Running conduit outside of a house, how to come into a box?

[PowerSupportElec]

I know that the best answer is not to run conduit outside of the house, to fish it in the walls instead. But sometimes that just won't work, or the customer doesn't want it.

I have to add a new receptacle in the outside wall of a second story room for a window air conditioner. The attic space is completely close off and the customer doesn't want any walls cut. THe easiest way to do this is to come out of the basement through the rim joist, LB a 1/2 raceway upwards, then LB back into the house right behind the new single gang box that I cut in.

THe problem with this is that it could be a bit difficult to get the pipe cut the correct length to match up with the new-work box cut into the wall. Even if I bring a helper with me to work outside while I am inside, it's still a pain.

I was wondering if anyone had any tips for this situation? This is getting inspected so it has to be code compliant.

I was thinking about installing UF in the raceway instead of THWN. This would allow me to come out of the LB at the top and free-air the UF into the box. Any concerns with doing that? Any other tips or tricks?

 

[growler]

THe problem with this is that it could be a bit difficult to get the pipe cut the correct length to match up with the new-work box cut into the wall. Even if I bring a helper with me to work outside while I am inside, it's still a pain.

I was wondering if anyone had any tips for this situation? This is getting inspected so it has to be code compliant.

Any other tips or tricks?

First off, even if it wasn't getting inspected it would still need to be code compliant.


Second, some things are just not all that easy (fact of life).


I would rather take the time to run the conduit corectly than pull UF cable in conduit. I don't see it as being a big problem if you measure correctly.

Again, some things are just not as fast as running conduit out in the open and that's why we charge more for a job like this.

 

[mjf]

I know that the best answer is not to run conduit outside of the house, to fish it in the walls instead. But sometimes that just won't work, or the customer doesn't want it.

I have to add a new receptacle in the outside wall of a second story room for a window air conditioner. The attic space is completely close off and the customer doesn't want any walls cut. THe easiest way to do this is to come out of the basement through the rim joist, LB a 1/2 raceway upwards, then LB back into the house right behind the new single gang box that I cut in.

THe problem with this is that it could be a bit difficult to get the pipe cut the correct length to match up with the new-work box cut into the wall. Even if I bring a helper with me to work outside while I am inside, it's still a pain.

I was wondering if anyone had any tips for this situation? This is getting inspected so it has to be code compliant.

I was thinking about installing UF in the raceway instead of THWN. This would allow me to come out of the LB at the top and free-air the UF into the box. Any concerns with doing that? Any other tips or tricks?

Make use of an expansion coupling. If your cut is within an inch or two you'll be home free.

 

[PowerSupportElec]

Make use of an expansion coupling. If your cut is within an inch or two you'll be home free.

Now that's definitely a good idea, but I am afraid that an expansion coupling is too long to fit between the LB and the back of the box in a typical 2X4 framed wall.

 

[mjf]

Now that's definitely a good idea, but I am afraid that an expansion coupling is too long to fit between the LB and the back of the box in a typical 2X4 framed wall.

hahahahaha.....I thought you meant your height measurement for your vertical rise.

Are you using an old work gem cut-in box? Do they even have a knockout for a TA?

 

[suemarkp]

Use PVC conduit and cut it to the right length (trial fit, knowing the fitting will slide in deeper when it has slippery glue). If you get it wrong, it is cheap to do again. Plus, you have some length flexibility since it is a glued connection (need enough length to get a good glue bond, but you don't have to bottom the pipie in the LB hole).

 

[Smart $]

Not that I recommend it but...

225.10 Wiring on Buildings. The installation of outside
wiring on surfaces of buildings shall be permitted for circuits
of not over 600 volts, nominal, ..., as Type UF cable, ...

...but then the question of whether the AHJ will consider any part as subject to damage and require it be protected with conduit.

 

[ActionDave]

I was wondering if anyone had any tips for this situation? ?

Go ahead and drill your hole a little oversized. Use an SLB, insert a reducing washer between the EMT connector and the SLB to cover the slop in your hole.

 

[mjf]

Use PVC conduit and cut it to the right length (trial fit, knowing the fitting will slide in deeper when it has slippery glue). If you get it wrong, it is cheap to do again. Plus, you have some length flexibility since it is a glued connection (need enough length to get a good glue bond, but you don't have to bottom the pipie in the LB hole).

:thumbsup::thumbsup::thumbsup:

 

[GOZ]

Measure twice, Cut once.

Measure twice, Cut once.

I know that the best answer is not to run conduit outside of the house, to fish it in the walls instead. But sometimes that just won't work, or the customer doesn't want it.

I have to add a new receptacle in the outside wall of a second story room for a window air conditioner. The attic space is completely close off and the customer doesn't want any walls cut. THe easiest way to do this is to come out of the basement through the rim joist, LB a 1/2 raceway upwards, then LB back into the house right behind the new single gang box that I cut in.

