225.30 and prefab classrooms

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dnem

Senior Member
Location
Ohio
Many schools in my area are not building additions when they need to expand. There is a proliferation of prefab classrooms. These are free standing doublewide mobile home trailer type prefabs that are placed on a side lawn next to the school and then tend to multiple as the years go by.

The school job that I inspected today had a 600amp exterior pedestal disconnect feed from the "regular" school building. At some point in the past, before my time as inspector here, 2 doublewide prefabs were plopped down on the lawn nearby and feed underground from that 600amp pedestal. My inspection today was the trench to a newly arrived third prefab and the EL contractor was installing it the same way as the other 2.

The doublewides come as 2 seperate trailers that are connected together and each half has a 100amp panel for all of the wiring in that half. When installation is complete, there is no wall between the 2 halves. There is also no electrical connections between the halves.

The trench that I looked at duplicated the other previous trailer feeds and had 2 conduits from the 600amp pedestal laying next to each other and running down the trench to the trailer but then separating at the trailer and entering the 2 panels separately. This struck me as a violation of 225.30. I don't see that any of the "unless" items in (A) thru (E) apply, but I'm not confident that I'm making the right call.

Exactly what kind of installation is covered by the last sentence in 230.2 [the sentence that starts by saying, "For the purpose of 230.40, Exception No. 2 only"] ?

Would this installation be compliant if it was a service under 230.2 / 230.40 but is not compliant for a feeder under 225.30 ?

What do you think ?

David
 

benaround

Senior Member
Location
Arizona
David,

I think this would be a "special permission" application (JMO) with the proper

signage at all locations.

Also, I thought manafacture's instructions, located on a metal panel inside

somewhere, spelled some of this info out.
 

dnem

Senior Member
Location
Ohio
thinfool said:
You might have a look at 550.19 (B)

They are permanently installed feeders buried underground thru the lawn.

Thanks for your answer. It might apply in another installation that I have to deal with in the future, but not this one.

David
 

dnem

Senior Member
Location
Ohio
benaround said:
David,

I think this would be a "special permission" application (JMO) with the proper

signage at all locations.

Also, I thought manafacture's instructions, located on a metal panel inside

somewhere, spelled some of this info out.

230.71(C)(1) ?

I think you're right that this would be the only item in (A) thru (D) that would apply. What would the special permission be based on ? Projection of the possible hazards of allowing this installation ?

David
 

Smart $

Esteemed Member
Location
Ohio
David,

This may be a matter determined by other authority. I'm certain mobile facilities as such are "titled" tangible property, same as mobile "homes", where the title is based heavily on the framework which transports the construction thereupon. The double wide you refer may have been sold under two titles, one for each side. As long as the framework is not altered to be outside the scope of the titles, they remain individually titled entities and cannot be considered one structure. Otherwise, your arguments stand.
 

benaround

Senior Member
Location
Arizona
David,

The disconnecting means for the feeders is not required to be mounted on

the building (225.32). The 600a disconnect meets the requirement,also if

six or less disconnects grouped at this location.

If you had no problem with a 200a disc. on this building feeding the 2-100a

panels,then you should have no problem with the situation at hand.

FYI, most of this info comes from the 2005 Handbook in the explanatory

sections,for what it is worth, school campus locations were mentioned.
 

jtester

Senior Member
Location
Las Cruces N.M.
David

I tend to agree with you that there ought to be a legal disconnect. I don't see how, in general, running 2 separate 100 amp feeders will comply with 225.30, unless the breakers that they originate from are relatively close to the building. In New Mexico we are allowed 30' from the building to the disconnect for the first time this year.

As far as the "tangible property" idea, I know of no allowance in any code that classifies a structure as multiple buildings based solely on multiple ownership.

I do many of these designs this time of year, and always call for a single disconnecting means.

Jim T
 

Smart $

Esteemed Member
Location
Ohio
jtester said:
...

As far as the "tangible property" idea, I know of no allowance in any code that classifies a structure as multiple buildings based solely on multiple ownership.

...
It's not a matter of code allowance. Forget the tangible part. These are titled mobile units. Titled in quite the same manner as your automobile. I've seen as many as 6 units pulled onto a site and connected via construction. The construction does not relieve the fact that each unit is individually titled and still mobile worthy (after removing said joining construction, of course). In many situations these units are considered to be temporary facilities. I'm not saying they cannot be considered one structure if so desired, but I am saying this is ownership disccretion, where the owner has the right to say each or an individual unit shall have it's own power service.

Here's an analogy of what you are saying: A person owns several vehicles?cars, trucks, etc.?but because he is but a single individual and can only drive one vehicle at a time, he can only have gasoline in the vehicle he is driving. The only time he can have gasoline in all vehicles is when all are parked adjacent to one another. Perhaps a bit of a stretch, but an analogy nonetheless :D
 

dnem

Senior Member
Location
Ohio
Benaround,

I'm reading 225.32 and getting the exact opposite conclusion than you apparently are.

I'm reading the Handbook Commentary and it confirms my conclusion that multiple feeders dettached from the building are not allowed. The only thing that the Handbook says can be "remote" from the building is the service disconnecting means. It clearly states that the "feeder or branch-circuit disconnecting means is to be located inside or outside the building or structure supplied, at the point nearest to where the supply conductors enter the building or structure".

