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Old 03-16-2010, 07:07 PM   #16
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I have also never installed grounding electrodes for a mobile. I don't consider a mobile home a manufactured home. A mod is a manufactured home.
I think the NEC agrees since Art 500 is titled "Mobile Homes, Manufactured Homes, and Mobile Home Parks".
Personally I do not consider a mobile home a structure.

Also, 550.32 states that grounding at the disconnecting means shall be in accordance with 250.32. Nothing is said about the panel in the trailer.
All we find about the trailer itself is about bonding.
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Old 03-16-2010, 07:24 PM   #17
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Ground rods have never been required at the mobile home for the same reason that the service equipment is not to be mounted in or on the mobile home ---------- because it is mobile.

The whole point behind this is when a trailer house (mobile home ) is removed from the trailer park or any other place, which is done quite frequently in some areas, the grounding electrode system stays intact. When the next trailer is moved in, there is no need to worry about driving another ground rod or hooking up a GEC.

It is basically connected as a temporary structure, which it is designed to be, it's called a mobile home for a reason, because it is supposed to be mobile (moved).

It's about safety, which is all the NEC is really about, or supposed to be anyways.
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Old 03-16-2010, 07:44 PM   #18
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Unfortunately the NEC is seemingly vague about the ground rod issue at the distribution panel board for a mobile home. However you need to ask yourself why do they require service equipment to not be attached to a mobile home? Silk answered this for me.

HUD CFR 3280 sets the standards for mobile homes which are by HUD definition easily transportable housing. The weak argument you talk about is the reason behind the SE and ground rods not being attached to the fixed wiring of the mobile home.

They are not farm services but nice try .... Farm services are special services however and amend the previous chapters.

The reason I brought up 550.16 is to point out grounding (not the ges) is through the power cord over the egc to the service equipment (550.32) where it first mentions anything about a ground rod. You will notice there is no mention of a grounding electrode system for the mobile home itself once grounding {550.16(A) thru (C)} has been met. You only need to comply with 550.32(A) at that point as for a ground rod and ges for the mobile home. And notice 550.16 is titled Grounding and no mention of grounding electrode conductor being part of grounding the mobile home electrical system... only grounding for human safety not equipment.

The reason I brought up 250.32 not applying is because of 90.3. You will notice that it says chapters 5,6 and 7 are special occupancies or equipment and modify chapters 1,2,3 and 4. Chapter 5 makes no mention of a ges for the mobile home structure only requirement is at the service equipmnt not attached to the mobile home.

At service equipment (not attached) is the only place a GES is required by 550.32(A) amending 250.32 IMO. Otherwise I would think that it would mention grounding in accordance with 250.32 is required.

I don't know how else to argue this as the NEC doesn't come out and
say flatly that a ground rod is not required at the mobile home. It does however become very clear about the service equipment for the moible home needs a ground rod.

You will also find if you look on a search engine that a ground rod for the mobile home is never required by any local jurisdiction that I can think of or find. I'll be glad to provide some examples if you wish.

Did I do any better......

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Old 03-16-2010, 09:32 PM   #19
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[=Speedy Petey;415607]I have also never installed grounding electrodes for a mobile. I don't consider a mobile home a manufactured home. A mod is a manufactured home.
a manufactured home (per the NEC) is a home built on a permanent frame intended to be set on a permanent foundation.

A modular home does not have a permanent frame, only a temp one for transportation.


