Help! Wiring for new dryer

**eric3872** · 05-07-2011, 07:23 AM

I need help... I received two proposals from two separate electricians for wiring a new dryer. Here is the situation: The room has a dedicated 220V 20 amp outlet wired to a 20 amp breaker (it was originally intended for an air conditioner, but will not be used for that purpose). I realize that the new dryer will require a 30 amp receptacle. One electrician tells me that the 20 amp breaker has to be replaced with a 30 amp breaker and a new wire run up to the location of the new 30 amp receptacle. The second electrician says that there is no need to run a new wire since there is already a 220v outlet in the room. He says that the breaker should be changed to a 30 amp breaker and the 20 amp outlet can either be replaced or tapped into for the new 30 amp outlet. One of them is right and one is wrong... Neither of them looked at the gauge of the existing wire before making their assessment. Any advice would be greatly appreciated.

**cacher_chick** · 05-07-2011, 07:38 AM

You have not told us what we need to know to properly answer the question.

To properly wire the circuit, the wire must be a minimum of 10 gauge. There also must must be 4 wires, 2 being the "hot" wires, and the others being neutral and ground.

Older installations do not have a ground wire, which is no longer permitted by code.

Electrician #1 sounds like he is on the right track.

**eric3872** · 05-07-2011, 08:20 AM

All the wiring is fairly new. The house was gut renovated 2 years ago (before I bought it). All new electrical service was installed, however that does not necessarily mean it was done properly. I do not know what gauge the wire is, but will check. Assuming the conditions you describe are present (10g wire and 4 wires), could the scenario proposed by electrician # 2 work?

hj · 05-07-2011, 08:25 AM

Just because there is "already a 220/240 outlet in the room" has NOTHING to do with the question, UNLESS it has 10/3 w/g wires to it, which is NOT likely for a 20 amp circuit. (IN fact, an airconditioner would only have required 10/2 w/g wires since they do not have a 110v control circuit which would have required the third wire/neutral.) Connecting a #12wire to a 30 amp circuit breaker is a PERFECT way to burn the house down. Do NOT even consider doing business with the second "electrician" for ANYTHING, unless he is correct and it already has the proper wire size, (which is something there is no way for us to tell with the information you have given us).

**jwelectric** · 05-07-2011, 08:37 AM

10/3 with ground and a 30 amp breaker as has been pointed out

**eric3872** · 05-07-2011, 08:54 AM

Thanks for the reply. That is what I suspected. The 2nd electrician suggested their option without verifying the gauge. I am going to assume there is not a sufficient gauge running to the 20amp outlet until they can verify. Would you say the proposal from the first electrician, running a new line of a sufficient gauge back to a new 30 amp breaker at the panel is the way to go, or are there other concerns with this?

**jadnashua** · 05-07-2011, 02:08 PM

The only way to know if the existing wiring would support the dryer is to check it. IF it is of sufficient size, all you need to do is change the breaker and install a new plug. Otherwise, you can leave what's there and run a new wire to a new breaker (assuming there is room in the panel), or, you'll have to remove the existing breaker to install a new one. If the ends of the existing wire are properly managed, there's no problem with leaving it in place, but you should not branch off from one to the other.

**cacher_chick** · 05-07-2011, 03:16 PM

No one would have installed 10/3 with ground for a 20 amp A/C circuit unless it was "free" wire that they had laying around.

Unless it is a rare case, you will need new wiring, along with the breaker and receptacle.
It sounds to me that this is what was recommended by electrician #1.

hj · 05-07-2011, 03:18 PM

quote; Would you say the proposal from the first electrician, running a new line of a sufficient gauge back to a new 30 amp breaker at the panel is the way to go,

From the information you have given us, the first one's proposal may be the ONLY way to go, and if done correctly there would be NO downside to doing it that way.

hj · 05-08-2011, 01:20 PM

quote;But it is interesting that 12 gauge copper thhn has an ampacity of 40 at 90' C.....
When you look inside that dryer or stove, you will notice the wiring will be 12 gauge.

But you will also notice that it has an "asbestos" or similar covering on it. Even water heaters have #12 for 4500 watt elements, but you will also see that they are very short runs. The original circuit should NOT have needed 12/3 so the question might be irrelevent. 90 C. is 194 F which is a bit "warm" for a branch circuit.

**ballvalve** · 05-09-2011, 10:44 AM

That wiring in water heaters has no markings or indicators on them, and it seems most new stoves no longer have any "asbestos" coverings on them. The MFG'rs seem to be above the code.

**DonL** · 05-09-2011, 11:07 AM

Originally Posted by hj

quote;But it is interesting that 12 gauge copper thhn has an ampacity of 40 at 90' C.....
When you look inside that dryer or stove, you will notice the wiring will be 12 gauge.

But you will also notice that it has an "asbestos" or similar covering on it. Even water heaters have #12 for 4500 watt elements, but you will also see that they are very short runs. The original circuit should NOT have needed 12/3 so the question might be irrelevent. 90 C. is 194 F which is a bit "warm" for a branch circuit.

The Length of a conductor is a factor in feeding the device. If the voltage drop on any length of wire is not that much, With the rated load, The wire should not get hot, At all. No mater what gauge that is used. Unless it is getting heat from another source , like in an oven.

DonL.

P.S. As far as I know Most High temp Wire insulation is now made of Teflon, Or equal. And is plenum rated.

**jwelectric** · 05-09-2011, 02:09 PM

Wire comes in all type of heat ranges not just 60, 75, and 90 degree

**Speedy Petey** · 05-10-2011, 03:47 AM

Originally Posted by cacher_chick

Electrician #1 sounds like he is on the right track.

...and #2 is a complete hack fool.

Actually, #1 is not really on track. "Replacing" the wire and breaker make absolutely NO sense at ALL. Simply to use the existing box location???

A) I guarantee you the box would be too small.
B) WHY remove a perfectly good existing dedicated circuit???

Just have someone run a new 10/3 dryer circuit to the location of the dryer.

hj · 05-10-2011, 10:25 AM

quote; "Replacing" the wire and breaker make absolutely NO sense at ALL. Simply to use the existing box location???

That might have been the poster's description. The electrician would have meant a complete new circuit, although he might have had to use the original one's circuit breaker location if there were no suitable ones for his new breaker.