Ask Me Help Desk - Mixing old and new wire

Live in a circa 1940's home with old non-grounded NM cable, cloth outer shell, insulated wires. There are currently 14 outlets on 1 circuit, in addition to 5 ceiling lights. Obviously the circuit is overloaded.

I'm planning on running 3 new circuits (living room, bedroom, dining room are currently on this one circuit) and having each room on it's own circuit. About 5 outlets per room, and then all of the lights will stay on the old circuit.

My question is: this will take sometime to run new circuits/cable/outlets, so can I tie in old wire to the new wire as I go so I still have power to everything in between working? I only have about 1 hour a night, and maybe 6 hours total on the weekends to work on this so it will be a slow conversion. I obviously don't want to have no power on circuits that are downstream for extended periods.

FYI-I'm running all #12 wire with 20 amp circuits (arc fault for the bedroom). I'll be replacing #14 wire. Once the conversion is complete it will be all #12. Because of the #14 should I put in 15 amp circuits temporarily until all of the wire has been replaced?

Also, any tips on pulling cable from the old pros? I'll be coming up from the basement, and there is ZERO insulation in the walls, so I'm hoping pulling the cable will be smooth.

It would be safer to have a 15A breaker when the minimum size is 14 AWG. You could pigtail this in the breaker to the existing circuit until it's all 20 Amp.

It would be wise to use a stud finder with AC detection or similar device to try to locate wires within the wall you are drilling. There are large steerable drill bits which are like 5' long which can be use to drill between walls. They also include a hole at the beginning of the bit to attach pulling string through.

Since most boxes are attached to the studs, your only choice may be to poke some holes near the outlets and use this to run wires and then patch the drywall when finished.

Peter,

What ever AWG you settle on, it must match the breaker. If you choose to use a 15 amp breaker, then you can use 14/2 AWG. However if you choose to run 20 Amps, then you must use at least 12/2 or 12/3, if two switches will control one light.

My biggest concern here is that you appear not to know exactly what you are doing. Therefore, I suggest that you call several electricians and get bids.

I also strongly suggest that you consider changing out the wiring as well as the main power panel box. I suspect that you have fuses now and not breakers and we know that the wiring is very old and may be split or bare in different places. Given the circuit design, many lights and outlets also suggests that this house is not wired according to the current level of NEC Code.

Please call an electrical inspector or licensed electrician to go over the wiring.

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Originally Posted by donf

Peter,

What ever AWG you settle on, it must match the breaker. If you choose to use a 15 amp breaker, then you can use 14/2 AWG. However if you choose to run 20 Amps, then you must use at least 12/2 or 12/3, if two switches will control one light.

My biggest concern here is that you appear not to know exactly what you are doing. Therefore, I suggest that you call several electricians and get bids.

I also strongly suggest that you consider changing out the wiring as well as the main power panel box. I suspect that you have fuses now and not breakers and we know that the wiring is very old and may be split or bare in different places. Given the circuit design, many lights and outlets also suggests that this house is not wired according to the current level of NEC Code.

Please call an electrical inspector or licensed electrician to go over the wiring.

Thanks for the response Don,

Actually, the panel has already been replaced, it's about 6 years old. My prime concern was if this is feasible to do in sections, as opposed to at onetime. Again, all of the new circuits will be 20 amp circuits with #12 wire... but I'm assuming I should use 15 amp breakers until ALL of the #14 wire has been replaced with #12. Am I wrong in assuming that a 15amp breaker can have #12 wire attached to it?

I've been a rough carpenter for about 9 years, as well as an architect for 3, so I'm not totally lost on what I'm going to be doing. I don't have the money to hire an electrician. I actually just got off the phone with the local building department, and got an appointment to take my plans in to meet with the electrical inspector for an informal review.

Good plan to keep the 15 amp breaker active until the entire circuit is upgraded to all #12, sounds like your on the ball. It takes a bit for others to realize what the real question is sometimes and they head off in a different direction circling the question.

Quote:

been a rough carpenter for about 9 years, as well as an architect for 3, so I'm not totally lost on what I'm going to be doing.

I respect this! Yet, are you saying you have some idea as far as the electrical part of the project?

Washington,

Your plan is fine. You cannot place a 20 Amp breaker on a 14/2 line. 14/2 is rated at 15 amp. 12/2 or 12/3 is rated for 20 amp. You can use a 15 amp breaker on a 20 amp line providing both the breaker and load are rated at 15 amps.

One additional comment. 15 amp switches and outlets can be attached to a 12/2 or 12/3 without violating the NEC Code.

Quote:

Originally Posted by Washington1

I respect this! Yet, are you saying you have some idea as far as the electrical part of the project?

Yes, through carpentry and architecture I've picked up many things regarding electrical work. Though, outside of rewiring my kitchen, which was torn down to bare studs I've never run new electrical cable through old work. This is where my question came from.

You might run into boxes which have the cable clamps on the outside in a house that old. Tough to pull the old cable out if not impossible. You may be better off just cutting out the wall but it may be button board which is a whole different animal than sheetrock. They are both gypsum product so the patching will stick though. Get a Greenlee fishing pole or make one from an actual old fishing pole like the old days, leave the tip eye on and remove all the rest.doing receptacles from the basement is fine but the lights are going to have to have their cable up to the ceiling unless you use lamps on switched outlets. In the attic you can find your wall with the switch on it by pushing insulation aside and finding the top plate, if the old cable from the switch is there you already have a hole. If you cut out the old switch box you can usually get to the first staple above the box and remove it. Yanking hard on this cable from the top will get it out one way or the other sometimes any other staples too, I got lucky in my 1957 era house because they only used one staple next to the box. You can also wrap the old cable a couple of inches above the handle of your linemans pliers and lever it up and out of the hole.