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-   -   mobile home service to bond or not to bond (http://www.diychatroom.com/f18/mobile-home-service-bond-not-bond-66836/)

rikmac 03-15-2010 01:01 PM

mobile home service to bond or not to bond
 
Hello peeps i have been a avid reader of this forum in the past 3 weeks do to the renovation of a mobile home i decided to start. The mobile home in question is 50x10 around 1960ish i dont recall of the top of my head but its pretty old. Anyway i decided to live in it so i ripped out all the old wireing and put in all new stuff then came the panel box.Now in my quest for knowledge i have an answer to the problem but i would like to see if im right before i implement it .I have photo documented my adventure and would like to share if anyone else has the same predicament and cant find anything on it so here is the situation.

1st. 50 feet from the trailor is the meter 2 fuse plugs one 50amp and 1 30amp i think couldnt really read the fuse

2nd. comming up under the trailor is a 3-Pole, 3-Wire, (NEMA 10-50r receptacle) and another outlet for the 30amp 2 wires no ground ihave questions still about that but has nothing to do with this post

3rd.The old lug box had the 3 wires ran into it with the 2 hots on a 50amp breaker feeding it 3 20amp breakers feeding the whole place and a side box with a glass fuse feeding power to the hot water heater the box was not bonded to the neutral and had ground running to earth ground

Now should i bond the new box or not bond it

Billy_Bob 03-15-2010 02:01 PM

Bond (James Bond! :))...

Seriously, the grounds need to be bonded to neutral at some point. This assures that if a hot conductor touches a ground, then the breaker for that hot conductor will trip.

As to NEC and the new work you did and if any changes need to be made to the meter/outlet? (Someone should be along for that...)

nap 03-15-2010 02:31 PM

No, you do not bond the neutral and ground in the panel in the trailer. Your service disconnect is at the pedestal and that is the only place you bond the neutral and grounds.


You should then have a 4 wire feeder from the pedestal to the trailer. The trailer does need ground rods and the ground in the panel is connected to the rods.

you do need a grounding electrode system for the pedestal as well.

Stubbie 03-15-2010 03:57 PM

First nap is absolutely correct with his advice. Second please take us on your photo adventure including the fuse panel out at the meter because I have 101 questions about what was existing and what is going to be new. You say you are replacing everything with new so I am assuming that also means the service equipment panel out at the meter pedestal and the wire from meter and service equipment to the mobile home trailer 50 amp receptacle. As Nap said you need 4 wires (H-H-N-Grd) from the service equipment at the meter power pedestal to the 50 amp receptacle not 3 like you say you have now. And there should not be an extra 30 amp receptacle feeding power into the trailer. You say you have a 50 amp fuse and a 30 amp fuse at the meter service equipment. They should both be 50 amp if that trailer is being fed a 120/240 volt service.

I hate coming behind people and their trailer (mobile) homes some of the screwest...cheesiest wiring I have ever encountered was with these portable dwellings.....:)

rikmac 03-15-2010 04:27 PM

maby i should have clarified a little i will not be replaceing the wiring or meter from the meter to the trailer (little bit out of my comfort zone ) and anyways i would think the park would be in charge of that . the plugin is a 3 prong not 4 right now. my photo montage will come later tonight im at work now
the 30 ft that ran under the trailor from th plug in is interesting i think it is like 4 gauge aluminum wire connected to 6/3 copper at the back of the trailer where it came in and connected to the panel.ill have to get a pick of the meter and stuff didnt think of the 2 fuses for the 240 volt make me wonder where those 2 wires are comming from :laughing:

kbsparky 03-15-2010 11:47 PM

Quote:

Originally Posted by nap (Post 414931)
..... The trailer does need ground rods and the ground in the panel is connected to the rods.......

I have never installed ground rods at a mobile home. Care to provide a Code section to back up this assertion?

rikmac 03-16-2010 12:36 AM

alright gonna try to post some pics

first should be ground pole and the mysterious plug wires
http://img689.imageshack.us/img689/9663/picture1198.jpg

next is the plug that brings power to the trailer
http://img689.imageshack.us/img689/4718/picture1196.jpg

here is the infamous breaker box
http://img97.imageshack.us/img97/2487/picture1195.jpg

rikmac 03-16-2010 12:38 AM

ground wires running to the plug :laughing:
http://img716.imageshack.us/img716/9813/picture1199.jpg

nap 03-16-2010 12:38 AM

Quote:

Originally Posted by kbsparky (Post 415220)
I have never installed ground rods at a mobile home. Care to provide a Code section to back up this assertion?


is there some reason 250.32 would not apply that you are aware of?

Stubbie 03-16-2010 02:35 AM

I think the only way a ground rod is used is if the mobile home service equipment is more than 50 feet from the mobile home and a service rated disconnect is installed between the home and the service equipment but not more than 30' from the home. In which case you would use grounding in accordance with 250.32 at the disconnect location. Otherwise no ground rod at the mobile home panel.

nap 03-16-2010 10:41 AM

I don't see anything in 250.32 or anything in 550.xx that would allow that exception Stubbie. If you have some specific sections that you believe would allow this, please post them.


