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I am not getting 120 @ my hot to neutral in my dryer receptacle For my dryer outlet h1-h2 =240, h1 -n <40 , h2-n <20 does this mean that i have no ground at the box?

  • No ground? Wouldn't that just mean that the neutral isn't connected? You didn't show that you tested the ground. – JPhi1618 Nov 2 '17 at 18:31
  • Do you have 3-hole receptacle and plug for this dryer or a 4-hole? – Jim Stewart Nov 2 '17 at 18:35
  • You have an open neutral. The hot lines are reading 240V (phase to phase) . So perhaps the box is defective and you are not able to get a probe on the neutral or there is some other issue with the neutral. – Ken Nov 4 '17 at 9:18
  • Measure between your dryer chassis and each phase - be careful not to touch anything .. if you measure 240V .. unplug the dryer .. fix receptacle - if you have 4 wires to receptacle (but only a 3 prong receptacle change it to a 4 wire style and your dryer cord the same. Much safer.. – Ken Nov 4 '17 at 9:26
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With no 120 v reading the grounded and or grounding lugs going to a main panel are open. This happens at the outlet quite frequently. I mentioned both because it was not stated if it was a 3 or 4 wire.

  • Ed, are you suggesting that the open connection is at the receptacle or is it inside the panel? Should the original poster pull out the receptacle and check that first? – Jim Stewart Nov 2 '17 at 18:48
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    I did say outlet that is more common than the panel because of the stress on the wires when stuffing back in the box, rare to have neutral or ground come out in a panel bus. I worded it that way because some are getting hung up on "proper terms". – Ed Beal Nov 2 '17 at 18:56
  • Agreed it sounds like the neutral came loose in the receptacle. Might be a good idea to check all wires on both ends though. – ArchonOSX Nov 2 '17 at 19:48
  • Will a dryer work with no functioning neutral? – Jim Stewart Nov 2 '17 at 21:45
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    Usually the drum motor is 120 v and the heating elements are 240 so the drum would not turn – Ed Beal Nov 2 '17 at 22:12
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Do Not Plug The Dryer In!

This is a dangerous condition if you have the obsolete 3-prong dryer plug (called NEMA 10-30). It will electrify the chassis of the dryer near 120V, while the chassis of the nearby washing machine is grounded, as well as slop sink valves, light switch plates, etc.

This is because when NFPA (authors of the electrical code) started requiring grounds (thus NEMA 14 on dryers), they allowed grandfathering of the old NEMA 10 receptacles, and officially sanctioned getting ground by bootlegging it from neutral. This is not safe, because now instead of the chassis floating, now the chassis is tied to neutral. A neutral break means the 120V parts of the dryer are trying to return 120V to source, via neutral, there's no path, so the appliance side of the neutral break is "pulled up" to 120V.

NEMA 10 was outlawed in the, when, 80s? But what happens in the real world is this:

  • Susan has an older house with a NEMA 10 receptacle
  • Susan buys a new dryer with a NEMA 14 plug, and installers change the plug to NEMA 10
  • later, Susan sells this dryer on Craigslist
  • Jim has a newer house with proper NEMA 14 receptacle
  • Jim buys Susan's dryer, finds NEMA 10 cord, changes socket to NEMA 10
  • Karen buys Jim's house, changes her modern dryer plug to NEMA 10
  • Jim's new house has NEMA 14, he changes to NEMA 10 again

Thus, NEMA 10 spreads like a virus.

Seize the moment. Don't even bother trying to troubleshoot your problem, just pull some 10/3 cable and upgrade to NEMA 14 and bedone with it!

  • I guess replacing the 3 wire outlet with a new 3 wire outlet is still with in code. Now the issue is because op has an open neutral - op has 120v flowing through his chassis , if op were to measure dryer chassis to phase the measurement might be 240v. – Ken Nov 4 '17 at 9:22
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    @Ken Yes, that's why Home Depot still sells NEMA 10 sockets. Barely legal, but a bad idea. The measurement to phase you discuss will only occur if the dryer is turned on (or has a 24-7 vampire load). – Harper Nov 4 '17 at 17:35
  • @Ken the maximum voltage to ground in a 240 v system is 120 v. If it is a 3 wire system that the grounded or grounding conductor has opened the only possible voltage would be 120 as Harper points out the vampire load is a 120 v circuit in the dryer used for the control circuit if the dryer uses 120 v control. – Ed Beal Nov 5 '17 at 15:00
  • @EdBeal read my comment again - you will see I mention chassis to phase if your neutral / ground is OPEN as the case with the op. You have a phase flowing through a motor winding to the chassis - like a direct wire Chassis is now one phase - and as Harper pointed out - the dryer must be on. Measuring from the chassis at this point to other phase will yield the full 240V. Remember the op has an open neutral. Now if you were measuring simply ground to phase or neutral to phase then yes 120V is the reading as long as it is not a hi leg (aka stinger) - which in a home in the USA is very rare. – Ken Nov 6 '17 at 18:48
  • Ken is right, in a NEMA 10 installation, a broken neutral means the chassis floats up to the 120V potential of one leg, and therefore 240V from the other leg. That's one way to test insulation! – Harper Nov 6 '17 at 19:02

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