contractors on-site office trailer

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ronbannon

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I am looking for feed back. NEC 2002
I am inspecting a job site 1-temporary service , 2- office trailer.
The temporary service I inspected per 527.4 (A) which refers back to 230.
The contractors on-site office trailer I am using 550.4 which specifies the contractors on-site office than 550.32 for disconnecting means with in sight
and than 550.33 for type of feeders. Which calls for 4 insulated conductors. I believe that it is calling for an insulated ground,2 hots 1 neutral 1 ground.
 
Jim W in Tampa said:
All i am saying is the 2 are wired about the same.They both need 4 wires
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If it is not covered by 550 (IMO it's not) than the normal rules for separate buildings apply.

The feeder could be either 3 or 4 wire.

I wire job trailers four wire but there are options.
 
I need better proof that what you say is a fact. I know you mentioned it is your opinion (of which I highly respect), but I need more info before I can agree with your belief.
I will email a few people I know who are pretty good with this stuff and see what they have to say. You may be correct.

The wording in either the scope or 550.4 may need some clarification.
 
Pierre as my post in the linked thread indicated I was unsure myself until I read it using Charlie's rules. Perhaps it is not the intent but that is how I read it. :)

First and foremost the entire Article deals with Mobil homes which they went on to describe as a structure designed to be used as a dwelling unit.

If the job trailer was never designed to be a dwelling unit it can not be mobile home per the definition.

As I mentioned in the other thread I am interested in how others read it. :)

JMO, Bob
 
The debate of is it a mobile home or an office is redundant once you go past the first means of disc. it has to be 4 wired.
 
allenwayne said:
The debate of is it a mobile home or an office is redundant once you go past the first means of disc. it has to be 4 wired.
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No it does not have to be four wire.

You could quite easily apply 250.32(B)(2) and feed it three wire.
 
550.4 General Requirements

550.4 General Requirements

under general requirerments mobile home not intended as a dwelling.It list some examples contractors on-site offices. So does that mean it has to be a mobile home first or can it be a onsite contractors office trailer.
designed for the purpose.
So would it require an insullated ground.
 
Re: 550.4 General Requirements

Re: 550.4 General Requirements

ronbannon said:
under general requirerments mobile home not intended as a dwelling.It list some examples contractors on-site offices. So does that mean it has to be a mobile home first or can it be a onsite contractors office trailer.
designed for the purpose.
So would it require an insullated ground.
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That is the big question here. We need to try and find the answer.

I will say that until I read your original post, I treated job trailers like new services, or secondary buildings depending on the situation. Now you have me wondering?
 
Bob,

I would agree with everything you said, except, the definetion of Moble

Home doesn't say dwelling unit it says dwelling and without that 'unit'

after it the meaning changes. I say the office dwelling must follow 550.

comments welcome.
 
iwire said:
allenwayne said:
The debate of is it a mobile home or an office is redundant once you go past the first means of disc. it has to be 4 wired.
Click to expand...

No it does not have to be four wire.

You could quite easily apply 250.32(B)(2) and feed it three wire.
Click to expand...

What constitutes the grounding electrode in these units. The reason I am asking is that it is not unusual to have a trailer/mobile office/mobile home set up on a temporary basis with the only utility supplied is electrical. I will agree that a pair of ground rods could be driven, but that sure seems to me a waste of time. :)
 
If you picked up the first part of 550.4(A) and placed it in 550.2, would you answer the question differently ?

You have separate definitions for Mobile Home, Mobile Home Accessory Building or Structure, Mobile Home Park, and Mobile Home Service Equipment. What if there was a separate definition for Mobile Home Not Intended as a Dwelling Unit ?

550.2 Definitions
Mobile Home Not Intended as a Dwelling Unit. A mobile home not intended as a dwelling unit ? for example, those equipped for sleeping purposes only, contractor?s on-site offices, construction job dormitories, mobile studio dressing rooms, banks, clinics, mobile stores, or intended for the display or demonstration of merchandise or machinery.

Then 550.4(A) would read
A Mobile Home Not Intended as a Dwelling Unit shall not be required to meet the provisions of this article pertaining to the number or capacity of circuits required. It shall, however, meet all other applicable requirements of this article if provided with an electrical installation intended to be energized from a 120-volt or 120/240-volt ac power supply system. Where different voltage is required by either design or available power supply system, adjustment shall be made in accordance with other articles and sections for the voltage used.

Would this change your opinion of what would be required ?

David
 
It might, but that is like saying if black was white would you call it light. :)

550 does not have a definition of a mobile home not intended as a dwelling unit.
 
I would say that you have found a loop hole. And I'm not saying that a loop hole is not acceptable, a loop hole is totally fine. As long as the meaning is clear enough to understand as written, then there's no need for interpretation. If the code panel wants it to say differently, they will need to change it.

The panel provided the definition, now they have to live with that definition.

Having said that, I still suspect that what I proposed above is what they were trying to establish as the rule. I don't see any reason to treat one job trailer differently than another just because it started its life designed as a dwelling. The atoms that travel down the grounding wire don't know that the job trailer was originally designed to be a dwelling.

David
 
Bob,

The definetion in 550 for Moble home, does not call it a dwelling UNIT,

it just says 'dwelling'.

Using Charlies Rules it says what it says, Dwelling, not Dwelling Unit, I

know you can see it.

So a moble home does not have to start out as a dwelling unit, and that

makes the rest of the article make sense.
 
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