NEC 230.72

[automaticrain]

I have received an inspection report that reads:
NEC 230.72 - 6 main throws max. allowed to shut off
service. What does this mean exactly? I asked the
inspector, but they were somewhat vague.

 

[iwire]

Re: NEC 230.72

It sounds like you have a service that can not be entirely shut of with six or less switches.

 

[automaticrain]

Re: NEC 230.72

Does this mean then that there should only be 6 or less breakers in the panel? I have always seen more
breakers in a panel elsewhere. In what way can this violation be correted?

[ November 22, 2003, 12:16 PM: Message edited by: automaticrain ]

 

[iwire]

Re: NEC 230.72

Can you describe what it is you have?

You could have many more than six breakers, but there would be one main breaker or switch ahead of them to shut down the panel.

You are limited (with a few exceptions) to six "service disconnects"

You may have as many branch circuit breakers of fuses that you need.

The most common way this is handled is a panel with a main breaker which would be the "service disconnect" the panel itself might have up to 42 breakers.

Now what can happen over time as there are no spare circuits people keep adding additional small panels once you reach a point where it takes more than "six throws of the hand" to shut off all the buildings power you have a violation.

Not knowing what you are dealing with it is tough to say what the easiest way to correct this is.

Adding a fusible disconnect rated to the service size ahead of the other equipment may be the fastest way out.

But you will have to do your grounding and bonding in this switch.

 

[automaticrain]

Re: NEC 230.72

I have added an addition to our home with a sub panel. We have the main panel in the house with a main shut off breaker. Also, there is a sub panel in the shop in the back yard. Each sub panel has a 100 amp breaker and the main has A 60 amp breaker. It seems to me there are only 3 throws to make sure the power would be off in all three areas. Would do you think?

 

[roger]

Re: NEC 230.72

What you describe is per the code.

The main breaker would cut off everything downstream, this is one throw of a switch.

At either of the two subpanels the 100 amp (sub mains for lack of better term) breakers would shut these down at their locations.

The subpanel located inside the house wouldn't need this 100 amp breaker at all.

I take it this is a Home Inspectors report?

The explanation was vague because the inspector doesn't understand the installation.

Roger

[ November 22, 2003, 02:37 PM: Message edited by: roger ]

 

[steve66]

Re: NEC 230.72

One thing iwire didn't mention that may affect your installation: all 6 switches should be at the same location. From your posts, I'm not sure if your installation meets this requirement.

One reason for this requirement is if there is a fire, the fire department will need to shut off power to your house before flooding it with water. If all the switches aren't at the same location, the fire department won't know that they don't have all the power shut off, and that can be a real danger to them.

Steve

 

[wildman]

Re: NEC 230.72

steve...since 230.72 deals with disconnect grouping.... would the violation be resolved by replacing the 100 amp subpanel in the house with a "no-main" 100 amp panel? I believe a new panel comes with stick-ons if you use it as a service disconnect. houses built in the last few years are required to have service disconnects installed on the exterior near the meter base for firemen to shut off power. since the shop is located away from the house...would 230.72 apply? wildman

 

[roger]

Re: NEC 230.72

Steve and Wildman, look at Automaticrain's third post.

We have the main panel in the house with a main shut off breaker.

This covers both panels inside of the house.

Each sub panel has a 100 amp breaker and the main has A 60 amp breaker

This seems to say the panel in the out building has its own main satisfying 225.31

Roger

 

[hbiss]

Re: NEC 230.72

If this was a "home inspection report" I would take it with a grain of salt. Unfortunately many of these home inspectors are not well versed in electrical matters. From what you describe your service is fine.

 

[wildman]

Re: NEC 230.72

conclusion...."inspector doesn't understand the installation" I guess I don't either! bottom line, call the AHJ and get a clarification before making any costly repairs!

 

[hurk27]

Re: NEC 230.72

The 6 disconect rule applys to each building seperately the out bulding does not count into the house 6 disconect's what he has is only two means of disconects not how many breakers there is in the panel. But as he stated that the sub-panel "has it's own main" If this sub panel is being fed from the service entrance wires before the first main breaker and is located away from the main panel in the house I think there is some violations here as one I doubt that it's fed with 4 conductors. and the grouping of the mains would be 2 the fact that the main service is only 60 amps leaves me to belive the service conductors could be undersized. and how are these sub-panels bonded and or grounded (GEC)? You might want to get a electrican to look at it just incase.

 

[steve66]

Re: NEC 230.72

Wildman: I don't think the main breaker in the 100A panel needs to be eliminated, however I do agree a single disconnect outside at the meter that shuts off power to everything would have been the best way to do this. I don't know of any requirement that the disconnect be outside by the meter but I definitely like the idea. (The local power company in your area may be requiring this.)

Roger: I'm still not sure he hasn't tapped off ahead of the main for another subpanel in the house (although I'll admit that's unlikely, I thought I would throw out "grouping" rule anyway).

You say that each building has it's own disconnect. I'm not sure that is sufficient. There is only one service. The other buildings are fed with feeders from the house. I believe the disconnects at the house have to shut off power to all the buildings. See 230.3 (services) - One building or structure not to be supplied through another.

Steve

 

[roger]

Re: NEC 230.72

Steve, the "service" is already covered by the "Main Breaker" in this case.

Here is the problem in this thread, article 230 stops at the aforementioned "Main Breaker"

The out building is served by a "Feeder" not a "Service" and therefor would be under 225.30, 225.31, 225,32, and 225.33.

Roger

[ November 25, 2003, 09:59 AM: Message edited by: roger ]

 

[wildman]

Re: NEC 230.72

automaticrain....haven't heard from you in a while....hope these posts helped you understand a little better...........steve,,appreciate your response...........roger,,I understand a little better myself....thanks!