220V Wiring Help

silver_pilate

silver_pilate

Joined
Oct 30, 2002
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I've got my HT oven set up running off of an old 220V 3 prong dryer cord/plug like this:

10623201.jpg


The shop I'm renting (and will be for a long while) is wired for a 220V 50 Amp plug that looks like this (sorry for the size):

DSCN3900-220Socket1.jpg


If I were to buy a plug to match this 4 prong outlet, how would I splice it to the old 3 prong cord? Oviously the two hots match up, but do I hook the third wire (neutral, I believe) up to the neutral of the 4 prong plug and leave the ground wire unattached? Or can I run a wire from the ground wire to the frame of the oven for an extra safety?

Thanks in advance.

--nathan
 
NO!!! YOu should have the breaker swapped out for a 30 amp or whatever your oven is designed to run on and have the outlet changed. Running 50 amps into a 20 or 30 amp device is bad for you. The wire is not big enough....FIRE, FIRE......heh, heh, heh, heh.:D What HT oven do you have? My 24 inch Paragon is factory wired for the oddball 220v 20a setup.
 
Yeah what jdm said. IF you if you somehow figure out how to wire the cord from your kiln into the current walls 50amp plug, i think there is a possibility you could fry your kiln and the place you're plugging the kiln into!
 
That's why I ask. Don't want to end up dead.

My oven is a home built. The kanthal elements run in series and draw 13 amps. It has been running off of a home dryer outlet (30 amp) and is fused internally.

Guess I'll talk to the landlord and have an electrician come out. So switch to a 30 Amp at the breaker and swap out plugs? If I'm not able to swap plugs, would I be able to switch breakers and then do the cord mod?

--nathan
 
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A circuit doesn't push amperage, it draws current based upon the device consuming power. All that you need to do is go to an electrical supply store and get yourself a new plug for the oven to plug into the outlet. You're perfectly fine with what you have, better in fact than most people. You can usually purchase a 3 foot cable that's got the right plug on one end and the bare wires on the other ready to be screwed into a device. for around $10 to 12 or so.

The danger comes when you use a device that draws more current than your wires are rated for. For example drawing 50 amps running a welder on a 30 amp circuit will generate heat in the smaller wires and is what can cause fires. Running on a larger circuit is not only benign, but recommended in many cases based upon the potential drop in line voltage due to distance. (example, my dryer outlet is 10 gage wire, but i use 8/3 for my extension cable after it)
 
Just a thought, not electrical advise, but there are many times that low amp draw appliances are plugged into outlets that could supply many times more amperage. It might be a good idea to confirm that your oven is correctly fused. And, from what I've seen, the third line on a 220v cord was connected to the ground lug.

Good luck with it, Craig
 
Nathan

Justin is right on with his comments.

All equipment should be self-protecting, with their own input fuses or breakers, like your oven. The way to calculate your internal fuse sizing is to take your maximum input current and add 25%. Then chose the next bigger standard size. This means that you should be using 20A fuses. Make sure they are rated for at least 240V or they won't really open when they blow.

Phil
 
I have 20 amp 240v rated barrel fuses in the controller box for the incoming lines as well as a separate fuse for the pid.

I guess I will have to open the box up on the oven because my memory is a bit fuzzy on exactly how its wired up. I will let you know if i have any more questions on how to wire it up.

Thanks for the help!

--Nathan
 
jdm61 said:
NO!!! YOu should have the breaker swapped out for a 30 amp or whatever your oven is designed to run on and have the outlet changed. Running 50 amps into a 20 or 30 amp device is bad for you. The wire is not big enough....FIRE, FIRE......heh, heh, heh, heh.:D What HT oven do you have? My 24 inch Paragon is factory wired for the oddball 220v 20a setup.
Click to expand...

This isn't right. If we couldn't plug devices in at less than rated power, we'd never be able to use something like a cellphone charger. The device you plug in draws the electricity. The breaker keeps you from drawing more power than the gauge of your wire is rated for. The fuse and protection circuitry in your device protect it from fire and electrical damage.

The 50A circuit itself is fine.

Sorry if I repeated what someone else said.
 
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