mobile home & ground rods

[hurk27]

That's an interpretation. Read the following portion...

Subpart I?Electrical Systems
? 3280.801 Scope.
(a) Subpart I of this part and Part II of Article 550 of the National Electrical Code (NFPA No. 70?2005) cover the electrical conductors and equipment installed within or on manufactured homes and the conductors that connect manufactured homes to a supply of electricity.
(b) In addition to the requirements of this part and Part II of Article 550 of the National Electrical Code (NFPA No. 70?2005), the applicable portions of other Articles of the National Electrical Code must be followed for electrical installations in manufactured homes. The use of arc-fault breakers under Articles 210.12(A) and (B), 440.65, and 550.25(A) and (B) of the National Electrical Code, NFPA No. 70?2005 is not required. However, if arc-fault breakers are provided, such use must be in accordance with the National Electrical Code, NFPA No. 70?2005. Wherever the requirements of this standard differ from the National Electrical Code, these standards apply.

An interpitation of the above in red, seems pretty clear:happyyes:

 

[don_resqcapt19]

What happened to the statement that was used here all the time; :?
“The NEC is a permissive document, if it don’t say you can’t then you can”

Would this not apply here? The fact that the code is silent about the electrode system at the mobile home means one is not required.

The code is not silent on the issue. The rules in Chapter 5 can modify those in Chapters 1 through 4. The rule in 250.32 clearly requires a grounding electrode at the mobile home. The issue is if there is actual wording in Article 550 that modifies the rule in 250.32.


Sorry...posted before reading the complete thread.

 

[david]

The code is not silent on the issue. The rules in Chapter 5 can modify those in Chapters 1 through 4. The rule in 250.32 clearly requires a grounding electrode at the mobile home. The issue is if there is actual wording in Article 550 that modifies the rule in 250.32.


Sorry...posted before reading the complete thread.

550.16 Grounding.
Grounding of both electrical and nonelectrical metal parts in a mobile home shall be through connection to a grounding bus in the mobile home distribution panelboard. The grounding bus shall be connected through the green-colored insulated conductor in the supply cord or the feeder wiring to the service ground in the service-entrance equipment located adjacent to the mobile home location.

 

[don_resqcapt19]

550.16 Grounding.
Grounding of both electrical and nonelectrical metal parts in a mobile home shall be through connection to a grounding bus in the mobile home distribution panelboard. The grounding bus shall be connected through the green-colored insulated conductor in the supply cord or the feeder wiring to the service ground in the service-entrance equipment located adjacent to the mobile home location.

It doesn't say don't install the grounding electrode that is required by 250.32. Maybe that was the intent, but like a lot of code sections, the wording does not match the intent.

 

[david]

I know how the grounding electrode conductor can be routed out-side of a manufactured home when it involves a service disconnect. Connecting a grounding electrode conductor to a service neutral has location options like the meter enclosure, the service drop any location outside the manufactured home.

Those of you who are going to require a grounding electrode connection to the main disconnect equipment ground bus when supplied by a feeder how are you going to route the grounding electrode conductor outside the manufactured home? Not saying it is impossible just wondering what you have in mind

 

[Smart $]

3) Service equipment installed on the manufacturedhome in accordance with Article 230 of the National Electrical Code, NFPA No. 70?2005, and the following requirements:

Yes... and your point???

 

[Smart $]

... Wherever the requirements of this standard differ from the National Electrical Code, these standards apply.

An interpitation of the above in red, seems pretty clear:happyyes:

But there is nothing in "this standard" which differs from NEC 250.32 Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s).

 

[Smart $]

550.16 Grounding.
Grounding of both electrical and nonelectrical metal parts in a mobile home shall be through connection to a grounding bus in the mobile home distribution panelboard. The grounding bus shall be connected through the green-colored insulated conductor in the supply cord or the feeder wiring to the service ground in the service-entrance equipment located adjacent to the mobile home location.

It doesn't say don't install the grounding electrode that is required by 250.32. Maybe that was the intent, but like a lot of code sections, the wording does not match the intent.

I agree. What is stated in 550.16 is irrelevant to the installation of the building GES per 250.32.

90.3 Code Arrangement. This Code is divided into the
introduction and nine chapters, as shown in Figure 90.3.
Chapters 1, 2, 3, and 4 apply generally; Chapters 5, 6, and 7
apply to special occupancies, special equipment, or other special
conditions. These latter chapters supplement or modify the
general rules. Chapters 1 through 4 apply except as amended
by Chapters 5, 6, and 7 for the particular conditions.

