Dryer Bonding Question

[TNGuy81]

Hey to all and I apologize if this has already been asked and I am sure it has. I thought I had a pretty good grasp on bonding and grounding but here lately im questioning that. Anyway.

I have a old home with a 4 prong dryer receptacle in it and a old dryer that had a 3 prong whip on it. I switched the whip out to a 4 wire and made it up and noticed the 4 prong receptacle had only 10/3 (no ground) to it. I am aware this is not code but I am renting the place and it is what it is. I wired the 4 wire wipe up and disconnected the bonding jumper then just attached the ground wire to the frame. Was this the right thing to do? The fuse box is bonded at the main and I thought this was the safest way to do this. I dont want the neutral back feeding and someone getting shocked on the frame of the dryer. So its really only got hot/hot/neutral... but its bonded at the panel so the neutral serves as a ground also correct? Or do I need to put the bonding jumper back on the dryer??

Thanks in advance

 

[George Stolz]

By isolating the ground, you have created a shock hazard. If the ungrounded conductors inside the dryer come into contact with the frame of the dryer, then you have no effective ground fault current path to cause the breaker to open and clear the fault.

You should replace the receptacle, and leave the whip as it was.

You need to read this and watch the powerpoint demonstration.

 

[TNGuy81]

By isolating the ground, you have created a shock hazard. If the ungrounded conductors inside the dryer come into contact with the frame of the dryer, then you have no effective ground fault current path to cause the breaker to open and clear the fault.

You should replace the receptacle, and leave the whip as it was.

You need to read this and watch the powerpoint demonstration.

But would the neutral not serve as a ground here? The romex does not have a ground in it and its already bonded at the panel. My concern has by bonding the dryer it it could back feed through the frame creating a shock hazard. This is why I isolated it. Ill read the link when I get back from work thanks for the answer.

 

[TNGuy81]

Ok I re-read what you said and that makes sense, though isnt there a risk of shock it you were touching the dryer when it shorted out?

 

[LarryFine]

Ok I re-read what you said and that makes sense, though isnt there a risk of shock it you were touching the dryer when it shorted out?

Kinda-sorta, which is why the move to 4-wire supplies for major appliances was made, and we never used the neutral for grounding otherwise.

The insulated neutral in the non-grounded cable was done correctly. Whoever replaced the original receptacle with a 4-wire is the one who erred.

As stated above, the correct fix is the 3-wire receptacle and cordset, and replace the bonding jumper between the neutral and the dryer case.

 

[George Stolz]

Ok I re-read what you said and that makes sense, though isnt there a risk of shock it you were touching the dryer when it shorted out?

The goal is to get the breaker to trip as soon as there is a ground fault. With no equipment grounding conductor at the receptacle, and the dryer's frame connected to that nothing, then there is nothing to complete the other half of the circuit to get the breaker to trip.

 

[Dennis Alwon]

Suppose as George mentioned, the hot conductor for some reason comes in contact with the frame of the dryer. Now, those nice tenants reach over and touch a ground- perhaps the washer, or something, and then touches the dryer. Ouch..... you don't want that even if they aren't paying the rent. :grin:

 

[TNGuy81]

ok that makes sense to me now and I understand. Sounds like the right thing to do is to just run a new circuit 10/3 with ground, keep the 4 prong recp, and the whip. Then remove the bonding jumper because they will both be isolated. Its only like a 20ft run or less. The dryer is right next to the panel. Or if I dont replace the wire keep it how it is and just keep the jumper in there.

The fault is on the guy who just changed out the receptacle without changing the wire (landlords crew... .. .)for it would "appear" to be up to code. They did the same thing with my receptacles. Old 2 wire BX with 3 prong receptacles in there, zero ground.

Thanks for all the info.

P.S. The thumb down was for my landlord, not the post. I thought it would place it after a sentence but I see that it didnt.

 

[LarryFine]

Sounds like the right thing to do is to just run a new circuit 10/3 with ground, keep the 4 prong recp, and the whip. Then remove the bonding jumper because they will both be isolated.

You certainly can, but the "right" (as in "compliant") thing is to simply restore the 3-wire supply. Changing to a 4-wire supply is a step beyond, and certainly acceptable.

The fault is on the guy who just changed out the receptacle without changing the wire (landlords crew... .. .)for it would "appear" to be up to code.

My guess is a dryer that came with a 4-wire cord, which should have been changed to match the existing 3-wire circuit (and the jumper installed.)

They did the same thing with my receptacles. Old 2 wire BX with 3 prong receptacles in there, zero ground.

The BX may well act as the grounding conductor.

 

[TNGuy81]

My mistake its not BX cable. Its the old wire 12/2 with the mesh stuff on it. It doesn't look like MC cable or BX but there is no ground. Its really old wire. This house is from the 50s. Thanks

 

[SegDog]

from the '50s...????

from the '50s...????

I'm from the fifties, and I don't consider myself really old!

 

[LarryFine]

I'm from the fifties, and I don't consider myself really old!

We never do.

 

[LEO2854]

I'm from the fifties, and I don't consider myself really old!

We never do.

Who said were old:grin:

 

[nate roach]

first you said #10 wire, the you said #12 wire. so what is it?

 

[hurk27]

first you said #10 wire, the you said #12 wire. so what is it?

go back and re-read, 10 is on the 240 volt dryer, the 12 is on the 120 volt ungrounded receptacles.

A good point for having a good fault path for an electric dryer is its not to uncommon for the heater element to go to ground when it opens, the wire element is just that an open wire in a metal can, and if it ever burns open sometimes this wire element can fall down and touch this metal can, if there is no fault path it will liven up the whole dryer.

 

[TNGuy81]

old as in out dated wire/code.

 

[LEO2854]

My mistake its not BX cable. Its the old wire 12/2 with the mesh stuff on it. It doesn't look like MC cable or BX but there is no ground. Its really old wire. This house is from the 50s. Thanks

that mesh stuff is that cloth or metal

 

[TNGuy81]

its kinda both. Its really small strands of metal or the outside of the wire. They aren't all this way the others are just NM without a ground but a couple have this older wire. The panel is in good shape and so is the wire so I am not pressing this issue with the landlord. Yes a ground would be nice but we dont plan on living here too much longer anyway.