Hi! Kiln parts/wiring questions

[AMVS]

Hello! Just came across this forum while researching the dilemma that is my kiln, and have had so many of my questions answered! 

I apologize in advance for not knowing proper electrical terminology- I’ll try my best with the names! 

I bought a used kiln, and it’s been one mystery after another. It’s a Blue Diamond (appears to be out of business) 24 amp. I gave info to the electrician to have it wired. They installed an 8 gauge wire to a 60 amp breaker (I think -will add photo) and a plug that I believe is called a 30 - I forgot the name. Attaching photo for that, too. The electrician left and I went down excitedly to plug in my new kiln and no cigar. Plug didn’t fit. Electrician came back and then saw the kiln sitter and said the whole thing needs to be redone and paid for a second time. Six gauge wire, new outlet to accommodate the “50” plug that was on my kiln. No…He didn’t look at the plug for which he was installing an outlet. 
 

I called a contact who works at a kiln company and she said NOPE, go by 24 amps, leave the 30 amp outlet (if that’s what it’s called) in the wall and cut off the 50 amp plug on my kiln and replace with a 30 amp plug from Home Depot…no big deal. No $600 (plus the original electrician bill of $500), and my kiln will run. I hadn’t discovered the 60 amp breaker at the time I spoke to her, so didn’t get advice on that. 
 

Do I need to replace the wire that goes into the kiln? Home Depot only had the actual plug, no plug attached to a wire. The wire i have was for a 50 amp plug, and I don’t know if I’m messing things up by using it with a 30 amp plug at the end of it. 
 

Final question, I also read that the 60 amp breaker the electrician wired the kiln into is probably excessive. Perhaps he did that because what I had available/unused in my breaker box (less than 2 years old and 100% sure there’s nothing wired in without labels) were two 20s and a 15. 
 

Please help. I feel like giving up at this point. 
 

adding photos in separate post. 

[AMVS]

[AMVS]

[AMVS]

[AMVS]

[AMVS]

[Dick White]

While waiting for your pictures, a kiln must be on a circuit that is 125% of the amperage of the kiln. Yours is 24 amps, so a 30 amp circuit is needed. The 8 ga. wire is more than enough. Leave it alone.

Your kiln had a 50 amp plug. This is probably just a convenient coincidence, as that is what larger kilns use, so perhaps they just built them all with the same power cord, less inventory to keep on hand in the factory. It doesn't need to be 50, but that's what was there. You've already cut it off, so you are stuck with that. It would have been easier to change the outlet on the wall for one that fits the plug, but you are where you are so put the plug on the power cord.

Your picture of the circuit breaker for the kiln is cut off, can't see the numbers on it. Note that on 240V double pole breakers, the number on the handle is for each side of the circuit, but they do not add together, i.e, if the numbers are both 30, it is 30, not 30+30=60. However, If it is truly a 60A breaker (both numbers are 60), that is dangerous. The kiln only needs 30, the 8 ga. wire is only good for 40, but the breaker won't blow until a 60A error occurs, at which time the kiln will already be fried and the wiring on fire (that's a bit of an exaggeration, but don't have a larger breaker than the wire can handle or significantly larger than the kiln draws even if the wire is ok at the higher amperage). However, it is ok to have a smaller breaker than the wire size, just not the other way. So, change that breaker to a 30A and your kiln will be good to go.

[neilestrick]

Many kiln companies use 50 amp power cords on their kilns because that is the largest size cord that is used on kilns, and they only want to stock one size of power cord. Being larger than  is needed isn't a big deal.

Electrical code requires that kilns are on a breaker that is 25% greater than the actual amperage draw of the kiln. So you 24 amp kiln should be on a 30 amp breaker. The 6 gauge wire that was run may or may not fit in a 30 amp breaker, though. If it won't fit, code also says that it can be a breaker that is up to 50% greater, so it could be on a 40 amp breaker and still be up to code, and that should fit the 6 gauge wire no problem.

