Is a 10-2 conducutor acceptable for a Clothes Dryer?

[jxofaltrds]

There has been ranges and dryers that have neutral loads for long time. Ranges usually had at very least a 120 volt oven light, and maybe a 120 volt timer or clock. Dryers almost always have had 120 volt motor and 120 volt control timer, and sometimes a 120 volt light inside the drum. When you do run into one of these appliances with no neutral load they still have a neutral terminal on the main power block - I suppose partly because most of them will still have a 125/250 volt cord cap installed on them and that gives you a place to land the neutral even though it isn't needed.

The if new appliances require a neutral should they be required to be changed to a 4-wire system or be allowed to be connected to the 'grandfathered' 3-wire?

I fully understand that, very likely why I put 'NM' in my post.

I know that we used NM in the early 90's for dryers when I was a helper bee!

 

[kwired]

The if new appliances require a neutral should they be required to be changed to a 4-wire system or be allowed to be connected to the 'grandfathered' 3-wire?



I know that we used NM in the early 90's for dryers when I was a helper bee!

If the "grandfathered 3 wire" is already there you do not have to change it. See exception to 250.140, but I am sure you are aware of this, maybe you are asking >>if you have a two wire plus ground circuit (straight 250 volt) and now need a 3 wire (125/250 volt) with or without ground circuit. That is a little different situation, but is also pretty rare situation to run into (I think). If it is run with 10-2 with ground, I say a new circuit with proper conductors is needed. If it was fed with plain 10-3 (no ground) and switched to straight 250 receptacle at one time - I have no problem with switching it back to a 125/250 volt three wire receptacle, in fact that is technically more correct than having the straight 250 volt receptacle using a white conductor as the equipment grounding conductor. JMO.

 

[jxofaltrds]

If the "grandfathered 3 wire" is already there you do not have to change it. See exception to 250.140, but I am sure you are aware of this, maybe you are asking >>if you have a two wire plus ground circuit (straight 250 volt) and now need a 3 wire (125/250 volt) with or without ground circuit. That is a little different situation, but is also pretty rare situation to run into (I think). If it is run with 10-2 with ground, I say a new circuit with proper conductors is needed. If it was fed with plain 10-3 (no ground) and switched to straight 250 receptacle at one time - I have no problem with switching it back to a 125/250 volt three wire receptacle, in fact that is technically more correct than having the straight 250 volt receptacle using a white conductor as the equipment grounding conductor. JMO.

That's what I was asking!

 

[anothaparson]

Thank You

Thank You

I just want to thank you all for replying to my post. I just wanted to follow up with the changes I made. I replaced my initial installation which was a direct violation of A 250.140 with a 10-3 MC Cable. I appreciate you all guiding me with a complete understanding of the history of the neutral conductor and its importance on most 240V/208V dryers and ranges. Believe me when I say I will never forget the lesson learned. Some have questioned whether I?m a qualified individual in safe electrical practices and my answer is in the question that I posted yesterday even though I had to swallow my pride and admit to myself that I screwed up. My pride didn't stop me from making an ass out of myself and that it the first part of safety asking the question even if it sounds stupid in order to get the job done according to NEC which guidelines safety.

 

[jxofaltrds]

I just want to thank you all for replying to my post. I just wanted to follow up with the changes I made. I replaced my initial installation which was a direct violation of A 250.140 with a 10-3 MC Cable. I appreciate you all guiding me with a complete understanding of the history of the neutral conductor and its importance on most 240V/208V dryers and ranges. Believe me when I say I will never forget the lesson learned. Some have questioned whether I?m a qualified individual in safe electrical practices and my answer is in the question that I posted yesterday even though I had to swallow my pride and admit to myself that I screwed up. My pride didn't stop me from making an ass out of myself and that it the first part of safety asking the question even if it sounds stupid in order to get the job done according to NEC which guidelines safety.

Its tuff in here. Glad to see you stick it out!

 

[bmarks2]

10-2 for Dryer

10-2 for Dryer

Assuming your dryer is a typical normal dryer that you buy today, it requires 10/3 because the controls are 120VAC. The motor and heating unit is 240VAC. A hot water heater only needs 10/2 because it has no 120VAC controls. The thermostats are normally 240VAC.

 

[iwire]

Assuming your dryer is a typical normal dryer that you buy today, it requires 10/3 because the controls are 120VAC. The motor and heating unit is 240VAC. A hot water heater only needs 10/2 because it has no 120VAC controls. The thermostats are normally 240VAC.

