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Intersystem grounding bar #206932 09/02/12 07:55 PM
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George Little Offline OP
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Is an "Intersystem Bonding Termination" bar needed at a mobile home park,if so where do you install it? How about do you need a ground rod at the mobile home?


George Little
2017 / 2014 NEC & Related Books and Study Guides
Re: Intersystem grounding bar [Re: George Little] #206933 09/02/12 09:24 PM
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gfretwell Offline
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I suppose it depends if these are park model mobile homes or RVs.
Around here, if it is being permitted as a dwelling unit it is treated like a house. If you rtake the wheels off, it is permitted.
We drive a rod at the MH and these days I would want to see the IBT right there where the service feeder enters the unit. That is also where the ground rod typically goes.

If this is a cord and plug connected RV, we stop at the power post. If the park is providing phone and cable/satellite, the IBT would be there.


Greg Fretwell
Re: Intersystem grounding bar [Re: George Little] #206934 09/03/12 08:10 AM
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George Little Offline OP
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Thanks Greg. I think I can agree with you to a point. I'm wrestling with the code reference lacking related to driving a rod at the MH v. the pedestal. My feeling is that the definition of the IBT leaves us hanging when it comes to MHs. I also can find no code reference asking for a rod or any other electrode at the MH. In the real world they drive a rod at the MH and connect it to the grounding buss in the panel or to the frame of the home. My feeling is that the IBT should be at the demark for the system, phone, cable etc. This creates a problem if it is located at the pedestal because the cable or phone line must then extend to the MH from the pedestal. As far as taking the wheels off, around here, it's still a MH with or without wheels. Thanks for your comments as usual.


George Little
Re: Intersystem grounding bar [Re: George Little] #206936 09/03/12 01:38 PM
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gfretwell Offline
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The current wind code is making it hard to set any kind of mobile home so we see a lot of "RVs".
They still need a permit of this is not cord and plug connected and if they take the wheels off.
It is considered a manufactured home and it has to be certified for the applicable wind code. (140-170 MPH in this county) That severely limits any new installations.
http://gfretwell.com/electrical/2012%20wind%20code%20map.jpg

This is defined in 550.33 and (A)(2) will get you to the ground rod.

Quote
550.33 Feeder.
(A) Feeder Conductors. Feeder conductors shall comply with the following:
(1) Feeder conductors shall consist of either a listed cord, factory installed in accordance with 550.10(B), or a permanently installed feeder consisting of four insulated, color-coded conductors that shall be identified by the factory or field marking of the conductors in compliance with 310.12. Equipment grounding conductors shall not be identified by stripping the insulation.
(2) Feeder conductors shall be installed in compliance with 250.32(B).


Greg Fretwell
Re: Intersystem grounding bar [Re: George Little] #206937 09/03/12 01:49 PM
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renosteinke Offline
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I think you're right, and your question cannot be answered by parsing code language.

Nor should it; after all, the NEC is neither design manual nor instruction book. It says so itself. One is, after all, to already have mastered the trade. So, we have to ask 'what are we trying to accomplish?' in order to determine what we SHOULD do.

(That the code is a nightmare of conflicting theory and contradictory language, especially in regards to grounding, should be no surprise).

So, my first question is: what is the IGB for? Why, it's to provide the cable, satellite, telephone, alarm, and who knows what (Apple will invent this Fall) an easy place to connect to the grounding network.

Let's also ask, just to stir the pot, what the ground rod is for.

I'd say that both the IGB and the ground rod are there for lightning. Let's start at that point.

So - despite the absolute lack of any provision in the construction of mobile homes- the trailer really ought to have a ground rod, tied into the panel in the trailer. Just like any other 'detached structure.' I do agree that this is not what the NEC requires, which might explain the lack of any such provision on trailers.

Next point: the IGB. We need to ask: where will these things be attached? If the satellite dish is mounted on the same pole as the service to the trailer, then there needs an IGB there. If you're hanging things from the trailer, it goes there (and lands on the trailer panel). One might need an IGB at both locations.

Of course, trailers lack any provisions for running anything to the panel, so it appears the trailer gods have not considered this matter.

You're right; the code panels have dropped the ball here.

Re: Intersystem grounding bar [Re: George Little] #206938 09/03/12 03:35 PM
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gfretwell Offline
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If the "trailer" is served by a hard wire (chapter 3) feeder 550.33 referencing 250.32(B) requires that ground rod.
Then you get into parsing the difference between a mobile home and a manufactured home. Most of the AHJs around here do not make that distinction. If you take the wheels off and tie it down, it is a manufactured home and treated, pretty much like, any other structure.

We are not really setting enough of them to create a precedent these days.



Greg Fretwell
Re: Intersystem grounding bar [Re: George Little] #206939 09/03/12 04:57 PM
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Posts: 7,233
HotLine1 Offline
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My take is a IBT at the 'trailer', as that is where the cable, telco, dish, & etc. guys install the various demarcs.

'Trailers' are hard wired, wheels off, anchored, skirted. Electrical service is independent for each, POCO meter, 100 amp disco at the pole, and 4 wire feeder (PVC/THWN) to the installed panel. Grd rod, IBT, bond to frame.

Trade practice & accepted IMHO


John
Re: Intersystem grounding bar [Re: George Little] #206941 09/03/12 08:02 PM
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gfretwell Offline
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John and I am on the same page here. This is a dwelling unit if it is permanently installed.

I guess but it is still moot here. The last I heard it is virtually impossible to get a mobile home permit. They have to meet wind code after Charley. They will all be cord and cap connected RVs (rolling stock). Just about the time the trailer guys had a 130 MPH mobile home, they bumped our code up to 150.
We are also zoning mobile home parks away as fast as attrition makes them go away. It isn't even a cheap place to live anymore because the dirt is worth more to a buyer than what you think the rent should be.
When I moved here 30 years ago, I could buy a real CBS house on a third of an acre for what a double wide was in a high end park where you didn't even own the land.



Greg Fretwell
Re: Intersystem grounding bar [Re: George Little] #206944 09/04/12 05:38 PM
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George Little Offline OP
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Okay, now I know what goes on in the real world (considering FL as part of it) I'll look in Soares and find out what the IAEI thinks is required.

Greg makes a valid code reference to 250.32(B). I can remember when there were Parks that only required an electrode at the pedestal. I let you know what Soares says.

I can remember that there are lugs on the underside frame of of the homes I've been involved in.

This still doesn't address the location of the IBT. I maintain that the IBT should be at the Service Disconnect or in the case of the MH, at the disconnect for the MH. So any cable, phone, antenna should be at the home disconnect not at the home. What say you?

Last edited by George Little; 09/04/12 05:43 PM.

George Little
Re: Intersystem grounding bar [Re: George Little] #206945 09/04/12 07:28 PM
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gfretwell Offline
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My decision on the IBT would be where the satellite dish is and where the telco/cable Dmark is.


Greg Fretwell
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