Maximum number of disconnects - 225.30 and 225.33(A) in 2020 NEC

[tcrews17]

I have a multiplex trailer with 8 "plexes", each or which has its own panel. It's treated as a single building.

The building will be fed by a switchrack, which has a common 1200A bus. There are 8 circuit breakers connected to the bus, each of which feeds one panel on the trailer.

The switchrack has a main breaker. A feed from the utility goes directly to the main breaker. Switchrack is located within 20 feet of the trailer. Switchrack is de-energized by opening the main breaker.

Articles 225.30 and 225.33(A) have come up.

QUESTION: Are we in violation of these articles, or does the service from the utility count as a single supply, and the main breaker serve as a single disconnecting means?

Articles for your reference:

NEC Article 225.33(A) Maximum Number of Disconnects: “The disconnecting means for each supply permitted by 225.30 shall consist of not more than 6 switches or six circuit breakers mounted in a single enclosure... "

225.33(A), it references Article 225.30 Number of Supplies, which states in part “A build 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 unless permitted by 225.30(A) through (E). For the purposes of this section, a multiwire branch circuit shall be considered a single circuit.

 

[LarryFine]

The switchrack has a main breaker. A feed from the utility goes directly to the main breaker. Switchrack is located within 20 feet of the trailer. Switchrack is de-energized by opening the main breaker.

QUESTION: Are we in violation of these articles, or does the service from the utility count as a single supply, and the main breaker serve as a single disconnecting means?

The main breaker is your service disconnect. You're good.

 

[tcrews17]

Thanks for your response!

I had another person disagree and say we were in violation because we exceeded the 6 disconnects...

 

[david]

So your feeding a building consisting of 8 trailers ganged together and treated as a single building. The service and 8 feeders originate on a rack 20 ft away. You have one yes and one no based on the 2020 NEC. witch I do not have therefore can not provide an opinion based on the 2020 code.

under past codes you could not feed the building as described. I am aware that more recent codes have made changes that may address your concern

 

[tcrews17]

Does the main breaker as a single disconnecting means on the switchrack change your opinion?

 

[charlie b]

I had another person disagree and say we were in violation because we exceeded the 6 disconnects...

You don't exceed six disconnects. I agree with Larry. You have one disconnect that has other stuff downstream.

How would this be different from what I have at home (as do millions of other buildings throughout the country), namely a panel with a main breaker and with 42 circuit breakers downstream from the main? Would that "another person" you mentioned say I am in violation because my 42 breakers exceed 6 disconnects?

 

[tcrews17]

You don't exceed six disconnects. I agree with Larry. You have one disconnect that has other stuff downstream.

How would this be different from what I have at home (as do millions of other buildings throughout the country), namely a panel with a main breaker and with 42 circuit breakers downstream from the main? Would that "another person" you mentioned say I am in violation because my 42 breakers exceed 6 disconnects?

That's how I see it as well. Thanks for confirming

 

[jaggedben]

People seem to be missing that you raised article 225 (not 230) and that you implied the switchrack was up to 20ft away from the "trailer" building.

Is the 'switchrack' at the same building? Is there one building or structure, or two? If it's two, then you're in violation, unless you can justify it with one of the permissions in 225.30(A) through (E). Note that if you only had only six feeders then you could perhaps use (B), but you have eight.

 

[Fred B]

People seem to be missing that you raised article 225 (not 230) and that you implied the switchrack was up to 20ft away from the "trailer" building.

Is the 'switchrack' at the same building? Is there one building or structure, or two? If it's two, then you're in violation, unless you can justify it with one of the permissions in 225.30(A) through (E). Note that if you only had only six feeders then you could perhaps use (B), but you have eight.

Nice catch. The switch rack is (based on OP statement) a separate structure, providing feeder to another structure. From that it would appear 225 does come into play. Then the Max of 6 disconnects of 225 also become valid issue for consideration. Could though the AHJ give consideration for this section as an exception?:
225.30(C) 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

If not another option but would not really be liked by most (big cost increase) would be to provide 4 larger feeders to the separate structure then split it there with 2 disconnects for each of the feeders (grouping) thus not more than six at any structure.

 

[tcrews17]

Nice catch. The switch rack is (based on OP statement) a separate structure, providing feeder to another structure. From that it would appear 225 does come into play. Then the Max of 6 disconnects of 225 also become valid issue for consideration. Could though the AHJ give consideration for this section as an exception?:
225.30(C) 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

If not another option but would not really be liked by most (big cost increase) would be to provide 4 larger feeders to the separate structure then split it there with 2 disconnects for each of the feeders (grouping) thus not more than six at any

People seem to be missing that you raised article 225 (not 230) and that you implied the switchrack was up to 20ft away from the "trailer" building.