David
 

dnem

Senior Member
Location
Ohio
Smart $ said:
David,

This may be a matter determined by other authority. I'm certain mobile facilities as such are "titled" tangible property, same as mobile "homes", where the title is based heavily on the framework which transports the construction thereupon. The double wide you refer may have been sold under two titles, one for each side. As long as the framework is not altered to be outside the scope of the titles, they remain individually titled entities and cannot be considered one structure. Otherwise, your arguments stand.

"they remain individually titled entities and cannot be considered one structure"

Installations must follow 3 things:
1] NEC (and any local codes if any)
2] Approved Prints
3] Manufactures Instructions

Meeting one of those requirements, such as manufacturers instructions does not relieve the obligation to meet the other requirements. No matter how the trailer is titled or considered by the manufacturer, NEC must be satisfied.

Also, in Ohio, state building code defines what requirements must be met to be considered separate structures. One of those requirements for 2 structures attached together is the presence of a fire wall. These trailers have no fire wall between the halves, they actually have no wall at all.

Whether or not the manufacturer considers them separate structures or not does not affect Ohio law.

David
 

Smart $

Esteemed Member
Location
Ohio
I'll concede the point on the firewall issue, as I have no argument with that. Nonetheless, I feel compelled to point out it is also Ohio law that requires the units to be titled. You cannot simply limit the "law" to what you consider to be the issue at hand.
 

Smart $

Esteemed Member
Location
Ohio
dnem said:
Benaround,

I'm reading 225.32 and getting the exact opposite conclusion than you apparently are.

I'm reading the Handbook Commentary and it confirms my conclusion that multiple feeders dettached from the building are not allowed. The only thing that the Handbook says can be "remote" from the building is the service disconnecting means. It clearly states that the "feeder or branch-circuit disconnecting means is to be located inside or outside the building or structure supplied, at the point nearest to where the supply conductors enter the building or structure".

David
This is clearly an Article 550, III. Services and Feeders, 550.32(A)
issue for service to the structure. Thereafter, it falls back to Article 230 first, then Article 225 if at all. JMO

You stated in your original post there is a 600A pedestal but made no mention of the internal arrangement for loads. Are you saying there is only a 600A main and all [service] feeders are connected to it? Additionally, how is the pedestal fed... i.e. to what is the feeder for the pedestal connected at the other end? You said "regular" school building but that is really quite vague. Answers may not make a difference. I'm just feeling a little short on the "picture" :D
 

benaround

Senior Member
Location
Arizona
David,

I got that info from NECH 2005, page 127, the very last paragraph (in the green)

It's talking about free-standing equipment, such as the 600a at this job?

This being a school may also fall under 225.32 ex.#1, do the schools in your

area follow 'safe switching proceedures' and hire 'qualified individuals' .
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
dnem said:
This struck me as a violation of 225.30.
Moron! Putz! Idiot!

Sorry, wrong thread. :D

I agree, I believe this structure requires a disconnect to be installed per 225.30. One panel feeding the two seperate panels would fit the bill. :cool:

How did the others pass, I wonder? :confused:
 

dnem

Senior Member
Location
Ohio
georgestolz said:
I agree, I believe this structure requires a disconnect to be installed per 225.30. One panel feeding the two seperate panels would fit the bill. :cool:

How did the others pass, I wonder? :confused:

As you'll see below, agreeing with me was the wrong thing to do.

Smart $ said:
This is clearly an Article 550, III. Services and Feeders, 550.32(A)
issue for service to the structure. Thereafter, it falls back to Article 230 first, then Article 225 if at all. JMO

I brought this subject to the floor during the Akron IAEI meeting Tuesday night. The monthly meeting is always conducted by the code making panel members of the Akron IAEI, Oran Post panel#6, Tom Moore panel #11, and Tim McClintock newly appointed to panel #12. All 3 agreed that 550 applied and 225 didn't apply.

For trailers 225 only applies to items not covered by 550.
550.32 & 33 covers services and feeders and nowhere restricts the number to one single supply.

Smart was right.
I was wrong
and George "bet on the wrong horse".

David
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
All 3 (wise men ;) ) agreed that 550 applied and 225 didn't apply.
Article 225 does apply. 550 (being in chapter 5) may modify the requirements, but it being a mobile home does not throw Chapters 1 - 4 out the window. Look at it this way: Do we not have to secure the raceways containing these feeders? This section says nothing about securing and supporting.

Yes, we do, because Chapter 3 still applies. As does Chapter 2. As does Article 225.

For trailers 225 only applies to items not covered by 550.
550.32 & 33 covers services and feeders and nowhere restricts the number to one single supply.
No, no, no, that's backwards: Nowhere does it permit more than one supply. That's what we'd have to see to override the requirements of 225. There is no language, so there is no permission.

550.33(A) Feeder Conductors. Feeder conductors shall consist of either a listed cord, factory installed in accordance with 550.10(B), or a permanently installed feeder...

This structure is only allowed one feeder unless this section said otherwise. It doesn't. In fact, it refers to a singular feeder, in line with the requirements of 225.

So says the housemonkey. :)
 

Smart $

Esteemed Member
Location
Ohio
georgestolz said:
...Nowhere does it permit more than one supply....
George,

Let's try this from a different angle. I'm not thinking all that clearly at this time, so it may actually be to your advantage :D

Let's say you have one building on a property with one service (pretty typical, eh?). You put one service disconnecting means on the outside of that building. How many feeders can you run off the load side of the service disconnecting means into the building?
 
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