THe problem with this is that it could be a bit difficult to get the pipe cut the correct length to match up with the new-work box cut into the wall. Even if I bring a helper with me to work outside while I am inside, it's still a pain.

I was wondering if anyone had any tips for this situation? This is getting inspected so it has to be code compliant.

I was thinking about installing UF in the raceway instead of THWN. This would allow me to come out of the LB at the top and free-air the UF into the box. Any concerns with doing that? Any other tips or tricks?

From the inside, drill a 1/4" pilot hole through the cutout to the outside wall where your conduit will be. From the outside, use a hole saw the diameter of the hub on th LB to drill your hole. Measure the distance through the hole, from the back of the box to the outside surface of the wall. That is the length you should need including your connector. Test fit before you glue. Take the time to get the conduit right and use the THWN. Otherwise you will waste more time fighting UF into the 1/2" conduit.

 

[renosteinke]

Use an SLB on the outside; this will let you run the pipe flat against the house.

Your inside box needs to be metal. Connect the box to the SLB with a piece of 'running thread' cut to length. Using a 'deep' box, and entering the box at a corner, makes more room for the device. If you're using an 'old work' box, you might want to use a 2-gang type.

 

[bobbymari]

or instead of the lb on top use a bell box and you can just use a small romex jumper from exterior bellbox to interior cut in box and make up in exterior box. 2 screw metal romex connectors

 

[James S.]

or instead of the lb on top use a bell box and you can just use a small romex jumper from exterior bellbox to interior cut in box and make up in exterior box. 2 screw metal romex connectors

This is what I was thinking. Is there any reason you can't use a bell box instead of the LB?

 

[PowerSupportElec]

This is what I was thinking. Is there any reason you can't use a bell box instead of the LB?

No, it's just that the bell box stands out more.

 

[James S.]

No, it's just that the bell box stands out more.

I agree with you most of the time on wanting to do the best looking job possible but I think this is one of those situations where it is going to be ugly either way. If the owner wanted the prettiest install you would be cutting the drywall to get the wire in the wall.

 

[jiggawatt79]

I think the bell box is the best option. It is bulkier but covers the hole better than an SLB.

 

[Smart $]

I think the bell box is the best option. It is bulkier but covers the hole better than an SLB.

I thought someone would catch on when I made post #7. :roll:

Just run UF out the back of the box and through the exterior hole (drill downward to accomodate in wall bend, so as to not have the p bend outside). Run conduit up and seal end (e.g. duct seal, cable gland). No bell box, no LB/SLB, no conduit transition in wall.

 

[Dennis Alwon]

I agree with Smart. Why would you want to connect the pvs to the box. Drill a hole below the box in the same cavity and reach in and grab the UF and install it in an old work box.

 

[busman]

I would put a piece of 1/2" PVC on the back of the Gem Box such that the conduit is over length to go thru the wall. Then mark for the hole and drill a hole large enough for the flange on a 1/2 LB to fit thru with a little slop. I'd install the gem box securely with the conduit thru the hole and out the wall. Then go around the outside and use a flush cut (oscillating) saw to cut the PVC flush with the outside finish surface. Then just put cement on the LB and push into place on the trimmed conduit. DONE.

Mark

 

[Fulthrotl]

I know that the best answer is not to run conduit outside of the house, to fish it in the walls instead. But sometimes that just won't work, or the customer doesn't want it.

I have to add a new receptacle in the outside wall of a second story room for a window air conditioner. The attic space is completely close off and the customer doesn't want any walls cut. THe easiest way to do this is to come out of the basement through the rim joist, LB a 1/2 raceway upwards, then LB back into the house right behind the new single gang box that I cut in.

THe problem with this is that it could be a bit difficult to get the pipe cut the correct length to match up with the new-work box cut into the wall. Even if I bring a helper with me to work outside while I am inside, it's still a pain.

I was wondering if anyone had any tips for this situation? This is getting inspected so it has to be code compliant.

I was thinking about installing UF in the raceway instead of THWN. This would allow me to come out of the LB at the top and free-air the UF into the box. Any concerns with doing that? Any other tips or tricks?

cut in a deep bowers box, the kind that uses battleships to lock it in,
dry fit, mark a KO out the back, and carefully holesaw the wall, so
you have a hole out the back.

dry fit again, and get a measurement out the back of the box, so you
know how long to cut the emt. put the right length nipple of emt out
the back of the box, so it sticks out 1/2" past the finished surface of
the exterior.

scooch up a ladder, and use a 1/2" SLB with a stick of pipe on it and
run to where you need it to go. i'd use 3M 550 sealant to weatherproof.

don't use jacketed cable inside 1/2" inside conduit. dunno if it's allowed
now, but it didn't use to be, and it's a cheezy thing to do even if the
code permits it.

screams "hacking trunk slamming home depot parking log genius".