Mobile Home

[GG]

Re: Mobile Home

Well after reading what has ben written here Im going to plant a ground rod at the mobile home and one at the service disconnect. There sure seem to be alot of bricks being thrown and gun fire in posts lately. So Im taking cover.

[ August 14, 2005, 01:49 PM: Message edited by: GG ]

 

[dillon3c]

Re: Mobile Home

Originally posted by taylorp:


Mobile Homes are covered in article 550 of the NEC, which is Chapter 5. Chapter 5 modifies or supplements Chapters 1-4.

If you will carefully read 550.32, the mobile home service shall not be mounted in or on the mobile home. Mobile home services are not separate structures as far as the code is concerned. A mobile home service mounted on a pole or pedestal up to 30 feet away is still part of the mobile home.

*This gentleman here answered-(nailed)-it in my opinion for me. And this morning, was my personal thought thinking out-loud(*as I denoted, in my opinion)..I had to get my own mind behind it also, before I threw my hat in.

*Just like Bob's thinking of generator in Chapter 4. His opinion, and I can respect that. Even though I believe it has no bearing on this subject in Chapter 5, I offered no rebuttal.*I respect iwire's opinion to disagree.(& u too jim)

*I even searched the archives,when this thread first posted,and haven't found anything definitive yet, so had reserved my thought.

*I came to my personal decision this morning,so I'm on the record now..(for what its worth)-->Weighing in..

Noted:I don't wire mobile home services,I'm of the commercial,industrial.And I have certainly have not yet inspected one.

I will be dropping E-Mail to my Chief Inspector,but believe the definitive answer has already been found..

Came back to Edit:When I mention Chapter 4,it was off the top of my head-(445 on the brain)-sorry..

dillon

[ August 14, 2005, 03:24 PM: Message edited by: dillon3c ]

 

[taylorp]

Re: Mobile Home

Gentlemen (and or Ladies):

The proper order is this: Apply Article 550 for the electrical installation of Mobile homes, then refer to Chapters 1-4 as directed in 550.

Some of us are using Chapters 1-4 to wire Mobile homes, then we refer to Article 550.

This logic is backwards. Once you leave Chapters 1-4 the remaining chapters either supplement, modify or are not subject to the requirements of Chapters 1-4 except where the requirements are specifically referenced.

I respect Mr. Badger's (iwire) and Mr. JimWalker's electrical knowledge. There is nothing in the NEC (to my knowledge) to PROHIBIT the additional Grounding Electrode. The question seems to be "Is a grounding electrode and GEC required at the panelboard located within the Mobile Home?"

Article 550.16 tells us how to ground this panelboard within the Mobile home:

. . . The grounding bus shall be grounded 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. Neither the frame of the mobile home nor the frame of any appliance shall be connected to the grounded circuit conductor (neutral) in the mobile home. . . .

This is a classic description of a how to ground a sub-panel located WITHIN the same building or STRUCTURE that the service is located.

Perhaps this subject under discussion needs some serious condsideration and clarification by Code Making Panel #19 for 2008.

Mr. Dillon3c, I would be curious to know what your Chief inspector says. GG, good luck on your installation.

P.S. I enjoy the Code Forum very much and I am always challenged to constantly study the NEC by such distinguished company.

 

[iwire]

Re: Mobile Home

Originally posted by taylorp:
The proper order is this: Apply Article 550 for the electrical installation of Mobile homes, then refer to Chapters 1-4 as directed in 550..

I disagree with your order.

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.........

We must use all the rules of chapters 1 to 4 unless specifically modified in 550.

There is nothing in 550.16 that amends the rules in chapters 1 to 4.

[ August 14, 2005, 04:25 PM: Message edited by: iwire ]

 

[taylorp]

Re: Mobile Home

Mr. Badger:

You say a GE and GEC are REQUIRED for the Mobile home sub-panel per Article 250, and I say they are NOT REQUIRED per Article 550.

Who can settle this difference of opinion except for the Almighty, Code Making Panel #19, or our local AHJ?

Many thanks.

 

[iwire]

Re: Mobile Home

First call me Bob.

Second I just do not see anything in 550 that releases us from the rules of 250.

You say that we have to stay in 550 for an MH unless told to go other places.

How do you size the conductors feeding the MH.

I do not see anything in 550 that tells us to go back to 310.16.

Anyway, we will have to agree to disagree.

 

[jwelectric]

Re: Mobile Home

One thing that I think should be pointed out about these ground rods can be found in 550. The wording is the same in both the 2002 and 2005 cycles. Posted below are these words. After reading them please explain what you think they mean.

550.33 Feeder. (A) Exception: Where a feeder is installed between service equipment and a disconnecting means as covered in 550.32(A), it shall be permitted to omit the equipment grounding conductor where the grounded circuit conductor is grounded at the disconnecting means as required in 250.32(B).

Now I am not making a statement about weather the ground rod would or would not be required at two different places.

I am asking would it be okay to install only three conductors between the service and inside panel if I did install the ground rod at the trailer.