250.32 clearly states that all separate buildings fed through a branch circuit or feeder, unless there is only a single branch circuit (including MWBC) must have a grounding electrode.

the trailer is a separate building or structure simply by virtue of it not being physically connected to the power pedestal. Since there is a distribution panel in the trailer, it is being fed with a feeder and not a branch circuit.


I see no reason why 250.32 would apply to this situation any differently than a situation where you would have a farm stand service and feeders to separate buildings or structures.

Billy_Bob 03-16-2010 11:16 AM

This is an interesting situation in that the mobile home is owned, and the plug in and meter are rented!

And that the mobile home is "plugged in" like an appliance, and in other cases like this, that is where the NEC ends and UL begins...

So I searched google.com and found this which apparently covers the electrical in manufactured homes?...

["Any Manufactured Home, Mobile Home, Park Model or Travel Trailer, moved to or within Coconino County for set-up and used for habitation for residential purposes shall have affixed upon it the proper Arizona Identification for Manufactured and Mobile Homes, showing it to be an Approved HUD unit, or the proper American National Standard Institute (ANSI) Label for Park Models and Travel Trailers. (UBC 101 and in accordance with the Coconino County Zoning Ordinance)."]

http://www.coconino.az.gov/uploadedF...0checklist.pdf

Stubbie 03-16-2010 03:08 PM

I can't say there is any specific in the nec under art.550 that specifies a ground rod cannot be or must be or is not installed at the mobile home panel board. My understanding is that you do not in order to facilitate the "mobile" aspect of the home. In other words you can unplug the thing and hook up to it and drive away with the home.

My interpretation of 550.16 which also includes the non energized electrical parts and metal frame for equipment grounding and 550.32(A) is that no ground rod is installed at the mobile home panel. The service equipment for the mobile home ... which is specifically not allowed to be attached to the mobile home to keep it mobile has the only ground rod.

I'm certainly no expert on mobile homes but I have done a few and I have never encountered or installed a ground rod and grounding conductor to the inside grounding bar in the distribution panel of the mobile home. Our county guidelines do not require it and it isn't wanted by our inspectors.

I do not think it is not allowed if you wanted to install one. I also do not think 250.32 applies to mobile homes other than the disconnecting means located outside not attached to the mobile home.

wirenut1110 03-16-2010 04:19 PM

I've never done ground rods at a mobile home either, just at the service. 4 wire to the "trailer" panel and at least a #8 copper bond to the frame.

Most mobile homes have the rods with the strapping that anchor it the ground. I believe that's what's taking place of grounds rods and to how those are attached to the frame.

nap 03-16-2010 05:04 PM

Quote:

Originally Posted by Stubbie (Post 415474)
I can't say there is any specific in the nec under art.550 that specifies a ground rod cannot be or must be or is not installed at the mobile home panel board. My understanding is that you do not in order to facilitate the "mobile" aspect of the home. In other words you can unplug the thing and hook up to it and drive away with the home.

My interpretation of 550.16 which also includes the non energized electrical parts and metal frame for equipment grounding and 550.32(A) is that no ground rod is installed at the mobile home panel. The service equipment for the mobile home ... which is specifically not allowed to be attached to the mobile home to keep it mobile has the only ground rod.

I'm certainly no expert on mobile homes but I have done a few and I have never encountered or installed a ground rod and grounding conductor to the inside grounding bar in the distribution panel of the mobile home. Our county guidelines do not require it and it isn't wanted by our inspectors.

I do not think it is not allowed if you wanted to install one. I also do not think 250.32 applies to mobile homes other than the disconnecting means located outside not attached to the mobile home.


250.32 simply states "building or structures fed by feeders or branch circuits" I see no way to not include them.

I think the only way you could remove it from the requirement to use one would be to consider the home an appliance and not a building but I think that is pushing it a bit far.

and what 550.16 is speaking to is not bonding the steel frame or the frame of any appliances to the neutral (grounded) conductor if the service entrance eqipment is adjecent to (not connected physically) to the home. It goes on to say that if the panel board inside the home is also considered the service entrance equipment, you must bond the neutral and grounding bus (typical for any service entrance equip)

it also states the the appliance frames and other steel must be bonded to the grounding bus in the house panel even with a separate service pedestal.

and to 550.32

A (controls if the service equip is not mounted on the building)

says grounding at the disconnecting means shall be per 250.32. It speaks to nothing about grounding for the building itself.

and B states that if the service equipment is mounted on the building, grounding is per 250 just like any other building.

disconnecting or even removing a ground rod would be no more work than installing axles and wheels back onto the unit, removing skirting, installing a hitch and lights. I think that is a pretty weak argument stubbie.:wink:


so, I have yet to hear any argument that a manufactured home should not be considered to be a "building or structure" per 250.32.

but, since you want to consider the temporary point:

do you not drive ground rods for a temporary service such as for a construction site?

If powering temporary office trailers from a farm stand type service at a construction site, do you not drive ground rods?


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