Well, for starters, you'll need to install a disconnecting means within 30 feet of the mobile home 550.32(A). At this disconnect, you will need 2 more ground rods in addition to the two at the meter pole.
Unless you are dealing with a really old mobile home, the neutrals & equipment grounds will already be separated & waitng for that 4 wire feeder.
I don't believe that URD will be in compliance. You must pick a conductor or cable from table 310.3 Try looking into USE-2 , most brands that I've seen are also listed as RHW.
Take a look at all of Article 550, especially section III. Tom
Few things are harder to put up with than the annoyance of a good example.
In this installation, there is NO pole within 30 feet and NONE of the other mobile homes in this park have a second pole next to the mobile home except for an overhead drops. This goes from the meterbase and ocpd on the POCO pole to a main breaker inside the trailer 100 feet away.
You said URD was not an acceptable choice of conductors. What is URD for if not for underground feeder?
USE is the almost the same thing is it not? I am sorry to disagree but I think you are mistaken. This is an UNDERGROUND SERVICE LATERAL.
Why is a mobile home any different than any other dwelling?
The answer to your question is contained in the definition of a mobile home that is found in the US NEC.
"Mobile Home. A factory-assembled structure or structures transportable in one or more sections that is built on a permanent chassis and designed to be used as a dwelling without a permanent foundation where connected to the required utilities and that includes the plumbing, heating, air-conditioning, and electric systems contained therein." Copyright 2002 The National Fire Protection Association
It is the permanent chassis that makes these buildings unique because that chassis serves as an equipotential plane under the mobile home. The equipotential plane will be at ground potential if the unit is properly installed. If any fault occurs in the wiring of a mobile home the chassis is likely to distribute that stray voltage and current over the entire shell and many of the fixtures and appliances of the mobile home. That characteristic is unique among dwelling places to mobile homes. The consequences of a wiring fault being so much more likely to result in electrical shock to persons living in or visiting a mobile home justifies the additional precautions required by the US NEC. -- Tom H
"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
Hi, Does art 550 cover mobile homes OUTSIDE of a MOBILE HOME PARK?
I am not sure if I m reading that right or not but it almost seems like the article is only for mobile homes in a mobile home park or the manufacture of the home itself. There are several references to mobile home parks in this article.
The installations I am looking at do not appear to meet the requirement for a disconnect within 30 ft of the exterior wall.
This would not make a lot of sense either.
Why have a meterbase with a disconnect on a pole and then run over to another disconnect on a pole within 30 feet of the mobile home then run to the main panel within the mobile home?
That three OCPD'S on a single service!
Whats the big deal anyway? I have seen less on a circuit in a nuclear plant!
I've always rejected mobile home feeders that were done with URD cable unless it was also marked "USE" and/or "RHW." URD does not show up in table 310.13 Also, the few times I ran across URD, I don't recall seeing the mark of a NRTL on it. I've also looked through the UL wire marking guide and "URD" does not appear there, so I don't believe UL even evaluates this type of cable.
As far as the 30 foot requirement is concerned, it is not a requirement of the POCO it is an NEC requirement, though some POCO's do write it into their requirements. If you choose not to do this installation to the miniimum requirements of the NEC, that's your choice, but you will be creating some liabilty for yourself.
Article 550 covers mobile homes in or outside of a mobile home park, so you should comply with the rules regardless of location.
As far as your question about running over to a second disconnect, there would be no need for this if the first disconnect was within the required 30 foot measurement. This rule has been in the section on mobile homes since at least 1978 (my oldest code book) and I've been told that it goes back to the original article when it first appeared (early 1960's).
Don't be sorry about disagreeing, thats what these forums are for.
Few things are harder to put up with than the annoyance of a good example.
Hi, The URD cable I see IS UL Listed and it is STAMPED RHW. Please see the following: http://www.centriccable.com/prod_MobHomeFeeder.asp . This page shows that the cable is specifically designed for mobile home feeders. It says that the cable is RHW and that it is UL listed too. I am not clear as to where the RHW requirement is coming from. 550.33 says that the conductors must meet 310.12 and if i read it correctly the exception allows no gec between the service and the disconnect.
I understand that all i need is a unfused disconnect at the second pole.
The main problem I see is that it will be the ONLY setup like this in the WHOLE neighborhood.
I always meet the code so I will have to install this second pole.
The POCO will not allow the meterbase on any pole other than their pole out on the curb.
USE cable is no problem for me, I just happen to see the URD at the supply house and it is labeled MOBILE HOME FEEDER.
I just want to avoid any extra expense.
I may contact the state electrical inspector to see what he will say about the installation and what is going on with the rest of the mobile home on this street.
There is NOT a SINGLE mobile home out of about 100 that I looked through that had this arrangement. There is no local inspection here so I think the POCO basically set the presedence by requiring the meterbase on their pole. This saves them money on feeders.
Maybe I should go with an OH drop? from their pole to my pole within 30 feet?
The POCO acted like they had no idea about the requirement. They said that everything from the point of attachment down was the owners responsibility which I understand.
I do not go around looking at what other people have done to determine my installations but I do notice things and that got me to wondering.
Thanks for the helpful replies.
[This message has been edited by mustangelectric (edited 12-03-2004).]
Hi, I spoke to the POCO and they said they were NOT aware of this requirement. I also sent an e-mail to my state inspector asking for some clarification.
The POCO said that they would get up with the engineers and look into it.
They called me back and said they would be making some changes to their requirements.
They said that they now wanted a 3" conduit ran from their pole underground to a PEDESTAL within the 30 feet of the exterior wall of the mobile home.
I have seen these pedestals but have never installed one.
Aren't they just buried in the ground?
I wonder how this happens? Don't the poco have to use the NEC for its requirements? I know they are exempt from it on their own property and equipment but they should also be required to follow the code. There is a case for the fact that they are only responsible for so much but on the other hand they should not be connecting to installations that do not meet art 550.
What type of liability do they have and what about the recent installations up there that do not meet 550?
Should the state be inspecting areas that do not have a building dept? I am not trying to stir the pot.
Thanks for all the replies. I am real glad I asked about this.
(B) Not Covered. This Code does not cover the following:
(5)Installations under the exclusive control of an electric utility where such installations
a.Consist of service drops or service laterals, and associated metering, or
b.Are located in legally established easements, rights-of-way, or by other agreements either designated by or recognized by public service commissions, utility commissions, or other regulatory agencies having jurisdiction for such installations, or
c.Are on property owned or leased by the electric utility for the purpose of communications, metering, generation, control, transformation, transmission, or distribution of electric energy.
Bob Badger Construction & Maintenance Electrician Massachusetts