Mobile Homes & PVC to Panel

[augie47]

Some food for thought tonight..........
Wondering how different folks handle the installation of circuits for HVAC condenser units on mobile homes.
A number of the mobile homes I've inspected lately have a factory installed empty PVC into the home panel.
E/Cs have used this to wire the condenser unit. The practice opens a number of questions in my mind.
(a) Since the mobile homes are a pre-wired HUD unit, is it legal to add a circuit to the interior panel ?
(b) If you can add a circuit, would the requirement of 550.20(B) prevent you from wiring the condenser this way.

and a related question:
(c) Can NM be installed under a mobile home if properly supported and following a building surface ?
(d) If NM, UF, or any cable is installed under the mobile home, would the use of the factory stub violate 312.5(C) ?

 

[ceb58]

Some food for thought tonight..........
Wondering how different folks handle the installation of circuits for HVAC condenser units on mobile homes.
A number of the mobile homes I've inspected lately have a factory installed empty PVC into the home panel.
E/Cs have used this to wire the condenser unit. The practice opens a number of questions in my mind.
(a) Since the mobile homes are a pre-wired HUD unit, is it legal to add a circuit to the interior panel ?
(b) If you can add a circuit, would the requirement of 550.20(B) prevent you from wiring the condenser this way.

and a related question:
(c) Can NM be installed under a mobile home if properly supported and following a building surface ?
(d) If NM, UF, or any cable is installed under the mobile home, would the use of the factory stub violate 312.5(C) ?

I think 550.32 D would allow for the connection to a cond. unit. It is for additional elect. equipment out side the MH. connected ether in the MH OR ext. disco.

550.15 H doesn't allow for nm, uf under chassis. It requires RMC or IMC with conductors listed for wet locations

 

[Jim W in Tampa]

Most that i see here run the package unit from the panel on the pole. They usually have a 200 main with feed thru lugs to mobile along with 8 circuits

 

[benaround]

I think 550.32 D would allow for the connection to a cond. unit. It is for additional elect. equipment out side the MH. connected ether in the MH OR ext. disco.

550.15 H doesn't allow for nm, uf under chassis. It requires RMC or IMC with conductors listed for wet locations

Ceb58,

I'll have to disagree on 550.32(D), it allows connection to the MH service equipment or the

local external disconnecting means, both are located outside the MH. The interior panel is a

'sub-panel' supplied by a feeder. MH service equipment is also explained in 550.32(A).

 

[benaround]

Some food for thought tonight..........
Wondering how different folks handle the installation of circuits for HVAC condenser units on mobile homes.
A number of the mobile homes I've inspected lately have a factory installed empty PVC into the home panel.
E/Cs have used this to wire the condenser unit. The practice opens a number of questions in my mind.
(a) Since the mobile homes are a pre-wired HUD unit, is it legal to add a circuit to the interior panel ?
(b) If you can add a circuit, would the requirement of 550.20(B) prevent you from wiring the condenser this way.

and a related question:
(c) Can NM be installed under a mobile home if properly supported and following a building surface ?
(d) If NM, UF, or any cable is installed under the mobile home, would the use of the factory stub violate 312.5(C) ?

Gus,

(a) IMO yes, as long as it does not supply additional outside electrical equipment using a

fixed wiring method.

(b) IMO, 550.20(B) refers to a MH that comes with the branch circuit already provided for

the outside heating, a/c, or both equipment.

(c)As Ceb58 pointed out 550.15(h)

(d) IMO yes, 312.5(c) allows for entry to the 'top' of the enclosure.

 

[pfalcon]

(a) The panel is not pre-wired. The structure is built off-site instead of on-site. Most new MH come with connection points for the condenser units installed off-site. Final wiring is still done on-site. Power goes through the inside panel.

(b) 550.20(B) does not tell you where to get the power from. It only requires an outside disconnecting means and a label. Power can still come from inside the MH. The provision does not have to pre-exist as long as there is space and power available.

(b) 550.32(D) is not a requirement for AC. It is an acknowledement that a MH may not have space in the inside panel. Therefore space must be provided at the outside service. If you use that space from the outside service then you must use fixed wiring methods.

 

[stew]

We run most of our hvac runs for this application from the existing indoor panel which in newer homes have a stub down just below floor level. We us nm for the entire run and penetrate the sidewall into an outdoor box. we then use pvc from that point with thhn to the disco and flex from the disco with thhn to the unit. The nm run under the home is required to be protected. This is accomplished by sleeving the nm where it runs under and across the joists. It is required to be protected only where it emerges from the joist area. If we can get to the stub and attach without too much trouble then we just extend the raceway its full length and use thhn. I disagree with what I think is being posted calling this a wet area. It is no different than running under a stick built house and is in MHO at most a damp area so nm is ok for the app.

 

[augie47]

We run most of our hvac runs for this application from the existing indoor panel which in newer homes have a stub down just below floor level. We us nm for the entire run and penetrate the sidewall into an outdoor box. we then use pvc from that point with thhn to the disco and flex from the disco with thhn to the unit. The nm run under the home is required to be protected. This is accomplished by sleeving the nm where it runs under and across the joists. It is required to be protected only where it emerges from the joist area. If we can get to the stub and attach without too much trouble then we just extend the raceway its full length and use thhn. I disagree with what I think is being posted calling this a wet area. It is no different than running under a stick built house and is in MHO at most a damp area so nm is ok for the app.

Similar installs here are what prompted the question. Local discussion has resulted in the inspectors agreeing that the "factory" PVC stub down, when present, can not be used with NM (or any cable) as it violates 312.5(C){It may be used to connect to other PVC}
As far as the use of NM, the consensus of opinion was that, as you state, this could likely be damp location thus prohibiting NM under 334.12(B).
Although I agree there may be little difference between a conventional and mobile home in this regard, 550.15(H) does seem to lead one to prohibiting NM.
The reason for the post was to see how it is being addressed in different jurisdictions.

 

[stew]

apparently the violation of 312.5(C) is due to not securing? also the 334.12 section d say "excessive" moisture or dampness. Crawl spaces have never been included in this defintiion as far as I know otherwise you would never be able to use nm in that area.Anyway the inspectors in this area (Washington) are a separate group from the regular L&I folks and they accept this type of install all the time. We have also used this type of install in other city juridictions and have had no problems with any corrections of this method.Anyhow its just the way we do it at times and it seems ok.

 

[cowboyjwc]

We have a great way to handle it, we let the state deal with it.:grin:

 

[benaround]

This is the way the story was told to me. A MH can be repo-ed just like an automobile.

When the lender sends someone out to repo the MH, that person should not have to be

faced with disconnecting electrical equipment that has fixed wiring to outside structures

or equipment. This is why 550.32(D) says that this equipment must be connected to the

outside service equipment or the outside disconnecting means. If the additional outside

equipment was connected via cord and plug, the panel inside the MH could serve the

equipment.