As long as the power cord, plug, and outlet are are rated for at least the size of the breaker then you're safe. It's all about the amperage. Your cord has wires that can handle 50 amps. The 6 gauge wire in the wall can handle 60 amps. You just need a breaker that is the correct size for the kiln (30 amp ideally, 40 if the wires won't fit), and a plug and outlet that are rated for at least as much as the breaker.

Your electrician probably looked at the Kiln Sitter instead of the serial plate. Sitters are rated for up to 50 amps, so they say '50 amps' on them, but that has nothing to do with the actual amperage draw of the kiln.

The kiln is is beautiful condition. Blue Diamond made nice kilns. If you need elements, go to Euclids.com

[AMVS]

I realized the breaker photo was cut off after the fact, apologies for the confusion on that. yes, you're right, it's a 30 and a 30 NOT a 60 and a 60. Whew! Good news! 

I agree...should have left the power cord. I was all worked up at that point and had access to wire cutters, and here we are. 

[AMVS]

Neil, thank you for the heads up on Euclids. I'll check them out. 

There's actually 8 gauge wire in the ceiling, but when the electrician saw the kiln sitter (like you said) he wanted to come back and rewire with 6 gauge. It sounds like the 8 will be fine for this kiln, thankfully. 

To be honest, I'm going to have to read your and Dick's posts through several times before I feel like I really "get it." Part of it is that electrical is so over my head, and part is brain burnout from freaking out all day because I thought $1500 went down the tube. 

Thank you both for your replies. You brought some hope to a super stressed out lady. 

[Mark C.]

Since you cut the plug off just rewire that new plug on the end of cord or have someone who knows how to do it. 

[AMVS]

I just rewired the plug and the kiln is on. There was  a faint electrical smell coming from the kiln, not the plug but it faded quickly. I’m assuming it’s because it probably hasn’t been turned on in 20 years, but please let me know if this is not normal for an old, out of use kiln that’s getting a second life. 

[neilestrick]

4 minutes ago, AMVS said:

I just rewired the plug and the kiln is on. There was  a faint electrical smell coming from the kiln, not the plug but it faded quickly. I’m assuming it’s because it probably hasn’t been turned on in 20 years, but please let me know if this is not normal for an old, out of use kiln that’s getting a second life. 

Yes, kilns smell when they've sat for a long time. Make sure the control boxes don't have dust and crud and spiderwebs and moues poop in them from sitting. Periodically feel the power cord and plug and make sure they're not heating up too much during the firing. Slightly warm is normal.

[AMVS]

Power cord is cool. Going to flip the breaker off and check the temp of the actual plug in another 10-15 min to make sure it’s not over hot.
 

This only has high, medium, and low settings, nothing more specific to temps/degrees. Any idea if certain elements are off during low or even medium and then turned on when switched to high? The lowest and the third elements remained off until I turned the knobs up. I don’t know if this was by design or because they were slower to come back to work. 

[neilestrick]

You won't get all the elements glowing unless it's on high.

Get yourself an inexpensive digital pyrometer and a heavy duty (8 gauge) type K thermocouple from Amazon and stick it in the spy hole to track temperature rise.

[JLay]

Hi I also have a Blue Diamond kiln, bought used, model 180, fired it up for the first time last week, the kiln did not fire up on the low setting but medium and high work fine, the sitter works and kiln did shut its self off. Wondering if this could be a switch problem, with the low setting, I have been trying to find anyone who may have an owners manual and wiring chart. Looking for any advice.

[Hulk]

Hi JLay,

I'm seeing an earlier request for the same info got no replies, however, in this thread a Forum member posted a diagram they had authored, same/similar kiln, about halfway down the first page

Kiln taking longer and longer to fire - Equipment Use and Repair - Ceramic Arts Daily Community

Perhaps that will help?

[neilestrick]

Is it a 4 position switch, where the dial clicks into position at lo, med, hi, off-  or does the dial turn smoothly from low to high?