old 3 wire dryer circuit

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Daja7

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Changed out an old split bus panel for customer. MCB outside new panel inside . Isolate neutral and ground bus.
This older home had a typical 3 wire SE cable for dryer. concentric conductor used as ground. ( bare)
Inspector said we had to move to the neutral bar and wrap in white tape. My objection was we are now removing the ground.
he said most new appliances are 240/120 and needs the neutral. Again i said I was not comfortable removing ground.
Customer say she can not afford to run whole new circuit for her 3 wire dryer. I alwasy like to be reasonable with inspectors and not go over their head.
any thoughts on was to convince?
 
it's not the time involved. I would be removing the ground. dryer not grounded.
Do not see anything in the code that could make that case.
 
Neutral and
480sparky said:
As it stands, you're sending the neutral current through the ground bar.
Click to expand...
it is a ground bonded to the dryer at the dryer. Panel neutral and and ground bars are isolated because first point of disconnect
is MCB outside. That is why you are required per code to separate them when this is the case.
 
Daja7 said:
Neutral and

it is a ground bonded to the dryer at the dryer. Panel neutral and and ground bars are isolated because first point of disconnect
is MCB outside. That is why you are required per code to separate them when this is the case.
Click to expand...

But right now all of the neutral current goes through the panel ground. Once it hits the ground bar in the panel, how does it make it's way to the service neutral?

Daja7 said:
No because it is an older dryer there is no neutral per se, factory bond.
Click to expand...

Oh, there's a neutral in the dryer. The motor is 120v. The control dial probably uses 120v as well.
 
Daja7 said:
No because it is an older dryer there is no neutral per se, factory bond.
Click to expand...
You are not changing the dryer bond at all. It is a legally bonded 'grounded conductor'. Taping it white does not change the current flow of the dryer. The braid always carried the motor load. It still will. Tape it up as he suggests and put it on the neutral bar. Not an EG bar.

We would have included a new 4 wire to replace the existing in the price of the change over.

eta:. I think he could have required the change to a 4 wire, and probably should have.
 
480sparky said:
But right now all of the neutral current goes through the panel ground. Once it hits the ground bar in the panel, how does it make it's way to the service neutral?



Oh, there's a neutral in the dryer. The motor is 120v. The control dial probably uses 120v as well.
Click to expand...
The panel ground is isolated from neutral bar. neutral is not bonded to panel. All of these older dryers
require to be grounded per manufacturers instruction. Ground is for personal safety.
 
It will still be grounded......... through the neutral. Any ground fault will travel through the braided conductor, to the neutral bar, and back to the transformer through the service neutral. If sufficient current flow occurs, the breaker/fuse will trip/blow.
 
ptonsparky said:
You are not changing the dryer bond at all. It is a legally bonded 'grounded conductor'. Taping it white does not change the current flow of the dryer. The braid always carried the motor load. It still will. Tape it up as he suggests and put it on the neutral bar. Not an EG bar.

We would have included a new 4 wire to replace the existing in the price of the change over.

eta:. I think he could have required the change to a 4 wire, and probably should have.
Click to expand...
Not here, existing can stay existing. I have been doing this for forty years and the first time it has come up.. Customer does not
Have the money for new circuit. being factory bonded you would have redundant conductors unless modifying the machine.
I would prefer both but not practice in this situation. Rather have the ground for safety given the choice.
 
On a 3-wire dryer install, the 3 wires are (2) hots and (1) neutral. There's no EGC, that's why the third wire belongs on the neutral bar.

If you read NEC 250.140 Exception (under 250 Part VI "Methods of Equipment Grounding") which applies to this install, you'll see the exception allows you to bond the frame of the dryer to the neutral (grounded) conductor. The inspector is being generous in allowing you to apply the exception to your situation, rather than making you run a new 4-wire circuit.

Cheers, Wayne
 
Philosophically, what is the different between the neutral and the EGC? They are interconnected at the service, so the only real difference is that the neutral carries current during normal operation, while the EGC only carries current during a ground fault (and the sizing rules are accordingly different).

On a 3-wire dryer install, there will be current on the third wire during normal operation, as the dryer has 120V loads in it. So that makes the third wire a neutral, rather than an EGC. 240.140 Exception allows you to use the neutral for bonding in this special case, rather than requiring an EGC. It's effectively an allowed bootleg ground, for this once case.

Cheers, Wayne

PS (Edit) If you had a 240V only dryer, then you wouldn't need a neutral, and you could use a NEMA 6-30 receptacle, and the third wire could be the proper EGC. But those are less common in the US, I think primarily European brands.
 
Similar to a bare neutral used to ground a meter socket done all the time. It is only allowed for ranges, cook tops and dryers for existing 3 wire circuits.

I live in a 40 unit condo built in the 80s. All the ranges and dryers are 3 wire. What if it was an old apartment building with 6 floors and all concealed wiring? The cost to make them all 4 wire would be outrageous.
 
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