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Discussion Starter · #1 ·
I made a home made kiln and I am having trouble with the wiring. Take a look at the picture I attached -- it is a diagram of how I tried to wire the kiln to my 240 VAC range outlet.

I connected the two hot line wires together to get the 240 volts (I think this may be where I went wrong). From there I split the hot line to three infinite switches, each switch is wired to a single heating element (the switches are wired in parallel to get the 45 amps I need).

The instant that I plugged this in to my range outlet the range breaker and the breaker for the entire house blew. Also, one of the hot line prongs melted...all in a fraction of a second.

I just don't see any other way to connect the two 120 volt line wires to get my 240 volts. I am thinking the problem has to do with the line wires being out of phase...but I just don't know...I am a little out of my league here.

All of my wires, switches, and elements are of proper ratings to handle the loads I am trying to give them.

How should I wire my kiln so I don't blow my house up? Thanks!
 

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I=E/R
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Don't plug that thing in:no:
Are the elements 240 volt rated?
One side of each element will go to one blade on the plug and the other side of each element to the other blade. You will not be using the neutral.

You had a dead short from one hot to the other hot. You're lucky nothing happened other than a breaker.

Also, the ground will only be connected to the case of the kiln, all exposed metal parts should be grounded.
 

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Discussion Starter · #3 ·
Are the elements 240 volt rated?

Yes, the heating elements are rated for 240 volts; 15 amps each. The switches and wires are also rated as such.

Okay, so it sounds like I can take all three of the heating elements and wire them in parallel, one end into one of the hot lines and the other end into the other hot line? I will ground the steel case of the kiln.

I would have expected this type of wiring to cause a short, but that just shows you how much I know about this stuff.

I'll give it a try and let you know how it works.
 

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I=E/R
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If you would have connected only one blade to one side of the elements, your drawing shows a wire from each blade tied to all the elements, you would have been running the kiln at 120 volts but you would have had current flowing in the ground wire which is a no no.
 

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Discussion Starter · #6 ·
Wiring the elements in parallel -- with one end in one hot line, and the other end in the other hot line -- worked!

Thank you, helpful mystery stranger! :thumbup:
 

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A "Handy Husband"
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You have 3 15 elements for a total of 45 amps. What size is the breaker on your range receptacle? Hopefully 50 amps. Also your wiring from the receptacle to the kiln elements needs to be #6 AWG copper.

If your range receptacle and branch circuit wiring is only rated for 40 amps, you will be tripping the breaker. Not explosively the way you did with the dead short circuit, but it will trip. And don't increase the breaker size without verifying the amperacity of the branch circuit wiring.
 

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Discussion Starter · #9 ·
To answer the last few questions...the breaker is 60 amps and the wire is 6 guage copper to the infinite switches. From the switches to the elements is #12 MGT 1000 degree F high temp lead wire rated up to 600 V.

Despite my obviously stupid wiring error, I am actually quite capable.

Thanks all for the quick and accurate advice!
 

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Are the switches double pole? If not then only one of the hots goes to the switch. The other hot goes direct to the element.
 
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