NMB to porch light

Status
Not open for further replies.
J

jetlag

Senior Member
Location
Eatonton, Georgia
I read the post on NMB to AC . There was a short pvc outside up to DISC switch. The replies were the NMB must terminate in box before leaving the house and continue on with thwn. My guestion is if NMB runs thru outside wall into back of a surface mounted WP fixture box is the wire considered outside and against code? What if the box is flush mounted, does that make it not outside. I guess we should run NMB to the switch and short piece UF to light?
 
jetlag said:
I read the post on NMB to AC . There was a short pvc outside up to DISC switch. The replies were the NMB must terminate in box before leaving the house and continue on with thwn. My guestion is if NMB runs thru outside wall into back of a surface mounted WP fixture box is the wire considered outside and against code? What if the box is flush mounted, does that make it not outside. I guess we should run NMB to the switch and short piece UF to light?
Click to expand...
Not sure why anyone thinks NM coming in the back of an outdoor surface mounted disconnect enclosure is prohibited. I must have missed that thread. I've never seen anything other than just this on resi work.
 
jetlag said:
I read the post on NMB to AC . There was a short pvc outside up to DISC switch. The replies were the NMB must terminate in box before leaving the house and continue on with thwn. My guestion is if NMB runs thru outside wall into back of a surface mounted WP fixture box is the wire considered outside and against code? What if the box is flush mounted, does that make it not outside. I guess we should run NMB to the switch and short piece UF to light?
Click to expand...


It is and has been accepted practice to supply the types of installations you have mentioned with NM cable.
 
The only thing to remember is to leave enough NM sticking outside the wall that you can chop off a few inches off the tail if you live in a wet are to have fresh, dry, conductors.

Think about all the houses you've seen under constuction. Didn't they have romex stuck out, and curled a couple of times? If not, I'd be checking with the AHJ, because it's okay in most areas.
 
scrool down to NM in conduit by torcho

scrool down to NM in conduit by torcho

mdshunk said:
Not sure why anyone thinks NM coming in the back of an outdoor surface mounted disconnect enclosure is prohibited. I must have missed that thread. I've never seen anything other than just this on resi work.
Click to expand...

Thats the only way Ive seen it done also. There was a short pvc stub up to disc. not sure if that cause the replies on the other post
 
They all use romex

They all use romex

Rockyd said:
The only thing to remember is to leave enough NM sticking outside the wall that you can chop off a few inches off the tail if you live in a wet are to have fresh, dry, conductors.

Think about all the houses you've seen under constuction. Didn't they have romex stuck out, and curled a couple of times? If not, I'd be checking with the AHJ, because it's okay in most areas.
Click to expand...

They all stub out romex same as me. But the post replies are "NMB in conduit" are calling this a wet location, in which of course NMB is not allowed
 
Didn't pay attention to the "in conduit" part.
 
jetlag said:
Thats the only way Ive seen it done also. There was a short pvc stub up to disc. not sure if that cause the replies on the other post
Click to expand...

Jetlag-- there is no problem if you feed an outdoor light fixture with NM cable. The problem is when you leave the house and try to use nm in conduit. NM is not rated for outdoor in a wet location. Certainly the box you installed for an outdoor fixture on the house is not a wet location.
 
Outdoors and underground is a wet location. Outdoors, in a raceway, (but not underground) should be a dry location. What's the difference between NM in an outdoor raceway and NM under roof? They're both protected from the weather.
 
mdshunk said:
Outdoors and underground is a wet location. Outdoors, in a raceway, (but not underground) should be a dry location. What's the difference between NM in an outdoor raceway and NM under roof? They're both protected from the weather.
Click to expand...

Outdoors in a raceway is not considered dry location.
 
mdshunk said:
Outdoors and underground is a wet location. Outdoors, in a raceway, (but not underground) should be a dry location. What's the difference between NM in an outdoor raceway and NM under roof? They're both protected from the weather.
Click to expand...


Marc can you run thhn in a conduit on a building outdoors?
 
mdshunk said:
Doesn't matter. Nobody presently markets THHN that isn't also rated as THWN. :wink: If they did, I would answer YES.
Click to expand...

Marc in my opinion the inside of raceways located in wet locations are 'wet locations'.

In 2008 they will make this clear.

Regardless it's hard to explain the need for 225.22 if the NFPA did not already consider the inside of outdoor raceways to be wet locations.
 
mdshunk said:
Doesn't matter. Nobody presently markets THHN that isn't also rated as THWN. :wink: If they did, I would answer YES.
Click to expand...

I think the issue is the condensation in a conduit outdoors. I believe you'd be in violation if you ran non wet location wire outdoors in conduit even if it is above grade
 
Dennis,

Check in your code book, in chapter 100, in locations,for definitive qualifications.

THHN per table 310.13 state THHN is for dry and damp locations.
 
Rockyd said:
Dennis,

Check in your code book, in chapter 100, in locations,for definitive qualifications.

THHN per table 310.13 state THHN is for dry and damp locations.
Click to expand...

Yes but not wet location.

Read art. 334.12(B)(4)
 
Hey Bob,


Is it just a manufacturer's issue that they rate romex as thhn, rather than the typical dual listing of thwn/thhn?
 
Rockyd said:
Hey Bob,


Is it just a manufacturer's issue that they rate romex as thhn, rather than the typical dual listing of thwn/thhn?
Click to expand...

The fact is that the wire in nm cable is probably thhn/thwn but it isn't marked.
 
Status
Not open for further replies.
Top