Is the 'switchrack' at the same building? Is there one building or structure, or two? If it's two, then you're in violation, unless you can justify it with one of the permissions in 225.30(A) through (E). Note that if you only had only six feeders then you could perhaps use (B), but you have eight.

These are good points. Yes it's a separate structure 20ft or less from the building, and there is only one building since these modular trailers are made it connect seamlessly. These are modular units each with their own panel. If it was a traditional building, I'd hang a distribution panel on the outside and feed each subpanel from it.

We were planning to put this switchrack as close as possible to the building, and we equipped it with a main breaker so all power could be disconnected by opening a single breaker.

I believe the intent of this article is to limit thr number of disconnecting means that would have to be operated to completely remove power from a building. Without the main breaker, I'd say it's a violation because 8 switches would have to be opened, but with the main, it's only one.

Thoughts?

 

[wwhitney]

Thoughts?

If the rack is 1' from the building, then Article 225 doesn't apply, and your arrangement is fine.

If the rack is 100' from the building, then Article 225 applies and you need to run a single feeder to a single main disconnect on/at the building (check the exact wording).

Where the dividing line is between the above two cases is a judgement call. How close can you get the rack to the building?

Cheers, Wayne

 

[jaggedben]

... and there is only one building since these modular trailers are made it connect seamlessly. These are modular units each with their own panel. If it was a traditional building, I'd hang a distribution panel on the outside and feed each subpanel from it.
...

In your original post, you gave it as a given that the multiplex trailer was a single building. But if that's just your subjective supposition, and not already determined by the AhJ, then maybe you should consult the NEC definition of a building. It allows for multiple units that are separated by firewalls to be treated as multiple buildings. It doesn't hinge on whether the connections between units are 'seamless' or anything like that.

 

[tcrews17]

In your original post, you gave it as a given that the multiplex trailer was a single building. But if that's just your subjective supposition, and not already determined by the AhJ, then maybe you should consult the NEC definition of a building. It allows for multiple units that are separated by firewalls to be treated as multiple buildings. It doesn't hinge on whether the connections between units are 'seamless' or anything like that.

No firewalls between them. We've established it's considered a single building.

 

[tcrews17]

If the rack is 1' from the building, then Article 225 doesn't apply, and your arrangement is fine.

If the rack is 100' from the building, then Article 225 applies and you need to run a single feeder to a single main disconnect on/at the building (check the exact wording).

Where the dividing line is between the above two cases is a judgement call. How close can you get the rack to the building?

Cheers, Wayne

I originally said 20', but we could probably squeeze it a little closer. Probably can't get less than 10' because of the switchrack foundation and the metal framed hitch on the end of each trailer.

 

[david]

Here our building department would look at these as manufactured buildings and you may get a temp occupancy permit, under specific circumstances. Some on this forum would look to different articles in the NEC.

Here you would be referred to article 550 manufactured homes not being used as a dwelling.

Article 550 would only allows one feeder when the service equipment is mounted on a pedestal / rack within 30 feet of the trailer. If a trailer has by manufactured instructions a permanent foundation than the service equipment could be mounted on the trailer

 

[david]

If the rack is 1' from the building, then Article 225 doesn't apply, and your arrangement is fine.


Cheers, Wayne

do you have a reference where the distance makes a difference.

 

[Fred B]

Here you would be referred to article 550 manufactured homes not being used as a dwelling.

Actually a better fit would be article 545. This section might help.
545.22(B) Number of Supplies.
Where two or more relocatable structures are structurally connected to form a single unit and there is a factory-installed panelboard in each relocatable structure, each panelboard shall be permitted to be supplied by a separate feeder.

 

[jap]

You may be allowed to supply each panelboard with a separate feeder, but, seeing as how this is now considered (1) Structure, I still don't think you'd be allowed to have more than 6 movements of the hand to disconnect the structure from the service.

JAP>

 

[david]

Actually a better fit would be article 545. This section might help.
545.22(B) Number of Supplies.
Where two or more relocatable structures are structurally connected to form a single unit and there is a factory-installed panelboard in each relocatable structure, each panelboard shall be permitted to be supplied by a separate feeder.

ok perhaps I'll be able to get a look at the 2020 NEC. Does this article require the trailers to be supplied by a feeder / Feeders or can the service equipment be mounted on or in the trailer?

thank you

 

[tcrews17]

Actually a better fit would be article 545. This section might help.
545.22(B) Number of Supplies.
Where two or more relocatable structures are structurally connected to form a single unit and there is a factory-installed panelboard in each relocatable structure, each panelboard shall be permitted to be supplied by a separate feeder.

Apparently that's the article I'm looking for. And combined with the fact that there's a main breaker to disconnect all at once, we're good. Thank you!