mobile home & ground rods

[jwelectric]

Mobile homes and manufactured homes are two separate animals and have separate requirements in their construction requirements.
Article 550 has all the information needed to install a wiring system to it without ever looking anywhere else in the code book except those sections referred to by 550.

There is no requirement for the distribution panel in a mobile home to be rated as service equipment as outlined in 550.11. There is no need to install grounding electrodes as outlined in 550.16 and 550.33.

But it is okay for the members of this forum to play around with this as everyone needs something to do or die of boredom.

P.S. Will this be the 1000 post thread?

 

[Smart $]

...
Article 550 has all the information needed to install a wiring system to it without ever looking anywhere else in the code book except those sections referred to by 550.
...

That is not correct. The following is...

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.

 

[hurk27]

Hurk, I really have a problem with your assumptions stated above.

How can you question the usefulness of a rod at the trailer when every other separate structure supplied by a feeder requires a GES?

What I am saying is this .......... I have no idea if the rod is useful or not ........ and neither do you if you are honest with yourself.


But if this did have to go to court how could you possibly argue that a GES at mobile home serves no purpose when all other structures require one. What type of magic does a mobile home have to behave differently?

I also surprised at you having a problem with this view, as much as it has been discussed on here, and in quite a few cases even with documentation? If you are holding this view just because the NEC still requires ground rods, then this goes to show how myths can be held onto just because it is still required, and or passed on, one reason something like this should be removed from the NEC in my view.
Also just because there is a requirement in the NEC does not say it is a scientific fact as we have seen over the years of the changes made when it was proved that something wasn't right, if this was not so, many of the code changes would never be made.

So here is a break down of the myths of a 8' ground rod supposed to do:

Protect a building and its electrical system and its occupants from the effects of lightning.
Here is a post Bryan made back in 2006 on the publish result of a test done that shows very little of the lightning current even followed the path through the rod (which there was 3 of them) to Earth:
http://forums.mikeholt.com/showthread.php?t=77454
The link in the thread to the published paper is dead but can be found here:
http://www.lightning.ece.ufl.edu/PDF/00997942.pdf
It shows that less then 20% of the energy of the triggered strike followed the path to Earth through the rod(s)

As for touch/step potential, stray current/voltage, opening of OCPD's, or anything else that requires passing current through a ground rod, many of us remember the experiments of Crossman Gary who conducted some live experiments that many of us could see that a ground rod was ineffective in reducing or eliminating this hazard, this thread is located here:
http://forums.mikeholt.com/showthread.php?t=116358

As for voltage spike/surges/transients, I cant believe people still think they want to return to Earth, a ground rod does nothing to lower the impact of a surge that is generated usually line to line or line to neutral, it wants to return to source not Earth, even a lightning strike ahead of the utility transformer will be a line to line surge on the house side of the transformer, the transformer isolate the current and it is no longer seeking to return to Earth, this surge would have or should have followed the MGN to the electrode system that is placed every 1/4 mile on the primary system, but once it has crossed a transformer it is no longer reference to Earth because of the isolating effect of a transformer, the same reason a GFP does not function across a transformer.

As for static build up, well if the line was miles long and didn't have other impedances that connected it to Earth like happened in the telegraph lines back when they went to the glass knob insulators, I would agree that they can accomplish this function, but when we have a multi-grounded system that has electrode in every part of the system all connected together, then this need is not there.

I don't want to take this thread sideways any farther but just wanted to answer this post.

Now back to the regular scheduled program

 

[jwelectric]

That is not correct. The following is...

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.

And then there is this;

550.1 Scope.​

The provisions of this article cover the electrical conductors and equipment installed within or on mobile and manufactured homes, the conductors that connect mobile and manufactured homes to a supply of electricity,and the installation of electrical wiring, luminaires, equipment,and appurtenances related to electrical installationswithin a mobile home park up to the mobile home serviceentrance conductors or, if none, the mobile home service equipment.​

Which is just what it says and is what is said in your quote, It amends and stands alone except where it referrences another section​

 

[david]

Here ya go...

Ok I did some comparisons and I am back
Thanks I was aware of 225.31 and .36 that’s really not what I was looking for though.

But that does show that separate structures in the general requirements need disconnects suitable for service equipment thanks.

So it does show that when a grounding electrode is mandated for seperate structures the disconnect also is required to be suitable for service equipment.

