IRC vrs NEC

[Fritz]

An electrical inspector is saying you cannot have separate services to individual townhomes, unless you have the NEC recognized 2 hour fire wall. He does not want to recognize the 2 one hour property line walls. Because it looks like one building. Has anyone did the cross reference discussion between the 2 codes and come up with a rational that a NEC electrical inspector agrees with.

Fritz

 

[Francis Vineyard]

Didn't know that was in the NEC other than the information given in Annex E, Type of Construction; Type V construction has two categories: One-Hour Rated and Non-Rated.

 

[fatboy]

Don't have any code books at home, but don't think that the NEC speaks as to how to separate "buildings" for separate services. We have strip malls all the time that have separate services with only one-hour separations between tenants, as do most AHJ's. Ask him how he deals with those?

 

[globe trekker]

Fritz,

Politely and civilly ask the inspector to please provide the NEC reference,

so that you can understand the requirement fully. See what he supplies

and go from there!

Also, see Article 230 in the 2008 NEC for guidance.

.

 

[brudgers]

An electrical inspector is saying you cannot have separate services to individual townhomes, unless you have the NEC recognized 2 hour fire wall. He does not want to recognize the 2 one hour property line walls. Because it looks like one building. Has anyone did the cross reference discussion between the 2 codes and come up with a rational that a NEC electrical inspector agrees with.Fritz

There is nothing in any of the construction codes about "townhomes."

A master disconnect for a group of townhouses is a really good idea in general, and I've seen jurisdictions require it based on the specific requirement for a firewall.

 

[texasbo]

230.2 allows only one service per building, with some exceptions. A properly constructed townhouse, with a one hour exterior wall adjacent to a property line, is a single structure, and would be clearly allowed by the NEC to have it's own service. I don't care what it "looks" like.

So if this inspector is requiring only a single service for all of the townhomes, how will the service equipment be accessible to all occupants?

Fatboy - do your strip centers actually have multiple services (an individual drop to each space), or a single service with a gutter and multiple meters?

 

[fatboy]

TXBO......good point........temporary mind fart......not out in the field enough anymore.......need to get back out.

We do have separate drops to duplexes and townhouses constructed under the IRC.

 

[brudgers]

230.2 allows only one service per building, with some exceptions. A properly constructed townhouse, with a one hour exterior wall adjacent to a property line, is a single structure, and would be clearly allowed by the NEC to have it's own service. I don't care what it "looks" like. So if this inspector is requiring only a single service for all of the townhomes, how will the service equipment be accessible to all occupants?

Fatboy - do your strip centers actually have multiple services (an individual drop to each space), or a single service with a gutter and multiple meters?

If they're "townhomes" then they are not separate buildings under any recognized construction code.

If they are townhouses, the interpretation of 230-1 is ambiguous.

"Other structure" may be taken as the group of attached townhouse buildings. and therefore limited to a single service. This interpretation is implied elsewhere in IRC [see R322].

 

[texasbo]

"Other structure" may be taken as the group of attached townhouse buildings. and therefore limited to a single service. This interpretation is implied elsewhere in IRC [see R322].

You said "buildings".

So, are you saying that two structures built on each side of a property line, each with one hour walls adjacent to the property line is a single building?

I think you said it right the first time; Buildings .

I don't understand your reference to R322 (accessibility?). R317.2 clearly says that each townhouse shall be considered a separate building. NEC 230.2 clearly says that each building shall have a single service with exceptions. Ignoring IRC completely, where does the NEC say that a single structure, built on it's own lot, with one hour walls adjacent to the property line, regardless of what's on the other side of the PL is not a single building? Using that logic, every single family subdivision would be allowed only one service.

 

[brudgers]

As I said the interpretation of "building or other structure" can be read two ways.

In one, the designer gets the choice. They may provide one service to each building or one to the entire structure (of several townhouses).

The other way of reading it is, you may have one only service to a structure regardless of the number of buildings it contains (and this is consistent with IRC 322).

The second is obviously the most restrictive reading...and also the safest installation.

I've been on both sides of the counter on the more restrictive interpretation.

In all honesty, grouping the services usually provides a cleaner installation since the house panel has to go somewhere in most townhouse developments anyway.

BTW, building townhouses with two separate one hour walls is a PITA since both walls need to be rated for fire exposure from both sides.

 

[texasbo]

Are you in 2009 IRC? I'm not getting how R322 has anything to do with this. Agree with designers choice, and agree that single service might be cleaner, although it would be difficult to provide each owner access to service entrance equipment, a requirement in NEC.

