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I'm in the middle of a kitchen remodel and have hit a slight snag and need some advice on how to proceed. I'm moving the oven into an island, which requires moving the 240 line used for the oven.

The original plan was to relocate the current 240 line into the utility room and then run a new line from there to the oven, and splice these connections in a junction box. However this plan is not panning out as the old 240 line is aluminum, not copper, and is only 2 hots and shared ground/neutral rather then the R/B/W/G 4-wire copper that is commonly used today. Mixing aluminum and copper is not a good idea, so rather than proceed with this plan I'd like to look at alternatives.

Option 1

Run a new 240 line from the breaker box to the location needed for the island. This is what I'd like to do, but I'm unsure of the type of wire and conduit to use. Here is a picture of the back of the house, with breaker box, with the red line being an idea of where to run conduit for this wire:

Exterior breaker box with planned run

My questions are, which conduit do I use; EMT or PVC (such. 80 of course)? And which wire do I use? This wire will run right in-between the floor joists when it enters the house, so individual wires probably won't work, so what insulated wire should I use? UF is the only option, right? This will be a 40 amp circuit, so I was thinking 6 gauge, just for overkill.

Option 2

Since I've already got the new copper wire ran from the basement utility room to the island location, I could just run individual THWN through conduit from the breaker box straight down and in to the utility room and then splice this in a junction box to the wire I already ran. At least in this case I'm splicing copper to copper which makes me less nervous. But the individual wires need to be in conduit inside the house as well, correct? How do I handle the area from where the wires enter the house until they hit the junction box (about 4-5 feet maybe)?

Also, here is a shot of the area where the line would come in to the utility room. You can see the new NM 6-3 wire right next to the old aluminum wire there on the right, with the outside of the house being on the left. The original plan was to just splice those two together...

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So that's where I'm at. Any and all help/advice is greatly appreciated.

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    For large wire aluminum is still both common and safe (if properly terminated) - the "scary aluminum wiring" issues were with 10&12 gauge for outlets and lights. You would need to add a ground or neutral, but there's nothing against using aluminum all the way. – Ecnerwal Apr 6 '15 at 22:17
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Of the options you are considering, I'd think option 2 makes more sense, and 4-5 feet of conduit - in most cases the conduit will just be continuous from the junction box right through the wall, no particular fuss "as it enters the house" - Come down the wall, put on an LB, drill a hole in the wall, insert conduit, connect to junction box, connect to LB; done. This might be aided by drilling at least a pilot hole from the inside out to make lining it all up easier. Also pick up some duct seal (gray putty, in the electrical aisle) to pack the wires as they leave the LB.

If the wires are entering via an existing conduit, you just need to connect a new conduit to the box that conduit terminates in, and your junction box.

EMT or PVC is six on the one hand, half a dozen the other. I use metal aboveground and PVC below, mostly.

  • Awesome, thanks for the fast reply! Just a couple of follow-up questions: What's the purpose of the duct seal in the LB? And is it possible/code-compliant to take the PVC conduit as it enters the house and then join it with some flexible metal conduit to the junction box? Basically I'm concerned about clearance and I'm not sure if I can get 3/4" conduit flush against the joist all the way to the outside; there are some water pipes real close I need to navigate around. I added a picture of the area-in-question above so you can see the area I'm working with. Thanks! – Matt DeWitt Apr 7 '15 at 20:21
  • The duct seal is to help cut down on traffic from inside to outside in the conduit - air leakage, water, insects... You can use any flavor of conduit you like. You'll want a new junction box for this - the one on that light almost certainly does not have the cubic inches for 4 #6 plus the wiring it has. You can put EMT conduit in standoffs (or standoffs on blocks) to clear your pipes, or put 4 small bends in it to help with clearance. Unless you have a roll of it on hand, the flexible stuff gets expensive fast .vs. EMT. Throw some pipe insulation on the hot water lines while you are at it. – Ecnerwal Apr 8 '15 at 11:23
  • Right, you said PVC, not EMT - still, same deal, you can put it on blocks or pop 4 45"s on it to make a pipe bump, and that will cost less than a fitting to change to threads, a fitting to change threads to flex metal, a roll of flex metal you won't use most of, and another fitting at the end of the flex metal to connect to the box. I'd use blocks, probably. – Ecnerwal Apr 8 '15 at 11:34
  • Thanks again! I was definitely planning a new box; I've got a deep 4" metal box, so should hold the 2 set of wires and 4 splices. The duct seal makes sense; don't want any leaks! – Matt DeWitt Apr 8 '15 at 15:32

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