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I purchased a table saw that has a NEMA 6-15 plug. I have two outlets, one 14-50 and one 10-30. I was wondering what's involved with installing a new outlet that has a lower amperage and a different plug?

I can't seem to find any info online about this specific scenario. I've read that it's possible to install the new outlet and lower the amperage at the box, however I'm unsure if this is 100% accurate.

Any help would be useful.

Thanks!

Edit, adding photos: enter image description here

  • What is the space in question? The 7-50 makes me wonder in particular as that's a 277V outlet usually only seen in commercial/industrial spaces with 277Y/480 3-phase service. – ThreePhaseEel May 23 '17 at 3:09
  • It's in a detached garage. I know the previous owners had an RV. Not sure if that's relevant. I'm going based on diagrams I've seen. I can post pictures if that's helpful. – Justin Warner May 23 '17 at 4:36
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    Please post pictures, yes... – ThreePhaseEel May 23 '17 at 11:36
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    Either it's not really a NEMA 7, or the homeowner was using it inappropriately. Are you sure it goes where you want? – Harper May 23 '17 at 15:25
  • @Harper, it is a NEMA 10-30. I read it incorrectly yesterday. Thanks for the sanity check. – Justin Warner May 24 '17 at 2:58
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You will need 3 wires.

  • A ground wire that is bare, green, or yellow/green striped.
  • Two other wires that you can distinguish from all other wires. You do not need to distinguish them from each other. They can't be any of the ground colors.
  • any other wires, cap them off.
  • if any of the two wires are white or gray, you must mark both ends with black tape.

What I mean by that is if your colors are black-black-white-bare, you must use the black-black as your conductors, bare as ground, and cap the white. You don't need to care which black is which on a NEMA 6 or 14.

Because you are using a 15A receptacle, you must get a 15 or 20 amp 2-pole breaker for your panel and fit it. Your two wires go on that. Ground to the ground bus, of course.

Then fit a NEMA 6-15 receptacle. You can use as many 6-15 receptacles as you want on the circuit, and they often come in a duplex. Also get the correct cover plate for your box. (If your breaker is 20A, you must use a minimum of two 6-15 receptacles, so get that duplex!)

enter image description here

Good chance the wires won't fit on the terminals. Get 8 inch lengths of copper 14AWG wires (12 AWG wires if a 20A breaker) and pigtail. You can use wire nuts or Alumiconns. If any wires are aluminum, definitely use Alumiconns. Aluminum wire is fine for large wires 4AWG and up, just terminate them properly.

Due to the 15/20 exception, you can use a 20A breaker instead. However: a) all your wires must be at least 12 AWG, including your pigtails. And b) you must either use NEMA 6-20 receptacle(s), or more than one 6-15, e.g. that duplex. 6-15 plugs will work in 6-20 receptacles.

What to do with that NEMA 10-30

NEMA 10 is bad news - it is the "death socket". It harkens back to the age before grounds, and provides two hots and a neutral. Sadly NFPA compromised with appliance manufacturers to allow them to ground the appliance to the neutral. Any trouble with your neutral wire will "float" the neutral at near 120V, and that electrifies the chassis. You should smash the 10-30 to smithereens and burn the pieces... and convert it to NEMA 14-30 (or anything else with a ground) ASAP.

But good news for you. First, you are allowed to retrofit grounds. You don't have to go all the way back to the panel, just to any nearby ground which is large enough (and comes out of the same panel). And look! Right next to the 10-30 is a 14-50 with a ground! That was easy.

Sometimes NEMA 10 circuits use cables with neutral carried as a bare wire wrapped around the two main conductors like a net. You're grandfathered! and can still use that as a neutral, make sure to wrap it with insulation so it can't contact the ground wire or box. Or you can sacrifice your grandfathering and use it as a ground for a NEMA 6. Your call.

  • Thanks for all the good information Harper. Really appreciate the thorough response. This is seeming to be more out of my comfort zone than I thought previously and have hired someone to take a look at it in the coming week and if the price is good and they bring up some of what you've mentioned above, then I'll probably go with them. I've learned a good bit here and through searching online for help. Thanks again! – Justin Warner May 29 '17 at 14:48
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Other than the comments above. Changing from a 50A circuit to a 15A circuit can be done. The problem lies with the size of the wire which could either be a #6 or a #8. It doesn't really fit in a 15A receptacle and a standard 15A breaker will only hold a #8 or smaller. So you will have to do some pigtailing to make things work. Other than that there is no code problem to reducing an amperage on a larger current carrying conductor.

If this is in a workshop you might consider installing a small subpanel on one of the 50A circuits and then you can install your saw on a 15A breaker and it would also give some ability to add other equipment later.

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You can also build an adapter cord. Screw type plugs and receptacles are readily available for each of NEMA 14-50 and NEMA 6-15. That and a short piece of cord and you're done.

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