GEC to mobile frame

Status
Not open for further replies.
J

james blake

Member
Location
Colorado
Hi guys. We are running a 120/208 feeder to a mobile classroom that has a 100A main panel on the inside of the mobile. We are going to install a new 200A main panel on an exterior wall of the mobile and either sub-feed the old panel or convert it to a junction box. The bond to the frame of the mobile was, of course, made at the existing panel. Since we will be installing a new main panel, should the bond to the frame be made at the new panel?
 
james blake said:
Hi guys. We are running a 120/208 feeder to a mobile classroom that has a 100A main panel on the inside of the mobile. We are going to install a new 200A main panel on an exterior wall of the mobile and either sub-feed the old panel or convert it to a junction box. The bond to the frame of the mobile was, of course, made at the existing panel. Since we will be installing a new main panel, should the bond to the frame be made at the new panel?
Click to expand...

Wouldn't your boond be a different size?
 
james blake said:
... Since we will be installing a new main panel, should the bond to the frame be made at the new panel?
Click to expand...
Yes... and likely a larger size as mentioned.... but...

550.11 infers a distribution panelboard, disconnecting means combination must be accessible from the inside.

Additionally, you must also meet the requirement for the service equipment under 550.32. If the service equipment is located elsewhere on the premises, you must still have a disconnecting means per either (A) or (B)... but since this is unlikely a manufactured home, it has to be under (A). See 550.4(A) which is regarding "Mobile Home Not Intended as a Dwelling Unit." There is no such section regarding a manufactured home is the reason why I say meet 550.32(A), and the disconnecting means cannot be located in or on the structure but must be located in sight and not more than 30ft from the exterior.
 
Smart $ said:
Additionally, you must also meet the requirement for the service equipment under 550.32. If the service equipment is located elsewhere on the premises, you must still have a disconnecting means per either (A) or (B)... but since this is unlikely a manufactured home, it has to be under (A). See 550.4(A) which is regarding "Mobile Home Not Intended as a Dwelling Unit." There is no such section regarding a manufactured home is the reason why I say meet 550.32(A), and the disconnecting means cannot be located in or on the structure but must be located in sight and not more than 30ft from the exterior.
Click to expand...

Smart, This is interesting. I wouldn't even have thought of applying Art. 550.

My question is, if a mobile home is designed to be a dwelling, it would have to have provisions for living, sleeping, cooking and sanitation, then would a mobile structure that didn't have provisions for cooking or sanitation still fall under 550.4(A)?

In other words, a mobile home (with provisions for cooking/sanitation) could be used as a job office, or dorm, etc.

But a mobile classroom building (without provisions for cooking/sanitation) wouldn't be a "mobile home," would it?
 
Thanks for the for feed back so far guys. I'll give you guys a little more information on our mobile sites. Usually at new schools a mobile pad site is installed by the contractor. At existing schools, we build them. Our pad sites consist of a transformer, distribution panel, and a low voltage enclosure. The DP is usually 400 to 800 amps depending on the size of the mobile site. From the pad site we run pvc to a disconnect mounted on a pedestal near the mobile. From the disconnect we pipe to the mobile panel. Most of our mobiles are manufactured with a 200A main panel with a disconnect, installed on the exterior of the mobile. We do have some very old mobiles that have the panels installed on the inside. Due to the frequent moving of the mobiles, we have been installing new main panels on the outside of the older mobiles to help expedite the moving and hook-up process.
 
david luchini said:
Smart, This is interesting. I wouldn't even have thought of applying Art. 550.

My question is, if a mobile home is designed to be a dwelling, it would have to have provisions for living, sleeping, cooking and sanitation, then would a mobile structure that didn't have provisions for cooking or sanitation still fall under 550.4(A)?

In other words, a mobile home (with provisions for cooking/sanitation) could be used as a job office, or dorm, etc.

But a mobile classroom building (without provisions for cooking/sanitation) wouldn't be a "mobile home," would it?
Click to expand...
In my private and professional opinion, anything that looks like a mobile home on the outside is a mobile home. It don't matter what is or what one does on the other side of the exterior doors. ;) (other than electrical matters, that is)

Article 550.4(A) essentially says the same thing in a more politically correct manner :D
 
Last edited:
james blake said:
Thanks for the for feed back so far guys. I'll give you guys a little more information on our mobile sites. Usually at new schools a mobile pad site is installed by the contractor. At existing schools, we build them. Our pad sites consist of a transformer, distribution panel, and a low voltage enclosure. The DP is usually 400 to 800 amps depending on the size of the mobile site. From the pad site we run pvc to a disconnect mounted on a pedestal near the mobile. From the disconnect we pipe to the mobile panel. Most of our mobiles are manufactured with a 200A main panel with a disconnect, installed on the exterior of the mobile. We do have some very old mobiles that have the panels installed on the inside. Due to the frequent moving of the mobiles, we have been installing new main panels on the outside of the older mobiles to help expedite the moving and hook-up process.
Click to expand...
This all sounds good until you get to the DP on the outside...
550.11 Disconnecting Means and Branch-Circuit Protective
Equipment. … (text omitted for brevity …