 

[dillon3c]

Re: Mobile Home

Originally posted by jwelectric:


I am asking would it be okay to install only three conductors between the service and inside panel if I did install the ground rod at the trailer.
[/QB]

I was hopeing mike,you hadn't turned in yet.

My answer is no,you couldn't install a three wire feeder to a " Mobile Home " anyway,regardless of the driven electrode,or not.

Hang with me,and gimmie your take.

550.2~Mobile Home:
For the purpose of this Code and unless otherwise indicated,the term mobile home includes manufactured homes.

550.11(a)Disconnecting Means
-the neutral bar termination of the grounded conductors shall be insulated in accordance with 550.16(a)

550.16 Grounding
Grounding of both electrical and non-electrical metal parts in a "Mobile Home" shall be through connection to a grounding bus in the "Mobile Home" distribution panelboard.The grounding buss shall be grounded 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.

*Neither the frame of the "Mobile Home" nor the frame of any appliance shall be connected to the grounded circuit conductor (Neutral) in the "Mobile Home".

*Where the distribution-panel board is the service equipment as permitted by 550.32(B)-(*Manufactured Home) the neutral conductors and the equipment grounding bus shall be connected.

550.16(a) Grounded (Neutral) Conductor
(1)Insulated
*shall be insulated from the equipment enclosure (*the Mobile Home)..Where the distribution panel board is service equipment as permitted by 550.32(b) the (*Manufactured Home)-neutral conductor and the equipment grounding conductor shall be connected.

*This totaly disregards any notion, of useing a three-wire supply cord, feeder to the inside interior of the "Mobile Home",and being in compliance..

*The exception, in 550.33 feeder,refering to 550.32(a)-My opinion:
*the disconnecting means shall be located in sight and not more than 30' from the exterior wall of the "Mobile Home" it serves.If beyond this requirement as in: located elsewhere on the premises the requirement of not exceeding 30' from the exterior wall, still must be met.

Thus the exception of 550.33 which a feeder to the second outside disconnecting means,meeting the requirement of the exception, and able to use the three-wire feeder between the two disconnecting means 250.32(b)(2)(outside the exterior wall)of the "Mobile Home"..

*driven electrode required, at this second location.

Gimmie your opinion, in the morning Mike..

I'm e-mailing Danny,on the separate structure(250.32) aspect,of the "Mobile Home" driven electrode.

dillon

[ August 15, 2005, 08:09 AM: Message edited by: dillon3c ]

 

[jimwalker]

Re: Mobile Home

"If you will carefully read 550.32, the mobile home service shall not be mounted in or on the mobile home. Mobile home services are not separate structures as far as the code is concerned. A mobile home service mounted on a pole or pedestal up to 30 feet away is still part of the mobile home. "

If it's still part of the mobile home then how can you mount the service to it? "the mobile home service shall not be mounted in or on the mobile home."

Only thing i can say here is mobiles without a rod either shared or seperate seem to be the normal but violate nec as a seperate structure.
Doing something wrong a million times and still passing does not change anything.Electrons will not know they are going to a mobile under 550 or a detached garage.How can the mobile be safe but not the ground ? But then i never figured out why a garage with only 1 circuit does not need a ground rod

And what happens when we add a room to this mobile ? Is it still a mobile ? At what point is a mobile no longer a mobile ?

 

[jwelectric]

Re: Mobile Home

Dillon

Sorry about the bed time last night. I am just getting up this morning and having the first cup of coffee.

As you have stated above and pointed out sections to support your statements a mobile home must have a four wire feeder from it?s service disconnect.

Originally posted by dillonc3
*This totaly disregards any notion, of useing a three-wire supply cord, feeder to the inside interior of the "Mobile Home",and being in compliance..

*The exception, in 550.33 feeder,refering to 550.32(a)-My opinion:
*the disconnecting means shall be located in sight and not more than 30' from the exterior wall of the "Mobile Home" it serves.If beyond this requirement as in: located elsewhere on the premises the requirement of not exceeding 30' from the exterior wall, still must be met.

Thus the exception of 550.33 which a feeder to the second outside disconnecting means,meeting the requirement of the exception, and able to use the three-wire feeder between the two disconnecting means 250.32(2)(outside the exterior wall)of the "Mobile Home"..

These statements are correct as it concerns the service of a mobile home as outlined be the 2005 cycle of the NEC.
550.32 clearly states how the service equipment is to be installed on a mobile home.

Originally posted by iwire
Second I just do not see anything in 550 that releases us from the rules of 250.

You say that we have to stay in 550 for an MH unless told to go other places.

How do you size the conductors feeding the MH

Bob I cover this in my Level I Standard Inspector class. I would love to have you attend one. The last half of a Level I will be taught at RCC this weekend. You are welcome to attend.
To answer your questions, first we size the service conductors as outlined in 550.18 and part (C) gives permission to use 220.82.

We ground the mobile home as outlined in 550.10 (B)&(C) for the use of a cord and (I) if using an overhead feeder. 550.11 tells about the grounding bar in the distribution panel located inside the home. 550.16 gives the criteria for the equipment grounding conductor and the grounded (neutral) conductor and 550.32 mandates how the service is to be installed.