I did not hear anyone dispute the statement that a mobile / manufactured home distribution panel (in contrast to a manufacture home service panel) has no mandate for service rated equipment

So we can at least chisel away at the concept when it comes to grounding, mobile homes are just the same as any other structure

 

[Smart $]

And then there is this;

550.1 Scope.

The provisions of this article cover the electrical conductors and equipment installed within or on mobile and manufactured homes, the conductors that connect mobile and manufactured homes to a supply of electricity,and the installation of electrical wiring, luminaires, equipment,and appurtenances related to electrical installationswithin a mobile home park up to the mobile home serviceentrance conductors or, if none, the mobile home service equipment.​

Which is just what it says and is what is said in your quote, It amends and stands alone except where it referrences another section​

I can see where the article scope can be interpretted as such... but it does not actually say that it amends Chapter 1 through 4 requirements except as specifically referenced. A statement of such is required by the Manual of Style and must read...

xxx.3 Other Articles. Wherever the requirements of other
articles of this Code and Article xxx differ, the requirements
of Article xxx shall apply.

 

[hurk27]

I was doing some reading in 3280.804(k) which The disconnecting means shall be listed for use as service equipment, but this is for where the home is set up from the manufacture to have the service mounted in or on the home.

I did see a code that wound be nice if it was in the NEC:
? 3280.814 Painting of wiring.
During painting or staining of the manufactured home, it shall be permitted to paint metal raceways (except where grounding continuity would be reduced) or the sheath of the nonmetallic cable. Some arrangement, however, shall be made so that no paint shall be applied to the individual wires, as the color coding may be obliterated by the paint.

I hate trying to scrap off paint to try to see what the wire colors are:rant:

I thought the NEC said something about this, but I couldn't find it.

Anyone who doesnt have a copy of CFR 24 3280.80 can down load a copy here: http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&tpl=/ecfrbrowse/Title24/24cfr3280_main_02.tpl

Or just click here to directly to the electrical provisions:
http://ecfr.gpoaccess.gov/cgi/t/tex...gn=div6&view=text&node=24:5.1.4.1.1.9&idno=24

High light the text right click then copy, open MS word or simular and paste it into word or a PDF if you have the version that can make documents, and name it what it is, and save it and you now have a copy on your computer.

 

[david]

Ok I am going to ask a question and please do not take this thread into a debate about swimming pools

Please not in my example am going to note a detached garage feed from a existing feeder from a single family dwelling

The garage Is existing and is completely code compliant. It has two ground rods connected to the service rated distribution panel

The garage is closes to the swimming pool i need to run a feeder to pool equipment I want to determine if that feeder can be run from the garage or do I have to run it from the service in the dwelling.
The garage supply is 240/120 volts

I need a feeder I am not interested in supplying the pool with branch circuits

(2) Separate Buildings. A feeder to a separate building or structure shall be permitted to supply swimming pool equipment branch circuits, or feeders supplying swimming pool equipment branch circuits, if the grounding arrangements in the separate building meet the requirements in 250.32(B). Where installed in other than existing feeders covered in 680.25(A), Exception, a separate equipment grounding conductor shall be an insulated conductor.

The reference to 250.32 (B) tells me to look at the feeder how is it connected if it is a four wire feeder and connected correctly I can run my feeder to the swimming pool equipment.

If it is not connected correctly it does not meet the requirements of 250.32 (B) I cannot supply my swimming pool from this panel in the garage

If on the other hand I walk up to the existing garage and it is a three wire URD feeder in PVC it doe not meet the requirements in
250.32 (B)
I cannot supply my swimming pool equipment with a feeder from this garage.

When I get back I am going to contrast this to the feeder requirements
In 547.9 (C) in an attempt to illustrate the difference in referencing 250.32(B) in contrast to referencing 250.32

I believe the difference is deliberate and means two different things

 

[iwire]

I also surprised at you having a problem with this view, as much as it has been discussed on here, and in quite a few cases even with documentation? If you are holding this view just because the NEC still requires ground rods, then this goes to show how myths can be held onto just because it is still required, and or passed on, one reason something like this should be removed from the NEC in my view.

Hurk you missed my point entirely.

The usefulness of a GES is not what we are talking about, we are talking about what it required. If you want to eliminate GESs feel free to take up that battle but that is altogether a separate issue.

My point was simply this, how could you argue a mobile home is different than all other separate structures?

 

[jwelectric]

I can see where the article scope can be interpretted as such... but it does not actually say that it amends Chapter 1 through 4 requirements except as specifically referenced. A statement of such is required by the Manual of Style and must read...


​

No it doesn't say that< "this article amends the rest of the code" but it says what it says. It says that this article is what mandates the connection to an electrical supply period case closed.

