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Old 11-08-2012, 07:51 AM   #1
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Dryer wiring


Well, my wife wants a new dryer and I'm doing legwork. Couple of questions.

Current dryer is three wire plug. I assumed this would be HOT-HOT-Neutral. After opening box and looking into breaker panel I think it is HOT HOT Ground currently, the ground wire is insulated though. The electrical panel feeding dryer is in attic and is a subpanel off main panel outside, this subpanel also powers HVAC system up there. It is a 240V only subpanel with no neutral wire. Is the current wiring for dryer incorrect and unsafe?

On to hooking up a newer model dryer: Is it possible to simply change to a 3 wire cord on new dryers and not worry about using a 4-wire plug (how would that be possible if newer models need 120V?). If a 4-wire plug is necessary, how do I get it considering panel is 240V only and has no neutral? Would a new run from main box be necessary that has HOT-HOT-Neutral-Ground? This option has to be my last resort because making that new run would be MAJOR work to get it to dryer location.

Excuse my ignorance about this, I am a cave man really and just doing the legwork and informing myself before I call in a professional to do the actual work. Thanks!

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Old 11-08-2012, 08:22 AM   #2
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Dryer wiring


If your dryer is wired from a 240 volt panel only it has been wrong for a long time. For this to work they are using the ground as a current carrying conductor and potentially putting voltage on the metal parts like the panel enclosure itself. This creates a serious shock hazard.

Older installations used the neutral and ground bonded together. Newer standards call for a 4 wire setup with the neutrals and grounding separate.

The proper way to do this is to install a 4 wire circuit from your main panel and install a 4 prong receptacle.

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Old 11-09-2012, 03:57 PM   #3
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Dryer wiring


Thanks Jim. I kind of suspected the current set-up was incorrect. I have no room left in main panel for a new circuit. If I can somehow get this 240V subpanel to work it would be the ideal situation, any ideas to make that work? Would it be possible to make a run from the ground/neutral in the main panel to this sub-panel and install an isolated neutral block in subpanel?
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Old 11-09-2012, 04:27 PM   #4
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Dryer wiring


You would need to install a larger 4 wire feeder to the subpanel sized for the current load plus the dryer load.
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Old 11-09-2012, 05:50 PM   #5
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Dryer wiring


If it is Black, Red, White, there is no ground. Can you post pictures of the wiring for that circuit in the power panel, and also can post the wiring on the dryer if you wish.
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Old 11-09-2012, 10:37 PM   #6
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Dryer wiring


I'm posting the code requiements to continue to use your present/existing dryer branch circuit. Why are you saying it is H-H ground ? The dryer is 120/240 volt if it isn't a gas model. It would be unusual for a panel to be without a neutral bar set on insulated standoffs. Got any pictures of this sub-panel?

250.140 Frames of Ranges and Clothes Dryers.
Frames
of electric ranges, wall-mounted ovens, counter-mounted
cooking units, clothes dryers, and outlet or junction boxes
that are part of the circuit for these appliances shall be
connected to the equipment grounding conductor in the
manner specified by 250.134 or 250.138.

Exception: For existing branch-circuit installations only
where an equipment grounding conductor is not present in
the outlet or junction box, the frames of electric ranges,
wall-mounted ovens, counter-mounted cooking units,
clothes dryers, and outlet or junction boxes that are part of
the circuit for these appliances shall be permitted to be
connected to the grounded circuit conductor if all the following
conditions are met.
(1) The supply circuit is 120/240-volt, single-phase,
3-wire; or 208Y/120-volt derived from a 3-phase,
4-wire, wye-connected system.
(2) The grounded conductor is not smaller than 10 AWG
copper or 8 AWG aluminum.
(3) The grounded conductor is insulated, or the grounded
conductor is uninsulated and part of a Type SE serviceentrance
cable and the branch circuit originates at the
service equipment.
(4) Grounding contacts of receptacles furnished as part of
the equipment are bonded to the equipment.
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Old 11-10-2012, 07:43 AM   #7
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Dryer wiring


The subpanel is is fed with a cable that consists of two very large wires and many bare grounding wires bundled together. It is an old subpanel in the attic that has two 65amp double pole breakers for two seperate HVACS and one 30 Amp breaker for the existing 3 wire dryer connection. There is definitely no neutral in this box.

I actually had an electrician look at box yesterday afternoon and he told me as the box exists now, everything is fine. Not up to current code, but acceptable. He told me that it would be possible to run a new 4 wire plug for the dryer utilizing the existing ground connection for the bare wire and neutral connection, but that he couldn't do it. I am so confused.
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Old 11-10-2012, 09:56 AM   #8
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Dryer wiring


It is not that he could not do it, it is that he would not do it.
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Old 11-10-2012, 10:07 AM   #9
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Dryer wiring


Because doing that would not meet current code requirements or because it is unsafe/wrong? I assume because it would not meet current code requirements or he wouldn't have said it was possible. Hypothetical: If what he had seen existing was a 4-wire circuit consisting of a 4-wire dryer plug, which had two hots from 30 amp breaker, one insulated neutral connected to ground bar, and one bare copper also connected to ground bar in sub panel, keeping in minf there is no neutral feed in subpanel, would that of been acceptable for old work, but not possible now?

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