Quote:
I think the NEC agrees since Art 500 is titled "Mobile Homes, Manufactured Homes, and Mobile Home Parks".
Personally I do not consider a mobile home a structure.
then what is a structure to you? How about we use the NEC definition:

that which is built or constructed


Quote:
Also, 550.32 states that grounding at the disconnecting means shall be in accordance with 250.32. Nothing is said about the panel in the trailer.
All we find about the trailer itself is about bonding.[
that's right. I already said that but as the home is a structure, it also must abide by 250.32
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Old 03-16-2010, 09:43 PM   #20
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Ground rods have never been required at the mobile home for the same reason that the service equipment is not to be mounted in or on the mobile home ---------- because it is mobile.
I think you need to read what the definition (in the code 550.2) of a manufactured home versus a mobile home. If there is a permanent foundation, it is a manufactured home. From what I have found so far, if the unit has the axles and tongue removed, is mounted an just about any type of concrete support, is tied down and has skirting installed, it is on a permanent foundation. That means just about every home of this type that I and most likely you have worked on is considered to be (per the NEC as a manufactured home.
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Old 03-16-2010, 09:49 PM   #21
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Quote:
Stubbie;415639]

You will also find if you look on a search engine that a ground rod for the mobile home is never required by any local jurisdiction that I can think of or find. I'll be glad to provide some examples if you wish.

sure but since most areas I know of use the NEC, it will be up to local interpretation


and for fun:


Quote:
In June of 1976, the United States Congress passed the National Manufactured Housing Construction and Safety Act (42 U.S.C.), which assured that all homes were built to tough national standards. In 1980, Congress approved changing the term 'Mobile Home' to 'Manufactured Home'.
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Old 03-16-2010, 09:52 PM   #22
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Originally Posted by Stubbie View Post

The reason I brought up 250.32 not applying is because of 90.3. You will notice that it says chapters 5,6 and 7 are special occupancies or equipment and modify chapters 1,2,3 and 4. Chapter 5 makes no mention of a ges for the mobile home structure only requirement is at the service equipmnt not attached to the mobile home.
:
that's right, they modify, not replace. Therefore, if there is a different method employed in 5 6 and 7, that is used over 1 2 3 and 4. If there is no alteration in 5 6 and 7, that would mean that what is in 1 2 3 and 4 is still applicable.
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Old 03-16-2010, 10:48 PM   #23
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=Silk;415618]Ground rods have never been required at the mobile home for the same reason that the service equipment is not to be mounted in or on the mobile home ---------- because it is mobile.
Um, you might want to do a bit of reading. The service is allowed to be mounted on a manufacturered home and if you will read what the code defines as a manufacturered home, it most likely will be what you and I are speaking about, not a mobile home.

Quote:
The whole point behind this is when a trailer house (mobile home ) is removed from the trailer park or any other place, which is done quite frequently in some areas, the grounding electrode system stays intact. When the next trailer is moved in, there is no need to worry about driving another ground rod or hooking up a GEC.
Oh, so removing the skirting, attaching the axles and wheels and tongue and cutting loose the tiedowns, removing the siding from the ends of the home and then reinstalling all of that is less trouble than driving a couple ground rods?

I don't know how many homes you have near you but I have proabably 500 within 5 miles of me and thousands within 35 miles of me. Once they are placed in a park, they rarely leave.



Quote:
It's about safety, which is all the NEC is really about, or supposed to be anyways.
and that is why you place a ground rod at an accessory building and it would serve the same purpose for a manufactured home.
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Old 03-16-2010, 11:18 PM   #24
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I think the issue here is going to boil down to whether we have a mobile home /manufactured home as defined in art. 550 or manufactured home as defined in art. 550.32(B) In art. 550 the NEC says for the purposes of this article mobile homes include manufactured homes unless otherwise indicated.

So lets pursue when these two type dwellings suddenly become considered differently.. Maybe then we can reach a consensus cause I certainly understand NAPs steadfastness based on NEC language. Who knows I might even change my mind before this is done....

Ok..so where are the indicated differences? First if the service equipment is not installed on the home or in the home it is a mobile home/manufactured home regardless of whether it is on a permanent foundation or not and regardless of its construction method as per HUD cfr 3280 ..the NEC considers them the same.

