230.40 Ex. 3 and grounding and bonding

[wdingman]

The way I read that section of the Chicago code section 560.23 (B) only applies if your supplying a one or two family dwelling with a 'service', in your case if you wanted to use two 200A breakers you'd be supplying the dwelling with a '4 wire feeder' and your service would be to a 'accessory structure'. Your not required to supply a one family dwelling with only a service that would be silly.

I like that idea, but the city doesn't buy the argument.

Why not?

Well anyway, every single service that has a meter and a service disconnect with a metal raceway between them will have neutral current flowing on that metal raceway.

For all practical purposes, Chicago requires the use of IMC or RMC for service entrance raceways. MI is also permitted, but who would use that?

 

[wdingman]

Here is what I would doView attachment 2580768

I would do this, too; in fact, I think it's absolutely the best solution. But the AHJ calls it a violation because their amendments state that the service disconnect for a single-family home must be inside the house.

 

[wdingman]

Current code allows this nominally. (It's 250.64(D)(3).) The problem is it requires the GEC termination to be accessible and I understand many AHJs don't consider the meter socket or trough accessible once the utility seals it. (Also some utilities may prohibit it, while I hear others require a rod to the meter. ).

Maybe propose a clarification that a utility seal shall not be considered to make an enclosure inaccessible for the purposes of that requirement.

I definitely agree the 2nd diagram is better, although I'd like to see the options preserved.

I don't think this would work in my scenario. 250.64(D)(3) is for a "Building or Structure with Multiple Disconnecting Means in Separate Enclosures." My situation is two buildings; each is fed with one set of SE conductors.

Also, in your set up, wouldn't you still have to bond the neutral conductor to the service entrance enclosure? And wouldn't that still create a parallel path for fault current?

 

[ActionDave]

I like that idea, but the city doesn't buy the argument.

For all practical purposes, Chicago requires the use of IMC or RMC for service entrance raceways. MI is also permitted, but who would use that?

Your inspector has cornered himself. You can't have a legal, properly wired service without objectionable current. Maybe he's just waking up to this.

 

[jaggedben]

I like that idea, but the city doesn't buy the argument.
...

That's insanity. Is this just one inspector saying this or do all his colleagues agree?

 

[tortuga]

Read the actual the Chicago code, to me it does not prohibit a feeder from supplying a SFD. Do your read that in there?
There a re extra rules in 560 if you have a service to a SFD.
You have a service to a garage which in code language is a 'residential accessory structure'.
From the garage to the single family dwelling (SFD) you have a outdoor feeder that falls under article 225.
Since you don't have a service supplying the SFD the code extra rules in 560 don't apply, simply the normal rules under 225.
If I am uncertain about a AHJ's take on a complex code rule what I do is submit a plan with my permit applications and request a 'plan review' instead of a 'over the counter' permit
Then if they reject my plan at least its not installed yet.
Hope that helps.

 

[electrofelon]

I like that idea, but the city doesn't buy the argument.

For all practical purposes, Chicago requires the use of IMC or RMC for service entrance raceways. MI is also permitted, but who would use that?

Why does it show PVC on the one side?

 

[tortuga]

Why does it show PVC on the one side?

Here is the Chicago code section:

2. Revise section 230.43 to read:

"Wiring Methods for 1,000 Volts, Nominal, or Less. Service-entrance conductors shall be installed in accordance with the applicable requirements of this Code covering the type of wiring method used and shall be limited to the following methods:

(1) Rigid metal conduit

(2) Intermediate metal conduit

(3) Service-entrance cables for existing residential occupancies of not more than three dwelling units

(4) Busways

(5) Cablebus

(6) Mineral-insulated, metal-sheathed cable."

 

[electrofelon]

Here is the Chicago code section:

That doesnt seem to answer my question

 

[wdingman]

Why does it show PVC on the one side?

I'd have to ask for special permission for that part. The idea is stopping neutral current over the raceways. Doing anything with the service entrance raceway from the house to the garage would be a major pain, but the panel in the garage is back-to-back with the meter.

 

[wdingman]

That's insanity. Is this just one inspector saying this or do all his colleagues agree?

The field inspector gave up. His supervisor never even came out. I have multiple emails in to the city, but no response yet.

 

[wdingman]

Read the actual the Chicago code, to me it does not prohibit a feeder from supplying a SFD. Do your read that in there?
There a re extra rules in 560 if you have a service to a SFD.
You have a service to a garage which in code language is a 'residential accessory structure'.
From the garage to the single family dwelling (SFD) you have a outdoor feeder that falls under article 225.
Since you don't have a service supplying the SFD the code extra rules in 560 don't apply, simply the normal rules under 225.
If I am uncertain about a AHJ's take on a complex code rule what I do is submit a plan with my permit applications and request a 'plan review' instead of a 'over the counter' permit
Then if they reject my plan at least its not installed yet.
Hope that helps.

I have read it carefully many times.

See 230.70: "Means shall be provided to disconnect all conductors in a building or other structure from the service-entrance conductors."

See 230.70(A)(1): "(1) One-Family Dwellings. In one-family dwellings the service disconnecting means shall be installed at a readily accessible location in the basement or first floor of the building at a point not exceeding 1.52 m (5 ft) from the point of entry into the building."

The inspector's take is that there is a service supplying a single-family dwelling; therefore, the service entrance conductors must terminate in service equipment inside the house.

I did submit drawings to the city before the permit was issued. They told me that they issued it without reviewing them.

 

[LarryFine]

The meter and service enclosures and raceways are considered part of the neutral itself.

 

[tortuga]

The inspector's take is that there is a service supplying a single-family dwelling;

I stop him or her right there and review some article 100 definitions
a one family dwelling is;

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

Dwelling Unit. A single unit, providing complete and inde-
pendent living facilities for one or more persons, including per-
manent provisions for living, sleeping, cooking, and sanitation.
(CMP-2)

Note: there is no garage, or accessory structures included in a dwelling unit.

A feeder is defined as;

feeder;

Feeder. All circuit conductors between the service equipment,
the source of a separately derived system, or other power supply
source and the final branch-circuit overcurrent device. (CMP-2)

There is no Chicago amendment prohibiting a feeder from supplying a dwelling unit.
The amendment applies to a service on a dwelling.
Happy thanksgiving.

 

[ActionDave]

The meter and service enclosures and raceways are considered part of the neutral itself.

Electrically and under a code compliant install they are. I don't think there is any wording in the NEC that states this, it's just understood.