I think you will find the motor is also 120 so that it will run fine with the dryer supplied with either 208 or 240 volts.

 

[goldstar]

FWIW, I had to replace an electric cook-top last week and the wiring was 8/2 NMC w/ ground. There was no way I would be able to install a 3-wire without doing extensive damage to the finished basement. Low and behold, the new unit came wired black-red-ground. No neutral. Now, if I were wiring a new house would I be required to run a neutral even if the specs on the cook-top required only an 8/2 RX cable ? I probably would anyway but the mfr. of this cook-top had digital displays built into the unit and he didn't require a neutral.

 

[kwired]

FWIW, I had to replace an electric cook-top last week and the wiring was 8/2 NMC w/ ground. There was no way I would be able to install a 3-wire without doing extensive damage to the finished basement. Low and behold, the new unit came wired black-red-ground. No neutral. Now, if I were wiring a new house would I be required to run a neutral even if the specs on the cook-top required only an 8/2 RX cable ? I probably would anyway but the mfr. of this cook-top had digital displays built into the unit and he didn't require a neutral.

It seems like not very often you run into a cooktop that requires a neutral, but an oven usually does need one. Many guys run three wire plus ground just to be covered either way. Wiring new house - if the cooktop ends up needing a neutral and you don't have one - you have a problem. There is no code that says you must run a neutral irregardless of what may be installed, until they decided we needed one at many switch locations more recently.

 

[goldstar]

There is no code that says you must run a neutral irregardless of what may be installed, until they decided we needed one at many switch locations more recently.

I hear ya. I think in new installations it's all switch locations unless I'm mistaken. That means you can't install a dead ended 3-way anymore. Line comes in one end and load out the other.

 

[kwired]

I hear ya. I think in new installations it's all switch locations unless I'm mistaken. That means you can't install a dead ended 3-way anymore. Line comes in one end and load out the other.

I really don't know what the intent was. I think it can be interpreted as meaning all switch locations, yet as worded it really can be interpreted to mean multiple switch locations may not apply.

It is clear that it only applies to switches that supply lighting loads that are on a circuit utilizing a grounded circuit conductor.

 

[goldstar]

It is clear that it only applies to switches that supply lighting loads that are on a circuit utilizing a grounded circuit conductor.

I believe you are correct.

 

[Rick Christopherson]

In my opinion 10/2 NM has never been code compliant to supply a dryer.

A 3 wire dryer requires 2 hots and a neutral, all must be insulated.

The neutral was (is) allowed to be used as the grounding means, not the other way around.

Bob is correct. This is a very common misconception with DIY'ers who believe that it is the grounding conductor that is also serving as the neutral, when in fact it is the other way around. It is the neutral that was/is permitted to be used as a chassis ground.

I'm not an expert on old-code cycles, but unless there was a time when the neutral could be uninsulated, 10-2 was never permitted.

The NEMA 10-30R is an ungrounded 3-pole (120/240) receptacle. The NEMA 14-30R is the grounded 3-pole receptacle.

 

[kwired]

Bob is correct. This is a very common misconception with DIY'ers who believe that it is the grounding conductor that is also serving as the neutral, when in fact it is the other way around. It is the neutral that was/is permitted to be used as a chassis ground.

I'm not an expert on old-code cycles, but unless there was a time when the neutral could be uninsulated, 10-2 was never permitted.

The NEMA 10-30R is an ungrounded 3-pole (120/240) receptacle. The NEMA 14-30R is the grounded 3-pole receptacle.
View attachment 7264 View attachment 7265

The neutral could have been / still can be uninsulated for existing installations, if it is part of a type SE cable.

 

[iwire]

The neutral could have been / still can be uninsulated for existing installations, if it is part of a type SE cable.

Very true.


Have you seen 10/2 SE cable used for this?

 

[kwired]

Very true.


Have you seen 10/2 SE cable used for this?

Not sure if I have but I have seen SE cable that small if that is what you are getting at. Most of what I have seen was used on outbuildings on farms for service entrance purposes, and was likely installed back in 1940's or 1950's.

Electric dryers may have been in existance back then but was not a common item in the farm house. Rural electrification act had not been that long ago and people were just happy to have electric lights. Wow people today would never have been able to survive in those times, what did they do without internet social sites:lol: