60 amp service

[dm9289]

I know generally a 100amp service is the minimum in a dwelling unit.
Is there any exception for a small apt complex.
This apt for example
1. No AC
2. No laundry in apt
3. Natural gas heat
4. Under 500sqft.

 

[tom baker]

No, sorry

 

[augie47]

Does the apartment actually have it's own service or are there multiple apartments off 1 service

 

[dm9289]

Does the apartment actually have it's own service or are there multiple apartments off 1 service

The building has 2 -1200 amp services. Divides into meter sockets in basement

 

[dm9289]

Does the apartment actually have it's own service or are there multiple apartments off 1 service

80 very small apartments

 

[don_resqcapt19]

The apartments are not one-family dwellings covered by 230.79(C). They are covered by 230.79(D) which permits the service disconnect rating to be 60 amps.

 

[dm9289]

The apartments are not one-family dwellings covered by 230.79(C). They are covered by 230.79(D) which permits the service disconnect rating to be 60 amps.

Thanks I’ll do some load calculation on biggest unit. I’m reasonably sure it will be ok.

 

[Earthed]

The apartments are not one-family dwellings covered by 230.79(C)

Don, maybe.
Not enough info in the OP.

 

[don_resqcapt19]

Don, maybe.
Not enough info in the OP.

There is in posts 4 and 5.

 

[Barbqranch]

I used to own, for 33 years, 8 units that had 60 amp disconnects. No AC, no laundry (separate building), natural gas heat, but had microwave and electric stove.
Never had a problem w/ disconnects tripping, even after I replaced the Zinsco ones w/ PB.

 

[Dennis Alwon]

I believe You could put a 60 amp panel at the service and then feed the apt with 30 amps to the apartment

 

[Earthed]

The apartments are not one-family dwellings covered by 230.79(C)

Don,

So, you are saying that a 2-family building only requires 2 - 60-amp panels if the load calculations determined so.

Why does it say dwellings?
(C) One-Family Dwellings. For a one-family dwelling, the service
disconnecting means shall have a rating of not less than
100 amperes, 3-wire.

But I have never seen plans submitted that spec'd only 60-amp panels. So, this has never come up before for me.
Research time.

 

[don_resqcapt19]

Don,

So, you are saying that a 2-family building only requires 2 - 60-amp panels if the load calculations determined so.

Why does it say dwellings?
(C) One-Family Dwellings. For a one-family dwelling, the service
disconnecting means shall have a rating of not less than
100 amperes, 3-wire.

But I have never seen plans submitted that spec'd only 60-amp panels. So, this has never come up before for me.
Research time.

That is a defined term in Article 100 and only applies where the unit in question meets the definition.

Dwelling, One-Family.
A building that consists solely of one dwelling unit. (CMP-1)

So the answer to your question is that the code would only require a 60 amp service disconnect for each of the units in a two-family dwelling unit.

Note that this does not change the load calculations in Article 220, and those calculations may require a larger service disconnect.

 

[Earthed]

That is a defined term in Article 100

Each apartment is most likely a separate building.

Changes from the 2017 NEC.

Building. A structure that stands alone or that is separated
from adjoining structures by fire walls. (CMP-1)

Structure. That which is built or constructed, other than
equipment. (CMP-1)

 

[jaggedben]

Don,

So, you are saying that a 2-family building only requires 2 - 60-amp panels if the load calculations determined so.

Why does it say dwellings?
(C) One-Family Dwellings. For a one-family dwelling, the service
disconnecting means shall have a rating of not less than
100 amperes, 3-wire.

But I have never seen plans submitted that spec'd only 60-amp panels. So, this has never come up before for me.
Research time.

The code is really kind of dumb on this.

If it's given that the load calc for each unit is 60A, then...

If you put in service panel with a 125A main breaker, then you can install two 60A breakers to the meters and panels for the units. The utility probably won't like this setup but it's fine by the NEC.

However if you do something more normal and utility-approved, like install a 2 gang service rated meter bank with breakers for each meter, then your breakers need to be 100A. Yes, your feeders to the units just got bigger too.

In both cases your service conductors can still be rated 120A.

 

[don_resqcapt19]

Each apartment is most likely a separate building.

Changes from the 2017 NEC.

Building. A structure that stands alone or that is separated
from adjoining structures by fire walls. (CMP-1)

Structure. That which is built or constructed, other than
equipment. (CMP-1)

Very unlikely that each apartment is separated from the others by a firewall. The firewall is probably after 6 or 8 apartments. It remains my opinion that none of the apartment is this thread are one-family dwelling units.

 

[don_resqcapt19]

The code is really kind of dumb on this.

If it's given that the load calc for each unit is 60A, then...

If you put in service panel with a 125A main breaker, then you can install two 60A breakers to the meters and panels for the units. The utility probably won't like this setup but it's fine by the NEC.

However if you do something more normal and utility-approved, like install a 2 gang service rated meter bank with breakers for each meter, then your breakers need to be 100A. Yes, your feeders to the units just got bigger too.

In both cases your service conductors can still be rated 120A.

I don't agree. Two units in a single building does not meet the definition of a one-family dwelling. The 100 amp minimum only applies to one-family dwellings.

230.79 Rating of Service Disconnecting Means.
The service disconnecting means shall have a rating not less than the calculated load to be carried, determined in accordance with Part III, IV, or V of Article 220, as applicable. In no case shall the rating be lower than specified in 230.79(A), (B), (C), or (D).
(A) One-Circuit Installations.
For installations to supply only limited loads of a single branch circuit, the service disconnecting means shall have a rating of not less than 15 amperes.
(B) Two-Circuit Installations.
For installations consisting of not more than two 2-wire branch circuits, the service disconnecting means shall have a rating of not less than 30 amperes.
(C) One-Family Dwellings.
For a one-family dwelling, the service disconnecting means shall have a rating of not less than 100 amperes, 3-wire.
(D) All Others.
For all other installations, the service disconnecting means shall have a rating of not less than 60 amperes.

A two-family dwelling would fall under (D) and only require a 60 amp service disconnect, assuming that the load calculation is 60 amps or less.

 

[Little Bill]

I think a lot of people get hung up on the "not less than 100A". The code, as written, doesn't say less than 100A service, it says "not less than100A rated service disconnecting means". So you could have a 100A disconnecting means and feed a building with 60A breaker.

 

[don_resqcapt19]

I think a lot of people get hung up on the "not less than 100A". The code, as written, doesn't say less than 100A service, it says "not less than100A rated service disconnecting means". So you could have a 100A disconnecting means and feed a building with 60A breaker.

I don't see how you can do that with only one piece of equipment. In most cases the breaker itself is the disconnect. Now if you have a fusible disconnect, the disconnect rating maybe different from the circuit rating because fuses smaller than the rating of the disconnect could be installed.

 

[tortuga]

@dm9289 if this 80 apartment building has 80 service disconnects you have other issues.
However I believe your confusing services and feeders.

You state:

The building has 2 -1200 amp services. Divides into meter sockets in basement

80 very small apartments

My guess there must be some kind of service disconnect switch ahead of the 80 meter sockets and 80 apartment feeder breakers and if so that is where article 230 ends.