A distinction occurs in 550.32(B) where it specifically calls out whether or not the mobile home is treated the same as a manufactured home. Remember by construction and design they are different. Where it has service equipment mounted on or inside the home along with 7 requirements. All those being met then if the home is a manufactured home by construction then a ges system is installed as per article 250 or manufacturers instructions. So just being anchored down or on permanent foundation does not make a mobile home a manufactured home falling under article 250 where a grounding electrode system is installed in accordance with article 250.32.
Point being that all 7 requirements along with the service equipment being mounted on the home or in the home and the home must be a manufactured home not a mobile home as determined by HUD cfr 3280 before 250.32 would apply.

So my opinion is that if the service equipment is not on or in the home it is a mobile home as in 550.32(A) utilizing a cord and plug power hookup and no ground rod required. Whether you want to call it a manufactured home or mobile home at that point is irrelevant since code considers them them the same under those guidelines. But the minute you meet all the provisions of 550.32(B) you have separated the common considerstion of the two types of dwellings and are dealing with a manufactured home not a mobile home. And grounding requirements are now allowed to follow art. 250.


If you have a mobile home defined by HUD CFR 3280 you have a mobile home and if that mobile home sits on a permanent foundation or not it is still a mobile home as it is designed to not be on a permanent foundation. An achoring system or sitting on blocks does not make the mobile home a manufactured home under 550.32(B)and therefore is magically treated differently. What I am saying here is if you have a mobile home it cannot fall under 550.32(B) as it is not a manufactured home. It is a 550.32(A) service type dwelling no ground rod required.

If you have detached service equipment with a 4 wire feeder cord or otherwise to the mobile home or manufactured home it does not fall under 250.32. However as said earlier a manufactured home (not a mobile home) due to construction differences can be separated from a mobile home by 550.32(B) and grounding for a ges changes at that point.

EDIT: IMO There would be no reason for 550.32(B) to call out a difference in grounding requirements if 250.32 was understood to apply from the beginning. As I said earlier there is one other situation where 250.32 is allowed and that is if the service equipment is located farther than the 30 feet set out in 550.32(A) at which point you are required to have a service disconnect within 30 feet of the mobile home. You would set a structure ..ie..pole etc.. and mount a disconnect between the mobile home/manufactured home and service equipment on that pole. You would then provide a ground rod at the disconnect location in accordance with 250.32 but there is not a ground rod at the mobile home/manufactured home in this case either. This arrangement is very common in mobile home parks where it is wanted for the service equipment to be centralized.

Thats my story and I'm sticking to it.....
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Old 03-16-2010, 11:26 PM   #25
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The more you type (Nap not Stubbie, I'm a slow typer), the dumber this gets.

550.2 differentiates between mobile and manufactured homes as to what they were designed as. Not as to whether you put skirting or haybales around it, not whether you take the tires and axles of or leave them on. If you want to call all mobile homes as manufactured homes then don't argue with us about it, put a recommendation into the RFPA and tell them you don't believe in the Easter Bunny, the Tooth Fairy or in the Mythical Mobile Home.

Until that time as you can make all the mobile homes disappear with a wave of your magic wand, I think I will believe my own eyes when I pass by a trailer park.

The point is that the Grounding Electrode System shall be independant of the mobile home.

One last point. A mobile home is not a structure. It falls under Chapter 5 and is considered a Special Occupancy.

The rules for chapters 1 thru 4 are general. Chapters 5 thru 8 are specialized. The rules in 5 thru 8 supercede the general rules for 1-4. If you are going to use a codebook the first thing you must do is learn how it is organized.
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Old 03-16-2010, 11:54 PM   #26
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all one has to do to distinguish between a manufactured home and a mobile home is read the definition in 550.2

no other considerations are needed to determine if it is a mobile or manufactured home for NEC purposes.

the only real difference I see between a mobile home and a manufactured home is:

a manufactured home is at least 320 sq ft or if less, the manufacturer files a certification required by the regulatory agency (whatever that means)

a manuf home can be designed to be installed on a permanent foundation or not. A mobile home is not intended to be installed on a permanent foundation.