Originally posted by taylorp
The proper order is this: Apply Article 550 for the electrical installation of Mobile homes, then refer to Chapters 1-4 as directed in 550.

This is a true statement and is the correct way to install the service and feeders for a mobile home.

As to the matter of driving a second ground rod at the mobile home, it is clear that 550 mandates that the service be outside of the home and the home be supplied by feeders. Should this mandate the use of an additional rod it would have been pointed out in 550.
Yes 550 is a stand alone article and supercedes all other articles as pointed out in;

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.

550 gives the criteria for the grounding and bonding and no mention of the second ground rod when told that the service is to be separate from the home. Therefore no second rod is required.


edited to get the quote codes right

[ August 15, 2005, 08:23 AM: Message edited by: jwelectric ]

 

[OneWay]

Re: Mobile Home

Either way you decide to go with this job, remember that some parts of Florida are more difficult to establish a good ground. We all know that 25ohms or less is good. We all know that to get 25ohms or less it would be an involved installation. I would suggest that you drive a rod at the MH and bond to a ground bonding conductor which originates at the service disconnect where another ground rod should be driven. In no way saying your certain to get 25ohms or less, yet more to insure that the MH frame and sub-parts are grounded.

 

[iwire]

Re: Mobile Home

Mike please try to make your posts more concise, like one issue per post, it is very difficult to respond to a post that is all over the book.

In this case I will stick to which Article comes first.

Originally posted by jwelectric:

Originally posted by taylorp
The proper order is this: Apply Article 550 for the electrical installation of Mobile homes, then refer to Chapters 1-4 as directed in 550.

This is a true statement and is the correct way to install the service and feeders for a mobile home.

As to the matter of driving a second ground rod at the mobile home, it is clear that 550 mandates that the service be outside of the home and the home be supplied by feeders. Should this mandate the use of an additional rod it would have been pointed out in 550.
Yes 550 is a stand alone article and supercedes all other articles as pointed out in

Nope, you got it wrong.

Bob

[ August 16, 2005, 07:05 PM: Message edited by: iwire ]

 

[jwelectric]

Re: Mobile Home

Yes I did get it a little wrong with the phrase that 550 was a stand alone article. The way that I should have worded it was that 550 modifies 250 and the grounding rules outlined there as pointed out in the introduction the NEC.

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.

Those sections that I have pointed out in my last post makes it very clear how the grounding and bonding is to be done in a mobile home. The service disconnecting means although 30 feet away is still part of the mobile home and will not require a second ground rod to be installed as outlined in 250.32 (B).

 

[jwelectric]

Re: Mobile Home

Originally posted by iwire:
Mike please try to make your posts more concise, like one issue per post, it is very difficult to respond to a post that is all over the book.

 

[iwire]

Re: Mobile Home

You still are not getting it right my friend

Originally posted by jwelectric:
Yes I did get it a little wrong with the phrase that 550 was a stand alone article. The way that I should have worded it was that 550 modifies 250 and the grounding rules outlined there as pointed out in the introduction the NEC.

Nothing in 250 is modified unless 550 specifically says so.

The sections you have pointed out have nothing to do with structures or electrodes.

Don't bother posting 90.3 again I know what it says as a matter of fact I posted it a while back in this thread.

Please be so kind to point out to us what section in 550 modifies 250.32?

The service disconnecting means although 30 feet away is still part of the mobile home

And just where is that tidbit of information located in the NEC?

 

[iwire]

Re: Mobile Home

Originally posted by jwelectric:
I also answered your question of how to size the feeders for a mobile home and I didn?t leave 550 to do that. I do believe that I answered all questions out of 550 therefore those questions about the grounding, feeders and the sizing of the feeders all are amended by 550 and supercede those of 250 and 220.

Never mind I give up.

 

[jimwalker]

Re: Mobile Home

My earlier solution is only way to fix this.Stop at big orange and buy a 2x4 :roll:

 

[jwelectric]

Re: Mobile Home

Originally posted by OneWay:
I would suggest that you drive a rod at the MH and bond to a ground bonding conductor which originates at the service disconnect where another ground rod should be driven. In no way saying your certain to get 25ohms or less, yet more to insure that the MH frame and sub-parts are grounded.

I am not sure that I understand what you are saying here, could you explain a little better.

Are you saying to drive a rod at the mobile home and tie the frame to it? Or tie it to the grounded (neutral) conductor and the rod at the service?

I don?t fully understand what you are saying here.

I really don?t understand why anyone would drive a second rod at the mobile home for to start with. I have read article 550 more times that some in here are years old and in more cycles of the code than years that some in here have been working at public work and have never found anything that would lead me to believe that a rod would be required for the mobile home. Where is this coming from?

 

[jwelectric]

Re: Mobile Home

Originally posted by iwire:
You still are not getting it right my friend

The service disconnecting means although 30 feet away is still part of the mobile home

And just where is that tidbit of information located in the NEC?

 

[jwelectric]

Re: Mobile Home

Mobile Home Accessory Building or Structure. Any awning, cabana, ramada, storage cabinet, carport, fence, windbreak, or porch established for the use of the occupant of the mobile home on a mobile home lot.

I don't see service, do you?