I recently bought an older house, and I have been finding problems with the wiring in the breezeway and garage that was added on in the 80’s. It appears to have been a lot of DIY work that never got inspected properly. The most recent one I have found is with the dryer receptacle. This is a 10-30R (3-wire) receptacle fed from a subpanel. I know that this is not allowed by 2002 NEC, but was the 3-wire receptacle ever allowed when fed from a subpanel? I thought it was only allowed when fed from the main panel, since neutral and ground are bonded together there. I’m just wondering if this may have been allowed by code when it was installed or if it is another example of incorrect wiring. I plan to replace it with a 14-30R, since the cable has 3 conductors plus the ground.
"but was the 3-wire receptacle ever allowed when fed from a subpanel? I thought it was only allowed when fed from the main panel"
3-wire receptacles (i.e. using the neutral to ground dryer frames) was permitted up until 1996 (?); they were permitted to originate in any panel as long as the neutral was insulated.
Quite freguently SE cable was used to wire up stoves, ovens, dryers. Some of this cable did not have an insulated grounded (neutral) conductor. You were not permitted to use this type cable inside a house unless: you were feeding stoves, ovens, dryers and the circuit originated in the service.
See 1979 - 250-60(C) & 338-3(b)
Re: Dryer receptacles - was this ever allowed?#91751 02/03/0506:33 PM02/03/0506:33 PM
this was common, look at 250.140 (3) in the 2002 NEC applies to existing ranges & dryers, if the grounded conductor is uninsulated it must originate at the service equipment, and also look at 250.42 (B) exception #1 permits load side grounding, on existing ranges & dryers,
Re: Dryer receptacles - was this ever allowed?#91753 02/06/0510:39 AM02/06/0510:39 AM
If the neutral has to be insulated from a subpanel, wouldn't there always be a separate grounding conductor in the cable, so you'd always end up running a total of 4 conductors from the subpanel? Since you'd always have the separate neutral and ground conductors, the only real reason to put a 3-wire receptacle fed from a subpanel would be to avoid changing the appliance cord, which I assume was the reason in this case.
Re: Dryer receptacles - was this ever allowed?#91756 02/07/0501:26 PM02/07/0501:26 PM
Long ago I asked why you would run 10-3/wg to a 3 prong dryer outlet and the answer was that since the 3d wire is identified as a groundED conductor <some AHJs said> it had to be white, even tho it was also used as a groundING conductor. They usually attached the bare wire to the backstrap of the receptacle and the white to the ground contact. Once "the war was over" it is easy to go to the 4 pronger.