 

[renosteinke]

Mind you, those who believe that a mobile home needs two ground rods ... one at the pedestal and one at the trailer itself ... are alos opening another few cans of worms.

The first is the recent code change requiring TWO ground rods for each 'structure.' With a minimum 6-ft distance between them, that can get interesting. I would hazard a guess that most pedestals are within six feet of the trailer- trailer lots are not known for being spacious.

The next issue is connecting the rods of both structures together as a common ground network. As others have stridently posted in another thread, this requires a direct connection- the green wire of the feeder is not allowed to be considered as part of the GEC network. So, we've got ANOTHER trench to dig.

I think it's time that at least one of these code zealots produce pictures of just ONE trailer that is hooked up that way- two rods at the pedestal, two rods at the trailer, all connected by a GEC to the pedestal. Just one. Until then, I'll have to insist that the above view is either an unintended extension of the NEC, or a deliberate 'stealth' change (not addressed in any code-update book) .... I cannot accept that EVERY electrician and EVERY inspector has had it 'wrong' all these years.

 

[iwire]

Mind you, those who believe that a mobile home needs two ground rods ... one at the pedestal and one at the trailer itself ...

That is what we are saying and it is what the words in the NEC currently require.

I think it's time that at least one of these code zealots produce pictures of just ONE trailer that is hooked up that way- two rods at the pedestal, two rods at the trailer, all connected by a GEC to the pedestal. Just one. Until then, I'll have to insist that the above view is either an unintended extension of the NEC, or a deliberate 'stealth' change (not addressed in any code-update book) .... I cannot accept that EVERY electrician and EVERY inspector has had it 'wrong' all these years.

This is the NEC section of an NEC website, talking about the code and what it actually says here on this forum does not make anyone a zealot.

The OP did not ask how you do it, or how I do it, or how effective rods may be, or how close they may be.

They asked a code question.

 

[iwire]

I agree. What is stated in 550.16 is irrelevant to the installation of the building GES per 250.32.

And what I have been saying since the start.

 

[david]

I agree. What is stated in 550.16 is irrelevant to the installation of the building GES per 250.32.

Only if you ignore that 550.16 is specific to mobile homes and the portion posted tells us how to ground a main distribution panel in a mobile home when supplied by a feeder.

? Yes... and your point???
The only time a grounding electrode conductor is mention in article 550 is when the service equipment is allowed in or on a manufactured home. And there are specific instructions on how the conductor is to be routed when it is associated with a manufactured home,

There are no such instructions when the supply involves a feeder
Why because article 550 does not require a grounding electrode conductor to the main distribution panel in a manufactured home unless that distribution panel is also the service disconnect for the manufactured home.

The NEC must consider there to be a hazard involved in routing a grounding electrode conductor on the interior of a manufactured home. The only way to connect a grounding electrode conductor to an interior distribution panel is to route it in the interior of the manufactured home.

So lets ignore the fact that the NEC intended an insulated equipment ground to be the connection from the distribution panel to the grounding electrode at the service, or if the service is directly associated with the structure to route it on the exterior of the structure

 

[kwired]

Mind you, those who believe that a mobile home needs two ground rods ... one at the pedestal and one at the trailer itself ... are alos opening another few cans of worms.

The first is the recent code change requiring TWO ground rods for each 'structure.' With a minimum 6-ft distance between them, that can get interesting. I would hazard a guess that most pedestals are within six feet of the trailer- trailer lots are not known for being spacious.

The next issue is connecting the rods of both structures together as a common ground network. As others have stridently posted in another thread, this requires a direct connection- the green wire of the feeder is not allowed to be considered as part of the GEC network. So, we've got ANOTHER trench to dig.

I think it's time that at least one of these code zealots produce pictures of just ONE trailer that is hooked up that way- two rods at the pedestal, two rods at the trailer, all connected by a GEC to the pedestal. Just one. Until then, I'll have to insist that the above view is either an unintended extension of the NEC, or a deliberate 'stealth' change (not addressed in any code-update book) .... I cannot accept that EVERY electrician and EVERY inspector has had it 'wrong' all these years.

The issue is whether the pole/pedestal/etc. is considered a separate structure from the mobile home. If it is you wouldn't need to connect the electrodes at the first structure to the second structure via a separate GEC, you just install a separate GEC at each location to the electrodes at each location. Same as a house that feeds a detached garage.

No one has presented any concrete information either way if they are separate structures or if they are considered one for the purpose of the grounding electrode system. The only thing different between the mobile home and pedestal and the house and detached garage is the disconnect for the mobile home has to be within 30 feet of the mobile home. The house and detached garage could be inches away from each other, or could be hundreds of feet from each other.