(A) Disconnecting Means. A single disconnecting means
shall be provided in each mobile home … (text omitted for brevity) …
The distribution panelboard shall be located in an accessible
location but shall not be located in a bathroom or a
clothes closet. A clear working space at least 750 mm
(30 in.) wide and 750 mm (30 in.) in front of the distribution
panelboard shall be provided. This space shall extend
from the floor to the top of the distribution panelboard.

(B) Branch-Circuit Protective Equipment. Branch circuit
distribution equipment shall be installed in each mobile
home and shall include overcurrent protection for each
branch circuit consisting of either circuit breakers or fuses.
… (text omitted for brevity) …
Click to expand...
The two red highlights makes it appear quite concise, while the blue highlights connotates the disconnecting means is to be inside, yet such is tacitly expressed (read, in other words: a bit vague or obscure, but then again, implicit).
 
The "in" word makes sense. We have been getting the brand new mobiles with the main panel on the outside for years. They all get inspected and nothing is ever said. Is the manufacturer or the inspector missing this?
 
I see one of the problems with 550 is that it defines both mobile and manufactured homes, but mostly talks about mobile ones. I'll guess that the buildings in question are manufactured not mobile. If they're anything like the one's I've seen, each section is 12' wide. clearly fits in the definition of manufactured.

Also, look at 550.10 Power Supply- "(A) Feeder. The power supply to the mobile home shall be a feeder assembly consisting of not more than one listed 50-ampere mobile home power-supply cord..." If it comes with a 200a panel, the maker doesn't think it's mobile either.

Also, 550.32(B) "The manufactured home service equipment shall be permitted to be installed in or on a manufactured home, provided that all of the following conditions are met:"

Clear as mud, IMHO,
 
Something that might help clarify the Mobile Home/Manufactured Home quandry. In June of 1976, HUD started regulating the manufacturing of Mobile Homes under the "Manufactured Housing Safety Standard". As of that date, they were called Manufactured Homes, not Mobile Homes. Typically, Mobile Homes were built to be cord and plug connected with a 50 amp service. Maufactured Homes were then built to be connected t a power supply with a permanently installed feeder.

Not to be confused with Modular Homes which are built in a factory, but must comply with a Model Building Code that requires an on-site third party inspector to verify compliance. Hope this helps.
 
Once again, thanks for the input guys. I also too found that every "mobile" home built after July 1976 was classified as a "manufactured" home. That is probably why they were built with the panels installed on the exterior wall and the AHJs never had a problem.
 
I think we need to look in 545 for the requirments of a mobile classroom

545.3Manufactured Building. Any building that is of closed construction and is made or assembled in manufacturing facilities on or off the building site for installation, or for assembly and installation on the building site, other than manufactured homes, mobile homes, park trailers, or recreational vehicles.
Click to expand...

and see 545.7
 
zbang said:
I see one of the problems with 550 is that it defines both mobile and manufactured homes, but mostly talks about mobile ones. I'll guess that the buildings in question are manufactured not mobile. If they're anything like the one's I've seen, each section is 12' wide. clearly fits in the definition of manufactured.

Also, look at 550.10 Power Supply- "(A) Feeder. The power supply to the mobile home shall be a feeder assembly consisting of not more than one listed 50-ampere mobile home power-supply cord..." If it comes with a 200a panel, the maker doesn't think it's mobile either.

Also, 550.32(B) "The manufactured home service equipment shall be permitted to be installed in or on a manufactured home, provided that all of the following conditions are met:"

Clear as mud, IMHO,
Click to expand...
Trying to classify a mobile classroom as a manufactured home is negated in the definition (550.2), which requires, among other requirements, that the structure be "designed to be used as a dwelling". A mobile classroom designed as such does not meet that qualification... so it has to meet mobile home requirements or qualify as an Article 545 manufactured building. That determination is made by other regulatory agencies, not the NEC.
 
As I said, clear as mud.

On the one hand, you have the definition of mobile home ("intended to be used as a dwelling") and manufactured home (wider than 8'). Then there's 550.4(A) Mobile Home Not Intended as a Dwelling Unit for a mobile home ("intended to be used as a dwelling"). It also mentions 120/240v connections but of course, job trailers are often fed from 120/208v. Which brings in 550.4(C) and 550.10(A), which says you can't feed it with more than 50a. If you consider the trailer to be a Manufactured building, it all becomes more sensible.
 
Status
Not open for further replies.
Top