running thwn wire

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Old 05-11-10, 07:17 AM
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running thwn wire

Hello,
I want to run 2 20amp circuits from my panel to an outside BBQ island. I have 3/4" pvc run underground outside to the island. It comes off the house in a junction box. My question is, Should I run romex from the panel to the junction box and then run thwn wire to the island or should I run thwn wire the entire way? Also, should there only be 4 thwn wires in the conduit for the 2 20amp breakers? 1 green, 1 white, 1 black and 1 red? Or should I run 2 black 2 green and 2 white?

Thanks for any help!!!
 
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Old 05-11-10, 07:31 AM
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Originally Posted by mattypNY View Post
Hello,
I want to run 2 20amp circuits from my panel to an outside BBQ island. I have 3/4" pvc run underground outside to the island. It comes off the house in a junction box. My question is, Should I run romex from the panel to the junction box and then run thwn wire to the island or should I run thwn wire the entire way? Also, should there only be 4 thwn wires in the conduit for the 2 20amp breakers? 1 green, 1 white, 1 black and 1 red? Or should I run 2 black 2 green and 2 white?

Thanks for any help!!!
You may run romex to the box if you like, or you may utilize pipe and pull wires. Either is acceptable. Please remember to duct seal your conduit where it leaves the building, it is required that you do so and it greatly improves the lifetime of electrical parts exposed to change in temperature.

You need only run 1 green. You may run 1 or 2 whites. If you run 1, both colored wires must land on the same 2 pole breaker. If you have 2 whites that go all the way back to the panel, you can use two single pole breakers.
 
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Old 05-11-10, 07:48 AM
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Originally Posted by RHefferan View Post
You may run romex to the box if you like, or you may utilize pipe and pull wires. Either is acceptable. Please remember to duct seal your conduit where it leaves the building, it is required that you do so and it greatly improves the lifetime of electrical parts exposed to change in temperature.

You need only run 1 green. You may run 1 or 2 whites. If you run 1, both colored wires must land on the same 2 pole breaker. If you have 2 whites that go all the way back to the panel, you can use two single pole breakers.

I was going to put a 20amp GFI breaker and just a regular 20 amp breaker. The 20 amp GFI breaker is going to be for all the outlets on the island and the 20 amp breaker is for the fridge.

So I can run 2 whites, 2 blacks and 1 green? How does the ground get wired through when only running the one?
 
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Old 05-11-10, 07:50 AM
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Your outside receptacles will need GFI protection and weatherproof in use covers.
 
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Old 05-11-10, 08:13 AM
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Originally Posted by pcboss View Post
Your outside receptacles will need GFI protection and weatherproof in use covers.
that is why I was putting the outlets on a GFI circuit breaker. I was told that the exception to the GFI protection outside was the fridge. That it did not need a gfi receptacle since I was putting it on a dedicated circuit. Is that not true?
 
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Old 05-11-10, 08:34 AM
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Originally Posted by mattypNY View Post
I was told that the exception to the GFI protection outside was the fridge. That it did not need a gfi receptacle since I was putting it on a dedicated circuit. Is that not true?
The fridge does not require a GFCI only if your area follows 2005 NEC or earlier and the receptacle is not exposed to the outdoors such as inside a shed or garage.

If your area follows 2008 NEC, all exceptions for fridges have been removed -- GFCI is required. If the receptacle is exposed it must be GFCI, have an in-use cover and be WR "weather-resistant" type.
 
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Old 05-11-10, 08:37 AM
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Originally Posted by ibpooks View Post
The fridge does not require a GFCI only if your area follows 2005 NEC or earlier and the receptacle is not exposed to the outdoors such as inside a shed or garage.

If your area follows 2008 NEC, all exceptions for fridges have been removed -- GFCI is required. If the receptacle is exposed it must be GFCI, have an in-use cover and be WR "weather-resistant" type.
So can I just run a double pole 20amp gfi breaker and use in-use covers for all the receptavles on the BBQ island? (that way, the fridge should still be on it's own circuit and the other receptacles will be on another)

the receptacles for the BBQ island will all be inside the island , 2 will be on the counter top outside. Does that make a difference?
 
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Old 05-11-10, 08:44 AM
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If it's not a fully roofed structure, the NEC considers it to be outside.

A double-pole 20A GFCI breaker would be okay, but may be prohibitively expensive depending on your panel brand. I would consider two separate circuits with separate single-pole GFCI breakers or receptacles. This will also prevent a fault on the other circuit from taking down your fridge.
 
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Old 05-11-10, 09:01 AM
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Originally Posted by ibpooks View Post
If it's not a fully roofed structure, the NEC considers it to be outside.

A double-pole 20A GFCI breaker would be okay, but may be prohibitively expensive depending on your panel brand. I would consider two separate circuits with separate single-pole GFCI breakers or receptacles. This will also prevent a fault on the other circuit from taking down your fridge.
So 2 single pole GFI breakers would be ok and no need for GFI receptacles then.

