1

I have a 220v tanning bed.

The bed has a 4ft cord bed plug; need to extend another 10 feet to reach 220v dryer outlet 220v dryer outlet.

The bed came with a homemade extension, but plug doesn't fit our outlet.

Homemade extension wire is 10 gauge; 15 feet long.

Is it safe to just replace the plug on the homemade extension with one that fits my outlet?

Thanks in advance!!

  • 5
    Besides evaluating the safety of the electrical extension you should also seriously evaluate the safety of using a tanning bed. Unless this is an application prescribed for a specific medical condition you should seriously consider discontinuing the use of such bed altogether. – Michael Karas Jan 24 '16 at 0:00
5

The only solution, is to install a code compliant grounding conductor, circuit breaker, and receptacle.

The circuit breaker is easy. Since you're going from 30 amperes down to 20, you can simply swap the 20 ampere breaker in. However, since you're changing it to a 20 ampere branch circuit, AFCI and/or GFCI protection may be required.

The receptacle is also easy. Just swap out the old receptacle for the new one.

Installing a code compliant grounding conductor may require pulling a new cable. Depending on the home, you might be able to find another way. Though without being on site, it's difficult to suggest a solution.

Once you have the proper circuit protection, wiring, and receptacle. Then you can buy an extension cord, and safely extend the reach of the cord.

If you end up having to pull new cable anyway, you might consider simply installing a new receptacle closer to the tanning bed.

5

The plug on the tanning bed is a 6-20P plug (250V 20 Amp), but the receptacle is a 10-30R (125/250V 30 Amp), so they aren't quite the same. The tanning bed expects 2 hots and a ground wire, but the outlet provides 2 hots and a neutral (which is almost, but not quite the same)

The "correct" way to do this would be to replace the dryer plug with a properly grounded 6-20R receptacle and replace the 30 Amp breaker in the panel with a 20 Amp. The only difficulty may be in finding a code compliant way to hook up the ground terminal of the 6-20R using existing wiring.

If the existing shared neutral/ground wire is bare or green, then you can use that as-is, just make sure that it's connected to the grounding busbar in the panel. (a main panel may have shared ground/neutral busbar(s), a subpanel will have separate busbars for ground and neutral and it is important for safety to terminate grounding conductors on the correct busbar). If the existing neutral wire is not already a green insulated or bare copper wire, you cannot re-use this wire as a ground even if you mark the wire as such. If the wires go through continuous metal conduit back to the panel, you may be able to use the conduit as ground through a self-grounding receptacle in the metal box, or a ground jumper from the conduit/box to the receptacle.

Once you have a grounded 6-20R receptacle to plug into, you can use an off-the-shelf 6-20R extension cord to extend it.

For something like a tanning bed where people (likely with damp sweaty skin) will definitely be in contact with it, I wouldn't cut corners on grounding and do it the right way.

There are 6-20R to 10-30R adapters available, but they are not safe or technically legal

  • 3
    Grounds are not neutrals, not in the slightest. It is easy to misconceive this as being equivalent from seeing them meet the same termination, but the same could be hastily said of Lincoln and Hitler. – Harper Jan 24 '16 at 18:24
  • @WolfHarper - Not in the slightest? What about the case of a 3 wire 10-30R where the neutral is bonded to the chassis of the appliance? Doesn't that neutral have at least a similarity to a grounding wire? – Johnny Jan 24 '16 at 19:15
  • 2
    @Johnny in that case, the neutral does obviously have a grounding function and of course the neutral is grounded both at the main service panel and on the utility pole. On the other hand, in that case, the neutral's purpose as a neutral is to provide a 120V potential (e.g. voltage) return path for gidgets and lights and stuff in the appliance that don't want to use the 240V potential between the hot conductors. I'm still trying to figure out which (neutral/grounded or grounding) is Hitler and which is Lincoln? – Craig Jan 24 '16 at 21:11
  • 2
    10-30R is archaic for just that reason. Neutral has one purpose, returning current. Ground has one purpose, an emergency current catcher in case of a problem with wiring or a device, any current flow is a ground fault. There should be megaohms of resistance between your neutral bus and your ground bus, notwithstanding the jumper we put there on purpose. One could put a ground-fault relay there instead, but it would have to trip the whole house (not knowing which circuit leaked) and the homeowner would just defeat it. GFCI's are a more workable solution. – Harper Jan 24 '16 at 23:57
  • 1
    @Johnny I believe we're tripping up on nomenclature. NEMA 10 provides absolutely ungrounded service - it is the split-phase equivalent to NEMA 1, 11 or 18. NEMA 10 cannot proffer ground in any way. "Shared neutral/ground" applied (past tense) to appliances, not outlets: an ugly compromise from the infancy of grounding, where appliance makers were allowed to bond chassis to neutral, believing protection from a hot-chassis fault was worth risking floating a neutral on heavy plugs on equipment that never moved. Calling it a ground was a fiction, which NFPA abolished in 1996. – Harper Jan 25 '16 at 20:02
-5

Check to make sure the breaker for this 10-30 is in a MAIN panel, and not a sub panel. If it's a main panel the case, then it is safe to adapt a 6-20P extension cable with a 10-30p replacement plug head. You won't have to modify the building this way, so don't worry about code. CLEARLY label the cable you make for this purpose.

If the panel is a subpanel then you will need to move the neutral conductor to the ground bus bar and yes, that violates code because the outlet is supposed to be able to supply ungrounded split-phase. So CLEARLY label the outlet, or take the opportunity to replace it with a 6-20 outlet and swap the breaker out with a 20-amp while you're at it because you must do so to protect the 20-amp outlet per code. Then use an off the shelf 6-20 extension.

  • 1
    Technically correct, but perhaps this isn't the forum to be advising DIYers to violate the electrical code, especially since they may not be likely to understand what a subpanel is vs a main service panel, or understand the distinctions between grounding and grounded conductors, or understand the requirement or the reasons why neutral and grounding conductors must be bonded together in a main panel, but isolated in a subpanel. – Craig Jan 24 '16 at 6:46
  • This forum is for adults who are interested in understanding their own DIY projects so thorougly they come to a group of others to ask and get advice. It's not my place to decide for someone else they are unqualified to think on their own and make their own decision; nor is it yours. I came up with two ways to do what he wanted. One did not enter the purview of code. The other was entirely compliant with code. "Bulldoze the house and pay a contractor to build a new one with exactly the outlet he needs in the place he needs it." is not a useful suggestion here. – Billy C. Jan 24 '16 at 7:15
  • Who said anything about bulldozing the house? – Craig Jan 24 '16 at 12:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.