However, I can find no code justification for an inspection dept allowing only one service to multiple buildings, on multiple properties, which the OP said this is. If single property, then I would completely agree, unless there was a 2 hr wall.

PITA? How about virtually impossible to do it correctly.

 

[brudgers]

The service on a block of townhouses is often on one of the end units along with the main disconnect. The owner can disconnect their service at the panel in their dwelling.

See my signature regarding code versions.

The interpretation is that there is only one structure.

 

[texasbo]

Yes, I saw your signature; that's why I couldn't understand your reference to 322, which is regarding accessibility when there are 4 or more sleeping units or dwelling units in a single structure, especially when 317 specifically states that each townhouse shall be considered a separate building.

Another consideration is NEC 230.3, which actually prohibits one building or structure from being served through another. Therefore, if only a single service is provided for this group of townhouses, the branch or feeder to each (note that they are not services by definition) must be outside of the buildings. And each occupant must have access to the service entrance equipment, not just their panel/overcurrent devices. You can certainly do it that way, if the designer chooses, but the owner of the building that has the service drop would have to make his property available to all other occupants. You don't usually have that concern with apartments or condos where there is a common maintenance entity.

 

[brudgers]

R322 is used to require a structure containing multiple townhouse buildings to provide the accessibility required by the Federal Fair Housing Act.

The only time you could have four dwelling units in a structure under IRC is if each dwelling unit is also a townhouse/building.

Per the IRC you don't get a new structure at the property line of each townhouse.

That's why it is relevant to the restrictive way of interpreting NEC 230.1

IRC supports the interpretation.

 

[texasbo]

R317 of the IRC says that each townhouse shall be considered a separate building.

Section 230 of the NEC allows each building to have at least one service.

Section E3501.2 of the IRC says one and two family dwelling units shall be supplied with only one service; it does not have the same restriction for townhouses.

The IRC and NEC support each townhouse having its own service, if the designer so chooses.

There is nothing in either code that supports a building department denial of each townhouse having its own service.

 

[brudgers]

Some jurisdictions do not believe that it is the designer's choice to provide multiple services to a single structure.

I'm not saying it is my preference, but I believe it is a plausible position and supported by the codes.

And it is definitely safer.

 

[bldginsp]

Texasbo, I agree with you 100% on this as our city is littered with TH's and we view them as separate buildings also. Our BO used to help write the NEC and agrees with this approach also. We have had it the other way also with one service on the end of the row of TH's, grouped meter banks and service disconnects, conductors ran under the slab to each unit (considered outside the building by NEC) and overcurrent current devises installed in each TH. Both ways are legal per code.

 

[Paul Sweet]

If the townhouses are on separate lots, as the OP implies, and a single service is installed for a group of townhouses, then easements have to be provided for access to the grouped service and the feeders that run across other lots. This can get messy fast.

 

[Fritz]

I understand the varied opinions. Our opinion here is that when built as a townhouse, each unit will have all its own separate services. Essentially like any other single family dwelling, just that it has two walls with zero side yards. Which must meet that particular code requirment? Just because you have a number of them right adjacent to each other should not cause a change in how any code should look at it. We have been able to get the electrical inspector to see the issue, and understand how a property line wall, vrs a 2 hr fire wall can be different and at the same time may be considered a common property line wall. We just all needed to get to the same dictionary first.

When sailing with a friend of mine, who had different color lines for everything, I asked why the different color lines? He said you may know what a jib line is, or an outhaul line. But to others, grab the darn blue rope. KISS Fritz

 

[peach]

How would you justify having the service cable passing between property lines? Each dwelling is in fact a separate building. IF it's one meter center, it could require a main disconnect (6 throws of the hand).. 5 units and a house meter or 6 units.. but then the fire department will end up disconnecting power to all units in an emergency.

 

[Uncle Bob]

If adopted properly; there is no IRC vs NEC. The IRC has the Electrical requirements right out of the NEC and a cross referenced in appendix L. Unfortunate many AHJs; don't adopt the right year NEC to coincide with that year IRC.

There also other electrical requirements in the IRC that are "in addition to" the NEC requirements; example - R303.6 Stairway illumination.

Got up too early. That's my excuse, and I'm sticking to it.

Uncle Bob

 

[peach]

You're right, UB.. there is no conflict between IRC-E and NEC, since the NFPA essentially writes the IRC-E provisions (which is why you'll never see electrical code issues on the ICC agenda). however, when you are talking about property line things, the NEC is mute... so we need to dig a little deeper (maybe IBC sometimes).. trust me.. try to get thru the electrical plan reviewer exam... you need to know the IBC cold.