Then I can wire with the THWN wire with 2 black, 2 white and 1 dedicated ground for both single pole GFI breakers? How does the ground get wire in that way?
 
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Old 05-11-10, 09:20 AM
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Yes, 2 black, 2 white, and a green is probably your best option, IMHO. As ibpooks indicates, single pole GFCI breakers are quite a bit cheaper than a doube pole GFCI breaker. The cost of the extra wire is probably far cheaper than the double pole breaker.

The green runs to every box and creates the grounding system for both circuits. Connect it to all boxes and devices you use for both circuits.
 
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Old 05-11-10, 09:28 AM
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Originally Posted by RHefferan View Post
Yes, 2 black, 2 white, and a green is probably your best option, IMHO. As ibpooks indicates, single pole GFCI breakers are quite a bit cheaper than a doube pole GFCI breaker. The cost of the extra wire is probably far cheaper than the double pole breaker.

The green runs to every box and creates the grounding system for both circuits. Connect it to all boxes and devices you use for both circuits.
So the ground can just do one big loop from the panel to each outlet and then the gfi breaker dedicated line for the fridge will have a homerun black and white and the other gfi breaker can just loop through the 4 outlets?

Is there a problem with running 2 grounds or just not necessary?
 
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Old 05-11-10, 10:37 AM
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It's just not necessary. If it makes you feel better to have a ground wire for each circuit, the only limitation would be space in your conduit.
 
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Old 05-11-10, 10:49 AM
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Originally Posted by RHefferan View Post
It's just not necessary. If it makes you feel better to have a ground wire for each circuit, the only limitation would be space in your conduit.
I have 3/4" conduit and will be running 2 black, 2 white and 1 ground for 2 20 amp GFI breakers.

There shouldn't be a problem with that will there (enough room and no need to worry about heat)?
 
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Old 05-11-10, 11:02 AM
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You can fit 6 #12 THHN/THWN conductors into a 3/4" PVC with room to spare. There are 4 current carrying conductors, so derating based on heating is a necessity, but with 90 degree wire (THHN or THWN-2 wire is 90 degree rated) you can derate from the 90 degree amperage, which leaves you plenty of capacity for a 20A circuit.

So, in short, go right ahead with 6 wires in your 3/4" PVC if that extra green makes you feel better. It's fully within code.
 
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Old 05-11-10, 11:12 AM
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Originally Posted by RHefferan View Post
You can fit 6 #12 THHN/THWN conductors into a 3/4" PVC with room to spare. There are 4 current carrying conductors, so derating based on heating is a necessity, but with 90 degree wire (THHN or THWN-2 wire is 90 degree rated) you can derate from the 90 degree amperage, which leaves you plenty of capacity for a 20A circuit.

So, in short, go right ahead with 6 wires in your 3/4" PVC if that extra green makes you feel better. It's fully within code.
Only problem will be getting the 14/3 romex wire out of the conduit. Contractor put that in for one circuit and when I called him on it he said he would fix it and then I never heard back from him. I do have an electrician coming to wire it all up so the permits are good just wanted to make sure everything is right.

Think there will be a problem pulling the romex wire out of the 3/4" conduit? It is about 16' of conduit with 2 90s...
 
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Old 05-11-10, 11:25 AM
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For only 16' it shouldn't be a problem to get it out. Just get some vice grips on the wire and pull. If it's really stuck mix up a mild dish soap solution and shoot it through the conduit with an air compressor or shop vac.

After the old wire is out, shop vac the liquid out of the conduit and swab it by pulling through a rag on a string until it comes out reasonably clean.
 
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Old 05-11-10, 12:29 PM
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Originally Posted by ibpooks View Post
For only 16' it shouldn't be a problem to get it out. Just get some vice grips on the wire and pull. If it's really stuck mix up a mild dish soap solution and shoot it through the conduit with an air compressor or shop vac.

After the old wire is out, shop vac the liquid out of the conduit and swab it by pulling through a rag on a string until it comes out reasonably clean.
thanks for everyone's help!
 
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Old 05-13-10, 08:02 AM
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Help! :)

I just spoke with an electrician who is telling me that the new NEC code is that a direct bury cable must be used and that it can be run in conduit. Not individual wires. Is this true?

Thanks!
 
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Old 05-13-10, 08:20 AM
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Originally Posted by mattypNY View Post
I just spoke with an electrician who is telling me that the new NEC code is that a direct bury cable must be used and that it can be run in conduit. Not individual wires. Is this true?

Thanks!
If your PVC runs, without interruption, from a box in your house to a box on the BBQ island, then he's wrong. THWN is perfectly acceptable.

He may be confusing that the new code classifies all underground pipes as wet locations as meaning you need direct burial cable. This is not true, so long as you use wires which are rated for wet locations, and that's what the W in THWN tells you.

