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Mobile Homes and ground rods

Our discussions with 2 separate NFPA staff on 2 separate occasions resulted in the same interpretation. Grounding electrode system required for the subfeed of mobile homes since they are a separate structure.
 
jar546 said:
Our discussions with 2 separate NFPA staff on 2 separate occasions resulted in the same interpretation. Grounding electrode system required for the subfeed of mobile homes since they are a separate structure.
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I have no problem with that. Ironically enough Mr. Sargent is quite respected in the electrical industry and believes otherwise. In many circles, Section 550.16 will provide for all grounding and bonding needed and as long as the EGC is properly sized and provided then I could say what advantage does the additional electrodes play at the mobile structure? Considering we are speaking in regards to issues with transient voltages and lighting mind you. We only need to venture into Section 250.34(B) to understand why vehicle mounted generators do not require a GES when all conditions are met to maybe understand the question...Will adding the additional electrodes at the mobile structure ( which is not installed on a permanent foundation ) benefit the safeguarding of that structure. I guess that is to be decided by the local AHJ at the time of inspection I guess.

Understanding that if we installed a panel on the outside of a building in accordance with allowed practices of Section 230.70(A)(1) knowing that the service is associated with the given structure...would that change our view any? but i am probably digressing too much and to be honest I have seen it go both ways and by many high profile educators (Mr. Sargent included) so opinions will vary and one is just as important as the other. I guess i reflect back on what the definition of a structure is; That which is built or constructed. While I will construct the pole and panel location for the service disconnect/equipment outside and within 30' of the mobile home....the mobile home I did not build or construct, it is mobile with wheels and no permanent foundation....knowing that I run a EGC between them giving them equal potential as possible due to proper bonding techniques...I guess you could go either way and sleep well at night....lightning does not care....it's a proximity thing.

Just some thought on the subject...sorry for rambling...I'm New !
 
This is a Cut and Paste from a jurisdiction in Natrona County, WY that is distributed to contractors and homeowners that are wiring mobile homes:

Grounding: All services shall be grounded by two 5/8” x 8’ copper coated ground rods.

Galvanized ground rods are not permitted due to soil conditions.

A minimum distance of 6’ shall be

maintained between ground rods. Eight to ten feet is preferred.

They must feed by one continuous wire. The first rod can be

close to the service pole. The grounding electrode conductor

from the service panel to the ground rods shall be no smaller

than #6 copper (water pipe clamps can not be used on ground

rods). The equipment grounding conductor from the service

panel to the home shall be insulated (size of equipment ground

depends on size of home service).

So as you can see....it is done differently in many areas of the country and at the end of the day the NFPA says " The CODE is purely advisory as far as the NFPA is concerned."
 
lol...the only reason I would question if Natrona County, WY is a good representation of compliance is the fact they make this statement "They must feed by one continuous wire" when in fact nothing in the code says that. The GEC shall be continuous to the electrode which is the first ground rod...the connection from the first rod to the second is purely a bonding jumper and is not required to be continuous but I think they are just being a bit over cautious...lol
 
Are there 2 choices?

If the home was set up under 550.32(B) (manufactured home only) requires an electrode to the structure but 550.32(A) (mobile and manufactured homes) does not; the grounding electrode is directed for the service equipment that is located outside of the structure.

Francis
 
I believe where many people go wrong is reading the last line of 550.32(A) when it makes reference to Section 250.32. That reference is for the disconnection means that would be required IF the service equipment is more than 30' from the mobile home. The ground rods would be required at the service equipment location as well as in accordance with Section 250.32 (via 550.32(A)). I read a lot where because Section 250.32 requires a GES at all structures an indeed would be the case as always at the service equipment for the most part. I have spoken to many experts in the industry that I am honored to call friends and nearly all of them say no GES is required at the mobile home itself, but they are required at the service enclosure.

So many are still stuck on Section 250.32 and I understand why they would since the code does not make it crystal clear ( as it always does everything else ) right?...I happen to believe (and you can say i am wrong if you wish...i do not mind as my opinions are what they are...my opinions) that the provision of Section 550.16 governs the grounding and bonding requirements of the mobile home to the service equipment and no additional electrodes are needed at the mobile home. yes, I concede that some will argue that nothing in Article 550 removes the general rule of Article 250, well not cleanly anyway and I concede that some will call this a separate structure and should have a GES. However, I fail to see where it would benefit the mobile structure at all if the EGC is supplied to the mobile home from the service equipment.

The potential of transient voltages caused by lightning or other outside factors are relevant to the service enclosure, establishing a connection to earth for reference and stabilization is again relevant to the service enclosure. Nothing in regards to establishing a GES at the mobile home (other than at the service equipment) will benefit the mobile home. Also nothing in the NEC would prohibit the additional ground rods at the mobile home regardless even if you did wish to install them anyway as auxiliary electrodes are permitted by the NEC all the time.

Other than hanging a hat on what some believe in that Section 250.32 requires this GES at the mobile home....I believe Article 550 changes that in my opinion, be it clear or murky I can tell you I would pass the installations either way...install no rods at the mobile home and install a properly sized EGC in accordance with Article 550 and install rods at the service equipment.....or install rods at both and still install a properly size EGC to the mobile home......this really becomes a moot point as both would be acceptable...just as long as we do not connect the grounded conductor to the grounding conductor at this mobile distribution panel.

Sorry for my long winded view....again it is my opinion and many will disagree and call me what they will (on other forums mind you)...it is still an opinion which sides with the head engineer at the NFPA...how ironic is that.
 
Mobile Homes and ground rods

Lol...update...i still have not taken the legal portion of the CBO as i kinda had a job change. However, i plan on taking it in the next few weeks.
 
PaulAbernathy said:
Yep....90.4 says we make the call.
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As does 104.1 of the IBC and IRC.

PaulAbernathy said:
Lol...update...i still have not taken the legal portion of the CBO as i kinda had a job change. However, i plan on taking it in the next few weeks.
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Good luck.
 
= = =

PaulAbernathy,

Welcome to The Building Codes Forum, and "best of

luck" on the CBO Legal / Mgt. test! :cool:

+ + +
 
Florida requires the ground rod in the jurisdictions I have worked in. It is somewhat redundant tho since there will be up to a dozen anchors in the ground too, strapped to the frame and over the top.

I would also look at the labeling on the trailer. Some I have installed say you need an electrode, right on the ampacity tag by the SE.

That makes it a 110.3(B) if nothing else.
 
I'm glad this was resurrected because there was not a total agreement between inspectors and both sides presented great cases.

Can we continue?
 
I don't believe there is a question as to whether or not the mobile home is a structure. The issue is when the service pole is a few feet from the trailer as opposed to 30 feet. IMO, you could use the rods at the pole for the mobile home but the mobile home must have a gec. Now the question becomes how far away can the pole be before the home needs it's own set of electrodes. Not sure this can be answered very easily.

I don't usually wire trailers but if I did I would probably drive new rods unless the pole was a few feet from the home.
 
I have had them so close to the mobile home that they used the same rods as the main disconnect next to the mobile home. 2 rods, 2 different GECs and 4 acorns....LOL
 
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