550.1 Scope. The provisions of this article cover the electrical conductors and equipment installed within or on mobile and manufactured homes, the conductors that connect mobile and manufactured homes to a supply of electricity, and the installation of electrical wiring, luminaires, equipment, and appurtenances related to electrical installations within a mobile home park up to the mobile home service entrance conductors or, if none, the mobile home service equipment.

I don't see nowhere that says but we must follow anything else, do you.

 

[iwire]

I don't see nowhere that says but we must follow anything else, do you.

Interesting, so we can just ignore all code requirements contained in Chapters 1-4. Cool!:lol::lol::happyno:

 

[don_resqcapt19]

...
I don't see nowhere that says but we must follow anything else, do you.

What about 90.3?

... Chapters 1 through 4 apply except as amended by Chapters 5, 6, and 7 for the particular conditions. ...

 

[david]

What about 90.3?

547.1 Scope.
The provisions of this article shall apply to the following agricultural buildings or that part of a building or adjacent areas of similar or like nature as specified in 547.1(A) and (B).
I don't know yet how strong i feel on this position of 90.3 verses the spacific scoping of
550.1 But as i compare other articles scoping statements to 550.1 the scoping for mobile homes seem to give a lot of weight to article 550. 547 not so far reaching.

Does anyone know of a circumstance that the article missed a referance back to the general requirements that would change how the code is applied to mobile home

 

[david]

550.33 and Exception: Revised for correlation with revisions to 250.32(B) and new exception to 250.32(B).

If the revisions to 550.33 where not made to correlate with 250.32(B)

Would you be free to install a three wire feeder between the service equipment or would you have to go to the general requirements and install a four wire feeder betweeen the service and the disconnect?

This may be to far off point so i am going to stop with that

 

[iwire]

547.1 Scope.
The provisions of this article shall apply to the following agricultural buildings or that part of a building or adjacent areas of similar or like nature as specified in 547.1(A) and (B).
I don't know yet how strong i feel on this position of 90.3 verses the spacific scoping of
550.1 But as i compare other articles scoping statements to 550.1 the scoping for mobile homes seem to give a lot of weight to article 550. 547 not so far reaching.

If your position is the scope of 550 is what modifies Chapters 1-4 you are essentially saying nothing in Chapter 1-4 applies at all. From conductor sizing to wiring methods.

 

[david]

If your position is the scope of 550 is what modifies Chapters 1-4 you are essentially saying nothing in Chapter 1-4 applies at all. From conductor sizing to wiring methods.

II am saying it is not an un reasonable position to say that the scoping of the article seems to say it controls everything associated with a mobile home up to the supply . So if the article is taking control over everything . then every thing critical not spelled out in this article should have a reference to the general requirements

 

[iwire]

I am saying it is not an unreasonable position to say that the scoping of the article seems to say it controls everything associated with a mobile home up to the supply . So if the article is taking control over everything . then every thing critical not spelled out in this article should have a reference to the general requirements

OK, given that, what size conductors do I use for this service?

 

[jwelectric]

Interesting, so we can just ignore all code requirements contained in Chapters 1-4. Cool!:lol::lol::happyno:

Yes this is what i am saying except where referenced like in 550.15.
What is being discussed here is the grounding electrode system. I would inject into the conversation section 550.4(C)

 

[david]

OK, given that, what size conductors do I use for this service?

550.1 Scope.
The provisions of this article cover the electrical conductors and equipment installed within or on mobile and manufactured homes, the conductors that connect mobile and manufactured homes to a supply of electricity ????.


Feeder Assembly. The overhead or under-chassis feeder conductors, including the grounding conductor, together with the necessary fittings and equipment or a power-supply cord listed for mobile home use, designed for the purpose of delivering energy from the source of electrical supply to the distribution panelboard within the mobile home.

First of lets determine if the scoping covers the service

 

[iwire]

550.1 Scope.
The provisions of this article cover the electrical conductors and equipment installed within or on mobile and manufactured homes, the conductors that connect mobile and manufactured homes to a supply of electricity ????.


Feeder Assembly. The overhead or under-chassis feeder conductors, including the grounding conductor, together with the necessary fittings and equipment or a power-supply cord listed for mobile home use, designed for the purpose of delivering energy from the source of electrical supply to the distribution panelboard within the mobile home.

First of lets determine if the scoping covers the service

You lost me again........:?

I thought I asked a simple question, if as you stated Article 550 covers all things relating to the supply of power to a mobile home how do I know what size conductors to use?