; therefore, a receptacle outlet supplying one appliance is an individual branch circuit.
  3. No: A receptacle has to be installed over the countertop to serve the countertop (210.52(C)(5)). If it is installed behind the fridge, to serve the fridge, then 210.8(A)(6) does not apply to it. Further, there are no exceptions to 210.8(A)(6), all receptacles installed to serve the countertop are to be GFCI protected. Installing a single receptacle for a single appliance does not matter, as it does in basements and garages.
  4. GFCI protection would be required whether the receptacle is a single or a duplex, as there are no exceptions for laundry, utility, and wet bar sinks as there are for basements and garages. Please note that a kitchen sink is not a wet bar sink by common interpretation, but wet bar sinks (or kitchen sinks) are not defined in the NEC. A refrigerator receptacle 1' from a sink in a kitchen does not require GFCI protection, but the same situation at a wet bar does.
Don't ask me to make sense of it, I'm just repeating what I believe. :D
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
  • Is sharing neutrals an acceptable practice? Is it code compliant?
Sharing neutrals is perfectly legal in most situations. The NEC term for several ungrounded conductors sharing a neutral is a "multiwire branch circuit." The definition is in Article 100. The key is, a multiwire branch circuit has a voltage between all the conductors of the circuit - two conductors on the "A" phase is not a multiwire branch circuit.

So, code compliance aside, is it a good idea? Many electricians do not approve of them, as disconnecting a neutral when one or more of the ungrounded conductors are live results in damage to equipment, and a shock hazard to the person working on the circuit.

The portion of the neutral that is connected to energized loads is carrying current, and can be lethal.

That said, 70% of members polled (here) use multiwire branch circuits (MWBCs), and proudly so. They are more efficient in terms of voltage drop, and in material used. Simply put, using one neutral for three line-to-neutral circuits in a commercial setting saves 66% of conductor over using dedicated grounded conductors for each circuit.

As for the potential for shock hazard, electricians need to be aware of the wiring method and disconnect and lock out all ungrounded conductors supplying a MWBC - just as they would if it were a simple two-wire circuit.

In the 2008 cycle, it appears that all handles supplying MWBCs will have to be tied together to prevent this hazard. Opinions abound about their use, but one thing is for certain; MWBCs continue to be used, and everyone should be aware of their benefits and drawbacks, for the safety of both the electrician and the equipment of the user.

Be sure to check out some applicable sections: 210.4, 501.40, 502.40, 505.21.

Related links:
Inspecting MWBC's in the panel, Aug 2007. Started by Dan Smith, Discusses the new requirements on MWBC's coming up in the 2008, and a discussion about the pros and cons of MWBCs ensued.
 
Last edited:

iwire

Moderator
Staff member
Location
Massachusetts
  • Are anti-shorts (redheads) required for MC cable?

Not for MC.

NEMA has an engineering bulletin that explains that bushings are not required with MC.

Here it is, the original can be found on the web. :)

ENGINEERING DEPARTMENT
BULLETIN
No. 90

August 14, 2002

Use of Anti-Short Bushings for Terminating Type MC Cable
There has been much confusion within the Installation and Inspection communities regarding the
use of anti-short bushings for terminating Type MC cable. The confusion stems from the fact
that some MC cable manufacturers include anti-short bushings with their cable. The inclusion of
anti-short bushings with coils or reels of MC cable is based on historical practice relating to the
requirements of 320.40 of the NEC, which mandates the use of anti-short bushing or its
equivalent protection for Type AC Cable
Fittings used with Type MC Cable are required to be listed per 330.40 of the NEC. NEMA
supports the use of listed fittings for MC Cable. The design of these fittings may or may not
include an insulated throat however, they are required to be provided with a smooth, rounded end
stop so that the metal sheath of the cable will not pass through and the wires will not be damaged
in passing over the end stop. Whether or not an insulated throat is part of the listed product, these
listed MC fittings do not require an additional anti-short bushing. Anti-short bushings that may
be supplied by MC Cable manufacturers are for optional use by the installer, however they are
not required.


ROP #7-116 from the May 2001 Report on Proposals (ROP) for the 2002 NEC was a proposal
seeking to require anti-short bushings on all MC Cable termination installations.
The following is an excerpt from the Panel statement rejecting the proposal:

Anti-short bushings are not required for Type MC cable in accordance with the listing for
the product. The termination fittings approved for use with Type MC cables are designed
such that the wires will not come in contact with the cut edge of the armor; the throat of
the fitting is small enough to prevent contact with the armor. Type MC termination
fittings perform the same function for Type MC cable as Type AC terminations plus the
anti-short bushing do for Type AC cable.



NEMA supports the uniform adoption and enforcement of the NEC and recommends that local
Authorities Having Jurisdiction follow the requirements of NEC Section 330.40, Boxes and
Fittings for MC Cable. Section 330.40 requires that the fitting be listed, but does not mandate the
use of an anti-short bushing.

Distribution List:

Standards and Conformity Assessment Policy Committee
Codes and Standards Committee
NEMA Executive Staff
Edit for formatting
 
Last edited by a moderator:

480sparky

Senior Member
Location
Iowegia
  • How do you insert a picture in the body of your message?
In order to post (insert) photos and images on this forum, the image must have a URL address. Something like htty://www.hereiswheremyphotoisstored.jpg. You must have this URL address in order to insert a photo.

How to post photos:

1. Open an account at Photobucket. It’s free.
Upload your images there.

2. Remember that the larger the image size, the longer it takes to upload and download. Keep that in mind, especially for our users that have dial-up internet service. If need be, please resize your photos before uploading them.

3. When you want to post an image, find the image in your Photobucket list, and there will be four lines underneath it. For this example, I'll use an image I have of a 1953 NEC The second line will be titled “Direct Link”, and will have the URL address for that image. Highlight that line, then Copy (Ctrl-C) the information.




4. Now go to the thread you wish to post a photo in, and begin your response. When you get to where you want to insert an image, click on the yellow icon with the mountain & sun (that is supposed to be a ‘photo’).






5. A small window will appear, asking you for the URL of the image.






Paste (Ctrl-V) the information you copied earlier into the line. The URL address will then appear. Click OK.







6. Now your response will look like this: Do not worry that you can’t see the image. The commands needed by the forums software will take care of that for you.






This is what you'll see:



Note: You are only allowed to post eight images, by the forum software. This includes the smiley faces seen to the right of the reply screen.

mdshunk said:
Before you upload them into your PhotoBucket album, click the 'options' thing I have pointed to here, and pick a size. 640x480 is nice for forums, or you can go smaller. It will automatically resize your stuff to that size when you upload each time.


Edit formatting (intro question)
Edit to add Note at bottom.
Edit to add Marc's note, per Ken's request.
 
Last edited by a moderator:
Status
Not open for further replies.
Top