Hi, This is the sernario. Mobile/manufactured home park. New doublewide on slab. Unattached garage will have the service on it to serve the home and going to use the rebar in footing for the grounding electrode. Question does the rebar in the slab that has the home on it need to be bonded to the grounding electrode system?
UFER ground question
- Thread starter elecmen
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- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
The NEC does not say anything about that. IMO, use the ufer and don't worry about the rebar in the slab
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
Unless there are special rules for mobile homes, it would seem to me that the trailer is a separate structure and thus requires a GES. The code requires all qualifying grounding electrodes at a structure to be bonded together, and then to the EGC feeding the structure.
IMO, the rebar in the slab is not a GE. However, if the slab has a footer that has rebar in it, the rebar in the footer probably is a GE.
romex jockey
Senior Member
- Location
- Vermont
- Occupation
- electrician
There is no lower Ze than a UFer
However, the MBJ may be displaced up to 30' from it here
Lightning liking straighter paths essentially makes it ineffective
~RJ~
However, the MBJ may be displaced up to 30' from it here
Lightning liking straighter paths essentially makes it ineffective
~RJ~
petersonra
Senior Member
- Location
- Northern illinois
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- Semi-retired engineer
if lightning hits a CEE it will likely explode.
Cow
Senior Member
- Location
- Eastern Oregon
- Occupation
- Electrician
I don't install grounding electrodes for trailer houses at the trailer house. I only install them at the service.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
david
Senior Member
- Location
- Pennsylvania
550.16 Grounding.
(A) Grounded Conductor.
(B) Equipment Grounding Means.
(C) Bonding of Non?Current-Carrying Metal Parts.
I would see article 550 as not requiring an addition grounding electrode at the manufactured/ mobile home. The grounding electrode is bonded at the service equipment. If the service equipment is adjacent to the manufactured home the bonding would be at that location
petersonra
Senior Member
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- Northern illinois
- Occupation
- Semi-retired engineer
I don't see anything there that provides any exception to anything in article 250.
david
Senior Member
- Location
- Pennsylvania
550.32 (A) would require an disconnect within sight and not more than 30 ft from the manufactured home
david
Senior Member
- Location
- Pennsylvania
550.32(A) directs you to the disconnect that had the required bonding
(C) Bonding of Non?Current-Carrying Metal Parts.
(1) Exposed Non?Current-Carrying Metal Parts. All exposed non?current-carrying metal parts that may become energized shall be effectively bonded to the grounding terminal or enclosure of the distribution panelboard. A bonding conductor shall be connected between the distribution panelboard and accessible terminal on the chassis.
(2) Grounding Terminals. Grounding terminals shall be of the solderless type and listed as pressure-terminal connectors recognized for the wire size used. The bonding conductor shall be solid or stranded, insulated or bare, and shall be 8 AWG copper minimum, or equivalent. The bonding conductor shall be routed so as not to be exposed to physical damage.
Mobile home when supplied by a feeder are only required an insulated equipment ground connection from the distribution panel to the disconnect required to have compliance with 250.32
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
What does any of this have to do with the requirement to have a GES at each structure?
david
Senior Member
- Location
- Pennsylvania
I?m am not sure where you are seeing a reference from article 550 to article 250 or 250.32 requiring a grounding electrode connected to the mobile home equipment grounding system at the mobile home distribution panel When supplied by a feeder.
How are you getting from article 550 to article 250?
Article 550 specifically indicates the connection to the grounding electrode at the outside adjacent service rated disconnect. I do see a requirement for the GEC to the service equipment when installed on or in a manufactured home.
The requirement has more restrictive verbiage requiring the grounding electrode conductor a means of routing it outside the manufactured home. It seems to be implying that the grounding electrode conductor needs some insurance not to be in contact with the structure after making connection to the service equipment grounded conductor.
Granted there is no given reason for the routing language but when you couple that with the insulated equipment ground, I tend to conclude they are trying to avoid either stray voltages or some other cause that would elevate a voltage on the grounding system in manufactured home.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
Nothing in article 550 says it eliminates any requirements found in article 250.
article 250 requires a GES at a separate structure supplied by a feeder.
the trailer is clearly a separate structure.
I don't have an issue with the requirement to feed separate N and G wires into the trailer, and make the N-G bond at the outside service point. That is consistent with the current rules in article 250.
article 250 requires a GES at a separate structure supplied by a feeder.
the trailer is clearly a separate structure.
I don't have an issue with the requirement to feed separate N and G wires into the trailer, and make the N-G bond at the outside service point. That is consistent with the current rules in article 250.
david
Senior Member
- Location
- Pennsylvania
elecmen;1657125 Question does the rebar in the slab that has the home on it need to be bonded to the grounding electrode system?[/QUOTE said:
david
Senior Member
- Location
- Pennsylvania
Well I do not see it that way I see it as NFPA 70 article 550 and NFPA 501 govern the installation standards for mobile and manufactured homes.
I see it that article 550 specifically details where the grounding electrode conductor is to be bonded to the supply system s grounded conductor.
I see article 550 detailing that the insulated equipment ground in the feeder assembly (power supply0 as making that connection to the manufactured homes equipment grounding system and the supply (service) grounded conductor.
We seemly are not going to agree and I?m not going to go into a long debate on the subject.
david
Senior Member
- Location
- Pennsylvania
I will add for your consideration that article 250 says structure, article 550 is a mobile structure and that makes the difference. Article 550 has specific rules for a structure that is designed to be mobile.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
And I will add for your consideration that defining something as a mobile structure does not mean that it is not also a structure.
In other places where a section replaces or overrides basic sectiond, that relationship is spelled out in the more specific section(s).
- Location
- Massachusetts
Mobile or permanent it is a separate structure and article 250 applies as does article 550.
- Location
- Massachusetts
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