 

[iwire]

So lets ignore the fact that the NEC intended an insulated equipment ground to be the connection

Exactly that, let us ignore anyone's idea of intent and concentrate on what it actually says.

Intent is not enforceable and should not be.

 

[iwire]

The only thing different between the mobile home and pedestal and the house and detached garage is the disconnect for the mobile home has to be within 30 feet of the mobile home. The house and detached garage could be inches away from each other, or could be hundreds of feet from each other.

Thank you, I was tempted to point that out myself.

 

[don_resqcapt19]

...The next issue is connecting the rods of both structures together as a common ground network. As others have stridently posted in another thread, this requires a direct connection- the green wire of the feeder is not allowed to be considered as part of the GEC network. So, we've got ANOTHER trench to dig. ...

Second buildings or structures do not require an additional connection to the first building. The grounding electrode at the second building is bonded to the the EGC that is run with the supply to that second building or structure.

 

[pfalcon]

550.16 Grounding.
Grounding of both electrical and nonelectrical metal parts in a mobile home shall be through connection to a grounding bus in the mobile home distribution panelboard. The grounding bus shall be connected through the green-colored insulated conductor in the supply cord or the feeder wiring to the service ground in the service-entrance equipment located adjacent to the mobile home location.

It doesn't say don't install the grounding electrode that is required by 250.32. Maybe that was the intent, but like a lot of code sections, the wording does not match the intent.

Exactly that, let us ignore anyone's idea of intent and concentrate on what it actually says.
Intent is not enforceable and should not be.

See emphasis in David's quote.

Don makes a good point that it doesn't explicitly remove 250.32 which is a poor choice in the wording. However, it does explicitly state that you're to do it in a specific manner. All my language training says that means "instead of" not "in addition to". Consider the wording side by side:

1) ... shall be through ...
2) ... shall also be through ...
3) ... may be through ...
4) ... may also be through ...

All provoke different meanings. I believe the first is a replacement eliminating any prior (250.32) requirement.

1) required replacement
2) required addition to original requirement
3) optional alternative to replace original requirement
4) optional addition to original requirement

 

[renosteinke]

Don, I agree with you, and that's certainly what I've been doing ... letting the EGC of the feeder provide the connection to the grounding network of the main building.

Yet, this very forum, quite recently, said differently. I believe it was Bob (Iwire) who led the charge - that the NEC prohibits the use of the EGC as part of the GEC connections. That leaves us with the necessity of running another ditch, just to connect the electrodes.

That's why I connected these different assertions to this example of the mobile home .... to highlight the absurdity of the concept. I can hardly wait for the HI forums to discover this "error" in every home with a detached garage, every pedestal installation, etc.

 

[renosteinke]

First off, the HUD standards / UL listing on a mobile home leads me to infer that the home itself is in compliance with the NEC, and that it ought not be any challenge to install it in a code-compliant manner.

Now, let's look at what you must do to hook up a ground rod to a mobile home. It's pretty straightforward - bang in a rod, run a continuous wire to the ground buss in the trailer's panel, and you're done. There are only two problems with that ...

The first is- how will you run the wire? The mobile home is already assembled; there's no access panel for this purpose. Nor is the trailer constructed with a 'tail' for attaching to the ground rod. The 'continuous' requirement of the GEC pretty much precludes simply attaching it to the trailer frame with a beam clamp (and I'm a bit leery of trying to cadweld there!)

The second is the assertion -made in another thread at this forum- that the EGC for the feeder cannot be part of the GEC network. That would mean that we also have to run the GEC to the pedestal as well.

Of course, it's quite possible that I've lived my life in blissfull ignorance, blind to the plain meaning of the never-changing code. That's why I extended the invitation to the audience to produce pictures of just ONE trailer grounded in this manner: multiple ground rods, GEC connections between all, etc. If that's not possible, then we have to conclude that the various code provisions being cited are either being misued, or are simply wrong in themselves.

 

[don_resqcapt19]

Don, I agree with you, and that's certainly what I've been doing ... letting the EGC of the feeder provide the connection to the grounding network of the main building.

Yet, this very forum, quite recently, said differently. I believe it was Bob (Iwire) who led the charge - that the NEC prohibits the use of the EGC as part of the GEC connections. That leaves us with the necessity of running another ditch, just to connect the electrodes.

That's why I connected these different assertions to this example of the mobile home .... to highlight the absurdity of the concept. I can hardly wait for the HI forums to discover this "error" in every home with a detached garage, every pedestal installation, etc.

I agree that the EGC cannot be used as a GEC, but that is the case with second structures. The connection between the two grounding electrode systems is not a grounding electrode conductor.