Articles 225 and 230- Detached Gargae

[david]

not originating from any of our panels which turned out to be powering outside lighting. Does the presence of these circuits trigger labeling requirements in the individual units?

Why? If the disconnects are grouped and labeled that should not be an issue and what does MC have to do with it?:?

maybe I read it wrong,
He stated that the disconnects where not grouped and their was no labeling.

MC cable passes through these individual strip malls without junction or splice points. After you open the service disconnect for this individual unit most guys would proceed to cut out the MC Cable in the unit, since their is no junction point it is difficult to test the cable for voltage, you could open the cable with a splitter then cut each conductor, but that is not how it is usually done.

 

[jtinge]

This discussion parallels one that I've had with my colleagues about buildings that are fed by feeders or outside separately derived systems and not utility fed services. They still want to call any power supply to a building a service, which then triggers use of the wrong code sections.

I made an attempt to compare the code requirements between services and buildings fed by feeders (based on 2014 NEC) to show the commonalities and differences between the requirements. Often there was identical language between the two. I have attached it here for reference. Maybe it will help with the discussion here and if you see any errors let me know.

I also posted a thread in the Proposal forum for a new Figure 225.1 to also illustrate the commonality between the two, but it didn't seem to get any traction.

 

[kwired]

I wonder if you ignore some of art 250 and install 4 ground rods and not connect them together- 2 for the feeder and 2 for the service. Would that not keep from getting a parallel path

How you going to ensure no EGC's from each system never incidentally touch each other - that would allow grounded conductor current from the "other service" to flow anywhere in the EGC network once that happens.

No. Under current code, we are required to run an EGC with the feeder from the house, which gets bonded to the garage GES along with the apartment service. The feeder EGC is effectively bonded to the neutral of both services. Even under older Code where the EGC was not required for a feeder to a separate structure, the neutral (grounded conductor) was still required to be bonded to the structure's GES, so the feeder neutral would end up being the parallel conductor.

NO it is about feeders and services:

225.37 Identification. Where a building or structure has any combination of feeders, branch circuits, or services passing through it or supplying it, a permanent plaque or directory shall be installed at each feeder and branch-circuit disconnect location denoting all other services, feeders, or branch circuits supplying that building or structure or passing through that building or structure and the area served by each.

That is just a condition and requirement if that condition exists. That section itself does not grant permission to supply a structure with a feeder and a service - though it suggests it is possible.

Parallel neutrals and grounding conductors are not necessarily bad.
Separate grounding means without interconnection is considered bad.

You don't want different voltages on the conductive surfaces of different objects in the same building.

Case in point: I worked for a computer company that had a building served by two different power companies (don't ask). There were rooms which had receptacles from both power companies. When you hooked up components of a single computer system using signal cables (using chassis ground as part of the signaling circuit), the cables would sometimes catch fire. The signal cables were unable to pass the current required to equalize the "ground" for both POCOs.

Proper bonding back at the service and feeder disconnecting means should shunt that current away from your equipment.

 

[PetrosA]

maybe I read it wrong,
He stated that the disconnects where not grouped and their was no labeling.

MC cable passes through these individual strip malls without junction or splice points. After you open the service disconnect for this individual unit most guys would proceed to cut out the MC Cable in the unit, since their is no junction point it is difficult to test the cable for voltage, you could open the cable with a splitter then cut each conductor, but that is not how it is usually done.

The meters and disconnects were grouped together outside on the rear of the building. Of course, none were labelled, but that's another story... Luckily, the house circuits were in EMT so once we opened the boxes they were in and realized we couldn't find a breaker for them in either of our two panels we figured out that conduit must belong to someone else. It just seems to me that circuits like that should either have to be run outside the building or the conduits/MCs/JBs for circuits like this should be labelled as originating somewhere else. But maybe I'm just a wus

 

[maallen]

One of my concerns with this is the EGC in the feeder will ultimately be bonded to a service on each end and will carry grounded conductor current from either of those services. This defies some of the reasoning why they no longer allow equipment grounding of separate buildings via the grounded conuctor of the feeder.

Other then that I really don't have an answer as to if a service and a feeder as described are allowed to supply a structure.


I will also say if you have a building supplied by a service as well as another source whether it be a generator, PV, etc don't you have a service and a feeder supplying that building?

You are permitted to have one service, one feeder, and one circuit feeding a separate structure. There are conditions and exceptions to this arrangement. Your GEC and bonding conductors must be sized to the largest conductors feeding the structure.

 

[kwired]

You are permitted to have one service, one feeder, and one circuit feeding a separate structure. There are conditions and exceptions to this arrangement. Your GEC and bonding conductors must be sized to the largest conductors feeding the structure.

Probably correct, does not make the concern I mentioned go away just because it is allowed.

It is still not as clear whether a feeder supplied structure can also be supplied by service(s) as it is clear that a service supplied structure can have multiple services in some instances. NEC allows for separate services for different characteristics such as different voltage, number of phases, frequency, etc. yet they seem to assume with a feeder supplied structure you will have one supply and separately derive those different characteristics if they are needed.

 

[iwire]

It is still not as clear whether a feeder supplied structure can also be supplied by service(s)

Until I see the NEC language that prohibits that, I say it is permitted.

