Job Trailer Wiring Method

Status
Not open for further replies.
A

alaskan JW

Member
Location
Anchorage,Ak
I am wiring up a new job trailer and am wondering if MC is allowed for my branch circuits. I believe i have seen MC used before. If not i will use EMT.
Thanks!
 
The MC will be surfaced mounted, forgot to the mention that earlier.
I didn't know what section to look under for acceptable wiring methods, section 550 does not
cover it?
 
250.32 Buildings or Structures Supplied by a Feeder(s)
or Branch Circuit(s).
(A) Grounding Electrode. Building(s) or structure(s) supplied
by feeder(s) or branch circuit(s) shall have a grounding
electrode or grounding electrode system installed in
accordance with Part III of Article 250. The grounding
electrode conductor(s) shall be connected in accordance
with 250.32(B) or (C). Where there is no existing grounding
electrode, the grounding electrode(s) required in 250.50
shall be installed.
 
Unless you are going to remove the wheels, and or block up this trailer at every site it is taken to why is it any different than any other portable equipment? It is most likely connected via cord and plug. If grounding electrodes are required they should go at the permanently connected equipment supplying the receptacle. If it is not cord and plug connected then it is like any other permanent wired building or structure.


As far as job trailer not being a mobile home, I have seen a couple that this would be debatable, maybe not necessarily meeting NEC definition of mobile home but general definition of job trailer vs home. Seen some that are nicer than some homes inside. One local homebuilder has air conditioner, refrigerator, maybe a few other comforts. They always take their breaks in there.
 
kwired said:
As far as job trailer not being a mobile home, I have seen a couple that this would be debatable,
Click to expand...

If it is a mobile or manufactured home it will have a label that states that.

Most job trailers are Manufactured Buildings and Article 545 applies. :)
 
iwire said:
If it is a mobile or manufactured home it will have a label that states that.

Most job trailers are Manufactured Buildings and Article 545 applies. :)
Click to expand...


There is not much to 545. The OP question is not really answered in 545.

I do agree if it is a mobile or manufactured home it will have a label.

I think Ch 1 - 4 are all OP needs concerned about. I also think he can use any wiring method he wants as long as requirements for the method he chooses are met. This is not one of those occupancies that prohibits the use of a particular method like we have with NM cable in places of assembly or something like that.
 
kwired said:
There is not much to 545. The OP question is not really answered in 545.
Click to expand...

I did not say there is or that it did.

Just pointing out most job trailers are covered by 545.


I think Ch 1 - 4 are all OP needs concerned about. I also think he can use any wiring method he wants as long as requirements for the method he chooses are met.
Click to expand...

I agree.
 
Are they buildings or are they vehicles/vehicle accessories?

That could make a big difference in what article applies, or even if NEC applies at all.
 
David A Engelhart said:
Is this "Job Trailer" not an onsite contractors trailer as described in 550.4(A)?
Click to expand...

550.4 A applies to "mobile homes" not intended for use as a dwelling.

Look at definition of mobile home in 550.2, if the trailer does not fit that definition it is not a mobile home.

Since the definition in 550.2 includes the words "used as a dwelling" it seems contradictive when you read 550.4 A. I think 550.4 A is talking about a structure that qualifies as a mobile home but is not used as a dwelling.

So if the job trailer is actually a mobile home but not used as a dwelling then this applies. This may be more likely for a jobsite office, or dormitory than for a tool or supply trailer.
 
I know this confuses many as to what a job trailer is, the most simple way to describe which article to use is the look into the definition of what a mobile home is:

550.2 Mobile Home. A factory-assembled structure or structures transportable in one or more sections that is built on a permanent chassis and designed to be used as a dwelling without a permanent foundation where connected to the required utilities and that includes the plumbing, heating, air-conditioning, and electric systems contained therein.
For the purpose of this Code and unless otherwise indicated, the term mobile home includes manufactured homes.
Click to expand...

The above in red is the key, if you take a mobile home/manufactured home as per the above definition (designed as a dwelling) and turn it into a job trailer then 550.4(A) applies, if you are wiring a trailer/building that was designed to be used for a job trailer from the beginning then it is a 545 building, this is the whole reason for the 550.4(A) rule, because a trailer made to be used as a dwelling will have circuits and designs not required in a 545 building, and 545 will require or allow things that 550 would not.

I type too slow, but at least Kwired and I think alike:angel:
 
Last edited:
kwired said:
There is not much to 545. The OP question is not really answered in 545.

I do agree if it is a mobile or manufactured home it will have a label.

I think Ch 1 - 4 are all OP needs concerned about. I also think he can use any wiring method he wants as long as requirements for the method he chooses are met. This is not one of those occupancies that prohibits the use of a particular method like we have with NM cable in places of assembly or something like that.
Click to expand...

very correct, as found in 545.4(A)
 
The key area to look for description of type of use is located on the backside of the panel cover door. In the picture attached, this type of construction trailer is an industrialized building which is a manufactured building.

DSCN1466.jpg
 
RUWired said:
The key area to look for description of type of use is located on the backside of the panel cover door. In the picture attached, this type of construction trailer is an industrialized building which is a manufactured building.

View attachment 5772
Click to expand...

But we must remember not all states will have that label in the same place, while most do put it by the panel, some are a metal plate on the back corner of the building like HUD MHs are.

But it doesn't really mater, as if it is a MH but not used for a dwelling then 550.4(A) will require it to be CH3 wired for the purpose it will be used for, here we have MH's converted to hot dog stands.

One example is mobile classrooms, if they have an occupancy of more then 100 then no NM or PVC.
 
Last edited:
An interesting grounding detail between the two types of listed building is the use of an insulated ground conductor in the supply conductors. The listed mobile homes require it, and the manufactured buildings don't.
 
Status
Not open for further replies.
Top