wire through back of detached nema 3 panel

Status
Not open for further replies.
A

A.W. Davis

Member
Location
California
This may be a silly question but I cant seem to find any referances in my NEC book on the subject.

I am just wondering if you can pass a sheethed THHN subfeed wire through the back of an exterior surface mounted NemaType3 panel as long as you have a short length of conduit passing through where it penetrates the exterior of the house to protect the circuit?

Same rules and questions apply for an exterior surface mounted A.C. disco. box?

My thought would be as long as the circuit passes through the conduit as it passes through the exterior part of the house and brought into the panel and is secured just before entering the conduit then it will be okay, true, yes/no?
 
Last edited:
THHN has to be in a raceway regardless of the location.

Also most THHN is also THWN which can be used in wet locations....in a raceway.
 
Okay so must the raceway i.e. conduit run the whole length to the subpanel?

I have seen many many times where this is not the case with A.C. disc. boxes that have a sleeved conduit where the wire passes through the back of the panel and exterior of the house and continues as a sheethed 10-3 wire to the s.p.
 
Last edited:
A.W. Davis said:
Okay so must the raceway i.e. conduit run the whole length to the subpanel?
Click to expand...

Yes if your using THHN/THWN.

I have seen many many times where this is not the case with A.C. disc. boxes that have a sleeved conduit where the wire passes through the back of the panel and exterior of the house and continues as a sheethed 10-3 wire to the s.p.
Click to expand...

That is not THHN/THWN, that is a cable assembly of NM, MC, AC etc and does not require a raceway.
 
iwire said:
Yes if your using THHN/THWN.



That is not THHN/THWN, that is a cable assembly of NM, MC, AC etc and does not require a raceway.
Click to expand...

My mistake I meant NM in my original post...I dont know why I was thinking thhn...brain fart
 
A.W. it is not proper forum etiquette to go back an edit posts after they have been replied to, it makes the replies not make sense and the whole thread gets garbled.

Roger
 
It's usually easier to just post seperately your corrections instead of editing them into the original post. (It confuses the rest of us!)

My only concern with the short pvc sleeve would be securing it as it enters the panel.
 
JohnJ0906 said:
My only concern with the short pvc sleeve would be securing it as it enters the panel.
Click to expand...

Yeah that was my thought that there would essentially be no connector at the box preventing the wire from movement.

If the wire was stapled to a framing member just before entering through the conduit sleeve (roughly 4" away) I am wondering if that is up to NEC standards?
 
Would it be possible to mount a box, like a 4"square opposite the panel so the conduit terminates to the box? The romex could enter the box through a connecter, then through the conduit to the panel.

Your orininal idea might be OK, but I'm not sure.
 
JohnJ0906 said:
Would it be possible to mount a box, like a 4"square opposite the panel so the conduit terminates to the box? The romex could enter the box through a connecter, then through the conduit to the panel.

Your orininal idea might be OK, but I'm not sure.
Click to expand...

That was my thought as well...the only downside which isnt a big deal is having the blank four sqaure cover plate on the interior of the house.
 
Hasn`t this very subject been beat to death on numerous occasions ????? I believe the majority will agree that there is no real problem with entering the BACK of an exterior enclosure.Some prefer to duct seal the connector.

Since the majority almost 99.9 %, of the homes we do here are block and stucco.I install the disconnect on rough in.That way they sit nice and flush. The stucco guys do what they do and the disconnect IMO is now slightly embedded in the wall.So they are not in a wet location.IE NM is suitable.
 
Lets not forget the bending raduis for the conductors in Table 312.6(A)&(B).



For instance, lets say one is installing a 200 amp service.


The meter pan is on the outside wall. Directly inside and opposite is the panel/disconnect. Table 310.6 (dwelling) permits size 4/0 Al. As the conductors enter the inside panel/disconnect, what is the minimum bending radius required? (which of the 2 tables does one refer to?)
 
Pierre C Belarge said:
Lets not forget the bending raduis for the conductors in Table 312.6(A)&(B).



For instance, lets say one is installing a 200 amp service.


The meter pan is on the outside wall. Directly inside and opposite is the panel/disconnect. Table 310.6 (dwelling) permits size 4/0 Al. As the conductors enter the inside panel/disconnect, what is the minimum bending radius required?
Click to expand...

I did not forget but that section simply does not limit the bending radius of a conductor.

That section requires we leave a certain amount of space for the conductors but I do not have to use all that space.

I could take my Greenlee Hydraulic conductor bender and put right angle 90 degree turns in those 4/0s.
 
The conduit or cable entries should be made below any termination piont on the exterior disco to maintain its rating.
 
allenwayne said:
Hasn`t this very subject been beat to death on numerous occasions ????? I believe the majority will agree that there is no real problem with entering the BACK of an exterior enclosure.Some prefer to duct seal the connector.

Since the majority almost 99.9 %, of the homes we do here are block and stucco.I install the disconnect on rough in.That way they sit nice and flush. The stucco guys do what they do and the disconnect IMO is now slightly embedded in the wall.So they are not in a wet location.IE NM is suitable.
Click to expand...

I havent been on here long enough to encounter such discussions...I did a quick search and found nothing so thats why I posted my question.

Isnt it code for those Nema-3 panels to have the required 1/4" of spacing on the backside? If you burry a surface mounted box in the stucco, will that fly with inspectors, I would think an inspector would not want to see that.
 
A.W. I have been here for quite awhile and I don't know what Allen is talking about.

It may have come up before but obviously not nearly as much as some issues or it would be in the FAQ's

Roger
 
A.W. Davis said:
I am just wondering if you can pass a (Edited from thhn to nm cable) subfeed wire through the back of an exterior surface mounted NemaType3 panel as long as you have a short length of conduit passing through where it penetrates the exterior of the house to protect the circuit?
Click to expand...
Is this really any different then entering the top of a panel with a piece of conduit and sleeving the nm cable inside it. I know article 312.5(C) mentions entering the top of an enclosure but I cannot see the difference as long as the conduit is bushed as per article 300.14(C).
I know I am going to get grief on this one.
 
iwire said:
I did not forget but that section simply does not limit the bending radius of a conductor.

That section requires we leave a certain amount of space for the conductors but I do not have to use all that space.

I could take my Greenlee Hydraulic conductor bender and put right angle 90 degree turns in those 4/0s.
Click to expand...




I mispoke when I said the "bending radius" of conductors. It is not technically the bending radius of the conductor, although ultimately it will directly affect the bending radius of the conductors.

As per my question above, Tables 312.6(A)&(B) will restrict where one tries to enter an enclosure, such as the back, side, top or bottom of the enclosure. This is due to the "space" (width, depth) necessary to bend the conductor without degredating the insulation of the conductor.

What is the answer to the question I posted in my previous post?
 
Status
Not open for further replies.
Top