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Our dryer circuit has a 30A breaker and 50A receptacle. I've read that if any of this was new work, it would not meet current code. Example:

Can I connect 12 AWG wire to 10 AWG in a junction box?

When was this requirement codified?

April
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  • Are you ***sure*** it has a 50A receptacle? No dryer cord would ever be sold that is 50A, except maybe for commercial dryers in a laundramat. It would require a double failure of both the person who fit the receptacle choosing a very wrong receptacle, and the person who selected the dryer cord selecting a cord that is specifically not sold as a dryer cord. – Harper - Reinstate Monica Jun 01 '18 at 18:32
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    @Harper The previous homeowner could have installed a 50A receptacle, and new owners could have modified their dryer to suit the receptacle. It's not obvious to non-electrical folk, that different receptacle configurations have any meaning. – Tester101 Jun 01 '18 at 18:39
  • @Harper The brown plastic cover of the surface mount receptacle is embossed with 50A, UL and GE. It accepts plugs with three flat blades. Looks like this: https://i.ebayimg.com/images/g/aT8AAMXQW7VREb-y/s-l1600.jpg – April Jun 01 '18 at 18:40
  • @Tester101 We purchased the dryer new from an appliance store, and it was installed new by the store. We haven't modified it. – April Jun 01 '18 at 18:41
  • @April I was responding to Harper, explaining how this could have easily happened. The answer to your question, sort of, is... Not all electrical work is inspected (unfortunately). Replace the receptacle (or have it replaced by a professional), with the proper 30A receptacle. – Tester101 Jun 01 '18 at 18:43
  • Wow. That is a NEMA 10-50 alright. I remember throwing one away that was NOS in our inventory. True @Tester101, people often don't realize how easy it is to swap sockets. Given the dialogue in the other question I suspect this will be replaced anyway as part of other work. – Harper - Reinstate Monica Jun 01 '18 at 18:52
  • Not disputing the code issue, but if it is 30A dryer + 50A receptacle + 30A breaker then anything going wrong will still (appropriately) trip the breaker. Alternatively, if someone connected a 50A dryer (or welder or whatever) because they saw 50A receptacle and didn't know it was a 30A breaker then they will trip the breaker if they actually use 50A (or anything close) and again they are protected. The problem would be if they then say "50A receptacle, I'll replace the 30A breaker with 50A" because the wiring is probably only able to safely handle 30A - and THEN they have a BIG problem. – manassehkatz-Moving 2 Codidact Jun 01 '18 at 18:53
  • @Tester101 - *"Not all electrical work is inspected (unfortunately)."* - That is my interest here. Does the receptacle predate the NEC pairing requirement, or predate the city's code enforcement, or was it done without a required permit, or the inspector passed it anyway? And why didn't our pre-sale house inspector note it? – April Jun 01 '18 at 18:58
  • @Tester101 - From what I understand, I can't replace the receptacle with a 30A 3-prong. The new receptacle would need to meet current code and be a 30A 4-prong, which means I'd have to run new 4-wire from the panel to the new receptacle. – April Jun 01 '18 at 19:02
  • @manassehkatz You're correct, it's likely not dangerous as is. However, it makes it difficult to plug in the properly corded dryer. – Tester101 Jun 01 '18 at 19:06
  • @April You're correct, you will *technically* need a 4 prong receptacle. However, you should be able to simply install a properly sized grounding wire. – Tester101 Jun 01 '18 at 19:08
  • @Tester101 - There are obstacles and a significant distance to the panel or to any other suitable gauge conductor in the ground network. for example the central 30A AC circuit (unless I could put a ground clamp on the nearby cold water line, which correct me if I am wrong, is not ok to do). – April Jun 01 '18 at 19:11
  • @April Not all electrical work requires permits. As to why the home inspector didn't notice it, I have no answer to that. It's possible that he simply isn't experienced with electrical work. Keep in mind, most home inspectors are not trade professionals, and only have a broad understanding of the many trades involved in a home. – Tester101 Jun 01 '18 at 19:13
  • @Harper - also, it is unlikely, but it could have been originally been a 50 amp circuit, and the breaker downgraded to 30A when it started being used with a 30A dryer. – April Jun 01 '18 at 19:18
  • Exchanging a receptacle in the same location, either because of a broken or wrong receptacle, counts as maintenance and not "new work". One more thing: MC shell is not legal as a grounding path *today*, but at one time, it was. Yeah, a lot of home inspectors don't even realize a receptacle can be GFCI protected without having a test and reset button. – Harper - Reinstate Monica Jun 01 '18 at 19:21
  • @manassehkatz - the wiring turns out to be #8. See my edit to the other post https://diy.stackexchange.com/questions/139837/code-requirements-for-moving-3-prong-dryer-outlet?noredirect=1&lq=1 – April Jun 01 '18 at 22:29
  • @Harper -- I'm not sure if the armor on interlocked armor MC was ever a legal grounding path. old BX armor was until they added the bonding strip, and now it's not, but modern AC with the bonding strip is. MCI-A and MCC (MC-HL) armors are also legal for grounding, although you'd never find the last one in a house. – ThreePhaseEel Jun 01 '18 at 22:35
  • @April As far as I can tell (Harper & ThreePhaseEel will know instantly and with certainty) #8 can only go up to 40 A. Which means it should (as already planned anyway) only have a 30 A breaker and that the receptacle was simply the wrong type. – manassehkatz-Moving 2 Codidact Jun 01 '18 at 22:38
  • #8 can be breakered either 30A or 40A. The receptacle must still match the breaker, and no such thing as a 40A receptacle, so a 50A one must be used. The configuration would have been legal pre-1996 if the breaker had been 40A. Whoever changed it to a dryer circuit was correct to downbreaker to 30A. – Harper - Reinstate Monica Jun 01 '18 at 22:54
  • @Harper - I was commenting above my pay grade. – April Jun 01 '18 at 23:04
  • Sounds like "Yes, before 1996" is your answer? – Stanwood Jun 02 '18 at 03:07

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