Another note on 3 prong dryers

[dhalleron]

I've seen this connection done many times on 120 volt receptacles. I would never do it on any type of receptacle.

When I found this on a job for my first time I couldn't help but wonder. Even though it is wrong, is it really any different than using a 3 wire receptacle for a dryer from days gone by?

 

[mbrooke]

I've seen this connection done many times on 120 volt receptacles. I would never do it on any type of receptacle.

When I found this on a job for my first time I couldn't help but wonder. Even though it is wrong, is it really any different than using a 3 wire receptacle for a dryer from days gone by?

View attachment 10379

That set up even prior to 1996 wouldn't have been complaint even with a NEMA 10-30r. The neutral conductor cant be bare, it must be insulated. From the looks of it someone used 10-2NM with ground, a very common mistake but still not to code.

 

[xformer]

I've seen this connection done many times on 120 volt receptacles. I would never do it on any type of receptacle.

When I found this on a job for my first time I couldn't help but wonder. Even though it is wrong, is it really any different than using a 3 wire receptacle for a dryer from days gone by?

View attachment 10379

I cant speak for the "days gone by", but I am wondering if this is single phase 120V or single phase 240 volt? If its the Latter I woudl say that there are safety issues....

 

[dhalleron]

That set up even prior to 1996 wouldn't have been complaint even with a NEMA 10-30r. The neutral conductor cant be bare, it must be insulated. From the looks of it someone used 10-2NM with ground, a very common mistake but still not to code.

Yes it is wrong in more ways than one. I was even taught to use 10/2 with bare ground many years ago.

So if it was a 10/3 without ground, how much different is this and installing a jumper compared to using a 3 prong dryer outlet? Still wrong, but just as safe as the old way of doing it with 3 wires?

 

[dhalleron]

I cant speak for the "days gone by", but I am wondering if this is single phase 120V or single phase 240 volt? If its the Latter I woudl say that there are safety issues....

It's a house with no sub panel. 100 amp single phase 120/240 volts.

 

[xformer]

Yes it is wrong in more ways than one. I was even taught to use 10/2 with bare ground many years ago.

So if it was a 10/3 without ground, how much different is this and installing a jumper compared to using a 3 prong dryer outlet? Still wrong, but just as safe as the old way of doing it with 3 wires?

IMHO, with a 10/3 without ground, the fault current, if any would travel through the jumper to the grounded conductor back to the source. Since the grounding jumper is for Safety, I would say that the 10/3 would be the better choice since with the 10/2 the return current from normal operation tracks along a parallel path.

 

[mbrooke]

Yes it is wrong in more ways than one. I was even taught to use 10/2 with bare ground many years ago.

So if it was a 10/3 without ground, how much different is this and installing a jumper compared to using a 3 prong dryer outlet? Still wrong, but just as safe as the old way of doing it with 3 wires?

Don't feel bad, years ago I was taught the same and used 10-2 for dryer:ashamed1:.

If it was 10-3 I would say its not so bad. The neutral jumper is being moved from the dryer to the plug, which in theory is doable. However, one issue exists that the terminal may not be rated for more than 1 conductor. A loose connection could forum over time.

Using the neutral for grounding dryers and ranges was tolerated because 120 volt loads are only a small percentage of the conductors rating with fewer connections to fail between panel and appliance. However, comparing the two its no different than a 120 volt 15 or 20 amp bootleg. If the neutral breaks anywhere the case becomes live.

 

[Sierrasparky]

Ok so say this is existing: 10-3 w/G and is fed from a Sub panel. Built in the 1980's so code probably around the 1978 code if that was a year.

You are installing a new dryer. Do you change to a 4 prong or go with the old 3 prong and nuetral and ground tied at the dryer. The ground is laying in the outlet box.

 

[xformer]

Ok so say this is existing: 10-3 w/G and is fed from a Sub panel. Built in the 1980's so code probably around the 1978 code if that was a year.

You are installing a new dryer. Do you change to a 4 prong or go with the old 3 prong and nuetral and ground tied at the dryer. The ground is laying in the outlet box.

If I remember right, current code still allows the the neutral to ground pig tail, so IMHO, it doesn't really matter. But, If you want to avoid confusion and simplify things, i would go with the 4 prong, since the 3 prong are making a slow exit. See 250.140

 

[kwired]

Even though it is wrong, is it really any different than using a 3 wire receptacle for a dryer from days gone by?

View attachment 10379

Not really much different. You do have additional connection(s) to possibly fail. As far as using a single conductor for both grounded and grounding conductor - it electrically is the same. Code still wanted that conductor to be insulated even when 3 wire was the normal practice.

I cant speak for the "days gone by", but I am wondering if this is single phase 120V or single phase 240 volt? If its the Latter I woudl say that there are safety issues....

It is 120/240 as in both voltages are utilized for this particular circuit, and all three conductors can be carrying current.

Yes it is wrong in more ways than one. I was even taught to use 10/2 with bare ground many years ago.

So if it was a 10/3 without ground, how much different is this and installing a jumper compared to using a 3 prong dryer outlet? Still wrong, but just as safe as the old way of doing it with 3 wires?

How about people that don't remove the bonding jumper in the dryer when utilizing a 4 wire cord?

IMHO, with a 10/3 without ground, the fault current, if any would travel through the jumper to the grounded conductor back to the source. Since the grounding jumper is for Safety, I would say that the 10/3 would be the better choice since with the 10/2 the return current from normal operation tracks along a parallel path.

Having a 4th conductor for equipment grounding purposes only is the safest method. Whether 3 conductors has an insulated grounded conductor or not, it is still going to raise the voltage of the frame of the appliance to the same level as the voltage drop on the grounded conductor, because they are electrically connected together, and anything conductive that is in contact with that appliance or the so called "EGC" will be subjected to same voltage or will carry some neutral current if it is in contact with anything grounded.