Now, with that said, remember what I had stated comprises a permanent foundation: pads and piers (minimum) for support, skirting, home attached to foundation, axles and wheels removed.

so, how many homes you thought were mobile homes had such a foundation and were over 320 sq ft?





Once you determine what the home is classified as, then you can apply the various rules. You do not use the rules to determine the classification.



Quote:
So my opinion is that if the service equipment is not on or in the home it is a mobile home as in 550.32(A) utilizing a cord and plug power hookup and no ground rod required.
there is no requirement the service be installed in or on a manufactured home. Code says it is allowed, not required.
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Old 03-17-2010, 12:11 AM   #27
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The rules for chapters 1 thru 4 are general. Chapters 5 thru 8 are specialized. The rules in 5 thru 8 supercede the general rules for 1-4. If you are going to use a codebook the first thing you must do is learn how it is organized.
right, supersede but if there is no rule in contrast to the common rules of 1-4, they still apply.


as such, we must follow the common rules in the earlier chapters and modify them or alter them if there is a contradicting rule in 5 through 7. There is nothing contradicting putting a ground rod at a manufactured home.


Quote:
The point is that the Grounding Electrode System shall be independant of the mobile home.
and that would be what section?

maybe the section of silk is making it up because it does not say that anywhere?

Quote:
550.2 differentiates between mobile and manufactured homes as to what they were designed as.
you need to read it again. a manufactured home can have the same basic design specs as a mobile home or a manuf home can also be designed to be set on a permanent foundation. Size appears to be the most obvious determining factor.

Quote:
A mobile home is not a structure. It falls under Chapter 5 and is considered a Special Occupancy.
Now who is being a dullard? Based on that statement of yours, an airplane hanger, a commercial garage, motor fuel dispensing facilities, bulk storage plants and even health care facilities are not structures either as they are all also in chapter 5 as special occupancies.

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Old 03-17-2010, 02:30 AM   #28
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You know this has been a rather interesting journey and I must say it has caused me to blow a lot of accumulated dust off my brain as far as how the NEC requires mobile/manufactured homes to be treated for grounding electrodes.

I'm finding it very difficult to expose the code language that would emphatically deny the used of 250.32. I only know that we don't install ground rods at mobile homes permanent foundation or not and we do not install service equipment on or in mobile homes. Manufactured homes are actually a little rare around my parts at least I think they are....

I also agree with nap after careful consideration that the biggest difference is size from what I'm reading as we take this excercise into it's final hours or posts I should say. I also think one needs to be careful with mixing modular homes with manufactured homes. The actually differences in construction between a mobile home and manufactured home --are or not that great and appearances a very similar ...it's primarily size and overall dimensions as nap said. However none the less they are different and labeled as to there intended design.

Unfortunately I cannot find that arrow through the heart that says in plain english that a mobile home or manufactured home does not follow 250.32 for the dwelling structure unless 550.32(B) is proven. At least I can't pull it out of article 550 language. I think its there but one has to assume that there are 550.32(A) mobile/manufactured homes and 550.32(B) manufactured homes ... mobile homes not included.

So the challenge for me is proving how to treat a mobile home / manufactured home that doesn't fall under 550.32(B). But again I find it strange that 550.32(B) is necessary if I am to follow 250.32 unless indicated otherwise in article 550. I am inclined to feel that the intent of the cmp is to follow 550.32(A) unless I am dealing with a 550.32(B) manufactured home and article 250 does not apply otherwise.

For what it's worth the attached is a paste of a mobile home requirement for overhead electrical installation and there is no ground rod at the structure. The mobile home/manufactured home is set on blocks in this case.
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Old 03-17-2010, 07:17 AM   #29
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Quote:
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right, supersede but if there is no rule in contrast to the common rules of 1-4, they still apply.

But is has been superceded by 550.16 which says "grounding shall be connected through the Equipment Grounding Conductor to the adjacent service equipment"


as such, we must follow the common rules in the earlier chapters and modify them or alter them if there is a contradicting rule in 5 through 7. There is nothing contradicting putting a ground rod at a manufactured home.

Again 550.16



Now who is being a dullard? Based on that statement of yours, an airplane hanger, a commercial garage, motor fuel dispensing facilities, bulk storage plants and even health care facilities are not structures either as they are all also in chapter 5 as special occupancies.

You still are. And yes they all are special occupancies and not just a normal structure, otherwise they wouldn't have their own section.

How much easier can this stuff be? It's all spelled out for and still your confused. Maybe the NEC should make a special picture book --- with Big Print for a few people out there.
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Old 03-17-2010, 09:06 AM   #30
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Quote:
=Silk;415884]You still are. And yes they all are special occupancies and not just a normal structure, otherwise they wouldn't have their own section.
Oh, so now they aren't a normal structure. Very different than your last claim:

Quote:
A mobile home is not a structure. It falls under Chapter 5 and is considered a Special Occupancy.


so, since you at least admit you were wrong, I guess it's ok.

a structure is still a structure.

by the way, the section is

"special occupancies"

not special structures. That means how the structure is used is the point.

maybe you need a pair of glasses and a dictionary.

read:

occupancy


structure

read them aloud to yourself 100 times each. then look up the definition of each. then maybe you will start to grasp the difference.



Quote:
How much easier can this stuff be? It's all spelled out for and still your confused. Maybe the NEC should make a special picture book --- with Big Print for a few people out there.
at least I know the difference between a structure and an occupancy.


by the way, there are probably several thousand manufactured homes in parks and on private land within 35 miles of me (and several thousand more setting at the factories they are made. yes, I live near Elkhart Indiana where millions of the dang things have been made.) and yes, we do put ground rods at a manufactured home that is set on a permanent foundation. I know of no installations that are not on a permanent foundation as it is not legally allowed to leave a manufactured home as a temporary installation in the area. (Michigan or Indiana)

the problem with you silk is you are simply wrong. You have been working on manufactured homes all this time and were totally ignorant of the fact. I doubt anybody has installed a mobile home park anywhere in your area in at least 30 years, if not longer. The last mobile home parks in may area were made in the '60's.


and stubbie;

I told you earlier the difference between a modular home and a manufactured home.

a manufactured home is built on a steel frame that stays in place regardless of how it is installed. It is an integral part of the structure. Manufactured homes receive a HUD certification


a modular home is basically a stick built home, built in a factory in sections and assembled on site. There is no permanent steel frame. There is a steel frame used only for transporting the sections to the home site. The frames are returned to the manufacturer to be used to transport other mod home sections. Modular homes must be built utilizing the building codes of the area the home is to be installed.

wikipedia actually explains the difference fairly well:

Quote:
Modular homes vs. mobile homes
Differences include the building codes that govern the construction, types of material used and how they are appraised by banks for lending purposes. The codes that govern the construction of modular homes are the exact same codes that govern the construction of any site constructed home. In the United States, all modular homes are constructed according the International Building Code (IBC), IRC, BOCA or the code that has been adopted by the local jurisdiction.
Mobile homes (manufactured homes) are constructed according to the HUD Code and are generally considered lesser quality. The materials are the same as site constructed homes. Wood frame floors, walls and roof is the most typical. Some modulars even included brick or stone exteriors, granite counters and steeply pitched roofs. All modulars are designed to sit on a perimeter foundation or basement. Mobile homes are constructed with a steel chassis that is integral to the integrity of the floor system. Mobile homes often require special lenders. Most companies have standard plans. However, all modular buildings can be custom built to a clients specifications. Today's designs include multi-story units, multi-family units and entire apartment complexes. The negative stereotype commonly associated with mobile homes and has prompted some manufacturers to start using the term Off-Site Construction.

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