Rich
 
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Old 05-13-10, 08:29 AM
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Originally Posted by RHefferan View Post
If your PVC runs, without interruption, from a box in your house to a box on the BBQ island, then he's wrong. THWN is perfectly acceptable.

He may be confusing that the new code classifies all underground pipes as wet locations as meaning you need direct burial cable. This is not true, so long as you use wires which are rated for wet locations, and that's what the W in THWN tells you.

Rich
Can I run romex wire from the box in the house to the junction box on the outside of the house and then THWN wire from there (through the PVC to a box on the BBQ island)? Or does it have to be completely in PVC from the panel?>
 
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Old 05-13-10, 08:48 AM
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It just has to be continuous from box to box to utilize wire instead of direct burial cable. You can use romex from the panel to the interior box, then THWN from the interior box to the BBQ island box, provided the conduit run is continuous from box to box.

I only make that qualification because to use single wires you need continuous conduit, for protection of the wiring. It sounds like that's what you have, but I don't want to give you bad advice on an assumption.
 
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Old 05-13-10, 08:55 AM
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You can run NM-b (Romex) inside the house to an exterior facing box. No conduit required.

Just a minor and moot point if the contractor really did run Romex (NM-b) not UF in the conduit that was a code violation.
 
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Old 05-13-10, 08:55 AM
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Originally Posted by RHefferan View Post
It just has to be continuous from box to box to utilize wire instead of direct burial cable. You can use romex from the panel to the interior box, then THWN from the interior box to the BBQ island box, provided the conduit run is continuous from box to box.

I only make that qualification because to use single wires you need continuous conduit, for protection of the wiring. It sounds like that's what you have, but I don't want to give you bad advice on an assumption.


But the romex to thwn connection has to be in an interior box? I cannot conect in the outside junction box?


Right now I have romex running from the panel inside going outside the house and then through pvc to the BBQ island. There is a junction box on the house where the romex comes trhough and then the conduit runs under the cement patio slab and comes up through the cement into the BBQ island...
 
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Old 05-13-10, 09:21 AM
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It could be an exterior box to exterior box as well. I only said interior box because I thought that was the situation, my apology for adding confusion.

The only thing to worry about is that, for a wire run, there is always conduit protecting the wire. So long as the conduit is continuous, you're alright.
 
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Old 05-13-10, 09:28 AM
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Originally Posted by RHefferan View Post
It could be an exterior box to exterior box as well. I only said interior box because I thought that was the situation, my apology for adding confusion.

The only thing to worry about is that, for a wire run, there is always conduit protecting the wire. So long as the conduit is continuous, you're alright.
Thanks!

So it is ok to run romex from the panel to the outside junction box and then make the connections there to the individul THWN wires that will run in continuous pvc...

(and in that situation the 2 ground wires from the two romex wires can be wired to the 1 ground wire run through the pvc?)
 
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Old 05-13-10, 11:46 AM
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You are asking about bringing the Nm into the back of a box mounted on the exterior of the house? From that box you are switching to a PVC conduit using wet rated conductors.
 
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Old 05-13-10, 12:27 PM
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Originally Posted by pcboss View Post
You are asking about bringing the Nm into the back of a box mounted on the exterior of the house? From that box you are switching to a PVC conduit using wet rated conductors.
That is exactly what I am saying. Or should i bring the THWN line all the way to the panel inside (in conduit)?
 

Last edited by mattypNY; 05-13-10 at 01:50 PM.
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Old 05-13-10, 02:26 PM
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It is code compliant to run NM-b to a box mounted on an exterior wall. Conduit is not needed.
 
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Old 05-21-10, 06:12 AM
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Thanks again for all the help. I had an electrician at the house yesterday and he ran the THWN stranded wire from the panel to the BBQ. 2 circuits on 20amp breakers and each circuit goes to a GFI outlet. (Cheaper for me).

I had a question about the pvc he used inside the house. He used 3/4" gray pvc tubing. It says Liquid Tite NM 3/4" on the tubing. It also says direct burial.

Is this ok to run in the house to the service panel?
 
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Old 05-21-10, 07:45 AM
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In my opinion Liquid Tite is expensive over kill for inside. However it is certainly acceptable and code compliant.
 
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Old 05-21-10, 07:46 AM
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Yes that is okay...............
 
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Old 05-21-10, 07:50 AM
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I think it was all he had on him. He did run about 20 feet of the stuff inside. Just wondering if that was within code. Especially since it states it is for burial.

So I should be ok with that?
 
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Old 05-22-10, 07:56 AM
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Originally Posted by mattypNY View Post
I think it was all he had on him. He did run about 20 feet of the stuff inside. Just wondering if that was within code. Especially since it states it is for burial.

So I should be ok with that?

LFNMC is just fine. Probably all he had with him.
 
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