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I recently had a dryer installed and it powered on, but wouldn't run. I was able to verify the voltage at 240v using a multimeter, but I'm not convinced that the outlet was wired properly. They are bringing a new dryer this weekend, but I want to test the outlet thoroughly prior to that time.

Is there a tester to verify it is grounded/wired properly? I've used testers for 120v outlets such as this one:

enter image description here

Is there something like this for 240v outlets?

or would something like this work?

enter image description here

  • Considering the device's functionality and output, I'm not convinced that home-made tester will function properly and it might just burn it up. – ChiefTwoPencils Feb 18 '15 at 20:30
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Given the 110V tester, I'll assume you are North American locale for this:

Look up your outlet type.

Test (using appropriate care) that you have 240V from the L1 to L2 (hots) (you presumably did this per your question, but make sure it's the correct terminals)

Test that you have 120V from each hot to neutral.

Test that you have 120V from each hot to ground.

Test that you have no, or very low, voltage from neutral to ground.

Only after testing that voltage from neutral to ground is 0 or very low, turn OFF the breaker for this dryer outlet and test for continuity (resistance, Ohms) between neutral and ground - there should be continuity - the resistance should be low.

No need for a "widget" if you have a meter and can use it safely.

If the wiring is done very poorly you COULD have a situation where the voltages look fine until you turn on the dryer - that would be from something like a high-resitance connection - the voltage at the plug would drop significantly when the dryer was plugged in and turned on. Careful (always use care and respect with electricity) testing with a dryer in place could verify this. There's not really a safe way to test for this without a dryer to plug in. That sort of thing would be more likely if the outlet was installed by an amateur (I'm not clear if it was in place and you don't know it's provenance, or if it was just installed - if just installed, call back whoever installed it to check it out.) This is especially true if the wire is aluminum.

  • I'm not sure on the provenance. I just purchased the house and the dryer sits in a room that was converted from a garage to a living space without permits, and much of the work is amateur, so I would suspect it was not a licensed electrician (also the outlet is mounted on the wall and is loose, so that is more evidence of it being amateur). I am going to secure it better, but wanted to verify it was wired properly before doing that. I am unsure as to the type of wire used. – MaQleod Feb 18 '15 at 19:51
  • That raises the odds on "bad aluminum connections" (or just bad connections, but Aluminum adds extra ways to get there) in my offsite analysis. Assess your comfort level and either get it checked by a real electrician or ask for more help. If you turn the breaker that controls it off you should be able to verify no voltage and then take the outlet apart to see what color the wires are, and perhaps post some pictures. If you are not comfortable opening up the main service panel (where the input wires are ALWAYS hot, even with the main breaker off), you probably should call an electrician. – Ecnerwal Feb 18 '15 at 20:30
  • Curious under what condition(s) would you ready any voltage across the grounded and grounding conductors at an outlet pulling no load; can you enlighten me? – ChiefTwoPencils Feb 18 '15 at 20:35
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    @ChiefTwoPencils The main case to beware of is gross miswiring where you'd find 120VAC. The other case would be improper (by current code) wiring where the dryer is not the only thing on the circuit, or when there is something funky with the ground and neutral wiring (high resistance or improper bonding, shared neutrals, etc.) causing the entire neutral buss or this one wire to float a little bit WRT ground. – Ecnerwal Feb 18 '15 at 20:49
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    Or improper conductor size, or mismatch between the current ratings of the receptacle, wiring and/or breaker (eg: 50A breaker on 14AWG wiring with a 30A receptacle). One of the terrible things about electrical is it can "work" (for years, even) while actually being very unsafe. – gregmac Feb 18 '15 at 21:38

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