 

[jtinge]

Probably correct, does not make the concern I mentioned go away just because it is allowed.

It is still not as clear whether a feeder supplied structure can also be supplied by service(s) as it is clear that a service supplied structure can have multiple services in some instances. NEC allows for separate services for different characteristics such as different voltage, number of phases, frequency, etc. yet they seem to assume with a feeder supplied structure you will have one supply and separately derive those different characteristics if they are needed.

II. Buildings or Other Structures Supplied by a
Feeder(s) or Branch Circuit(s)

225.30 Number of Supplies. A building or other structure
that is served by a branch circuit or feeder on the load side
of a service disconnecting means shall be supplied by only
one feeder or branch circuit unless permitted in 225.30(A)
through (E). For the purpose of this section, a multiwire
branch circuit shall be considered a single circuit.
Where a branch circuit or feeder originates in these additional
buildings or other structures, only one feeder or
branch circuit shall be permitted to supply power back to
the original building or structure, unless permitted in
225.30(A) through (E).

(A) Special Conditions. Additional feeders or branch circuits
shall be permitted to supply the following:
(1) Fire pumps
(2) Emergency systems
(3) Legally required standby systems
(4) Optional standby systems
(5) Parallel power production systems
(6) Systems designed for connection to multiple sources of
supply for the purpose of enhanced reliability

(B) Special Occupancies. By special permission, additional
feeders or branch circuits shall be permitted for either
of the following:
(1) Multiple-occupancy buildings where there is no space
available for supply equipment accessible to all occupants
(2) A single building or other structure sufficiently large to
make two or more supplies necessary

(C) Capacity Requirements. Additional feeders or branch
circuits shall be permitted where the capacity requirements
are in excess of 2000 amperes at a supply voltage of 1000
volts or less.

(D) Different Characteristics. Additional feeders or
branch circuits shall be permitted for different voltages,
frequencies, or phases or for different uses, such as control
of outside lighting from multiple locations.

(E) Documented Switching Procedures. Additional feeders
or branch circuits shall be permitted to supply installations
under single management where documented safe
switching procedures are established and maintained for
disconnection.

These are requirements for number of supplies to a bldg similar to those found in 230.2 for Number of Services.

 

[GoldDigger]

So we clearly have explicit conditions on more than one feeder or branch and on more than one service. The question for both letter and intent of Code is what about one of each....
Still not satisfactorily answered IMHO. That is, it seems clear that it I'd not flat out prohibited, but what if any are the special conditions.

 

[iwire]

Can I put purple receptacles in a bathroom?


I don't know because I can't find the NEC section that says I can.

 

[jtinge]

So we clearly have explicit conditions on more than one feeder or branch and on more than one service. The question for both letter and intent of Code is what about one of each....
Still not satisfactorily answered IMHO. That is, it seems clear that it I'd not flat out prohibited, but what if any are the special conditions.

Wouldn't we have one of each if we had a service which then supplied a feeder for normal power to an ATS inside a building and a feeder from a customer owned outside generator for emergency power to the ATS? One service and one outside feeder both routed into the building. At least that's the way I'm looking at it. Does it matter if they both don't go to a common ATS?

 

[Dennis Alwon]

Wouldn't we have one of each if we had a service which then supplied a feeder for normal power to an ATS inside a building and a feeder from a customer owned outside generator for emergency power to the ATS? One service and one outside feeder both routed into the building. At least that's the way I'm looking at it. Does it matter if they both don't go to a common ATS?

You don't usually have a service conductor and a generator on at the same time?

 

[iwire]

Cogen supplies like fuel cells, PV and wind provide feeders to buildings with live services.

 

[Smart $]

You don't usually have a service conductor and a generator on at the same time?

But a grid-tied PV system feeder would be on at the same time (and I'm referring to a load-side connected PV system with remote inverter).

 

[jap]

Homeowner metering the apt in the future and charging the tennent is not allowed either.

Why not?

If I was to rent out the attic in my detached garage to someone,whats to keep me from EMON Metering the branch circuits from my Garage Panel to the Upstairs Loads and charging them as I see fit?


JAP>

 

[iwire]

Why not?

If I was to rent out the attic in my detached garage to someone,whats to keep me from EMON Metering the branch circuits from my Garage Panel to the Upstairs Loads and charging them as I see fit?


JAP>

Laws, rules, regulations.

 

[jap]

Laws, rules, regulations.

Was not aware of that.

JAP>

 

[iwire]

Was not aware of that.

JAP>

It is different in each area buy it is common for their to be laws prohibiting the resale of electricity to tenants or if you can do it you have to do it at cost, you can't make a profit on selling it.

But best to check the rules for your area.

 

[jap]

It is different in each area buy it is common for their to be laws prohibiting the resale of electricity to tenants or if you can do it you have to do it at cost, you can't make a profit on selling it.

But best to check the rules for your area.

Dont let my Mother in law know that......

 

[david]

Until I see the NEC language that prohibits that, I say it is permitted.

A building or other structure
shall be supplied by

only

one feeder or branch circuit unless permitted in 225.30(A)
through (E).