Wiring a Paragon Kiln

[Mark C.]

How long is that #10 wire run-a few feet or longer??

Just for more info how long is the#8 wire run as well?

Many electricians are not aware that kilns need a 25% larger breaker which also means larger wire than whats on the name plate. Your kiln draws 30 amps and a 30 amp breaker may last week or a year but over time its will be toast.

Pleas post a bit more info on above questions

[Bill Kielb]

5 hours ago, DewDropDawn said:

Thank you for this info and your wiring installation concerns.  Let me provide more info.  We had 3 estimates from licensed/bonded electricians.  All suggested 8/3 wiring from Main to Studio Subpanel and 10/3 wiring from Subpanel 30 Amp to Kiln outlet.  So the Main panel has 60 Amp, which is wired to 8/3 going out to studio where kiln will be installed/used.  At the Studio subpanel, we have a 30 Amp to serve Kiln only.  The electrician (EE) who installed  60 Amp at Main and 8/3 wiring from Main to Studio checked model, distance of run and manufacturers breaker recommendation.  All are within range and EE noted great voltage reading at Studio subpanel with only slight drop when turned on.  EE not contracted to wire wall outlet to 10/3 wiring.   That's on me.   And since I ran into the previously outlined wiring configuration difference between new outlet and older model Kiln plug in, I asked for help.  

What do you think?

Thanks

Hmm, I’ll just say this from looking at your nameplate and description. The 30 amp kiln because it is a purely resistive load and can operate at full load (defined as continuous load) needs to be 125% of full load current. 30X1.25 = 37.5 Amps which means a 40 amp kiln breaker and # 8 wire for 75c roamex limited by terminal rating in the kiln.

The sub main breaker must be sized at 100% of non continuous load plus 125% of continuous load which might be 40 (Kiln) + 20 ( other loads) so 60 Amps Is probably fine but #8 on a 60 amp breaker doesn’t sound good. #6 generally gets you 55 Amps for roamex or underground burial stuff.

Definitely worth double checking in my view. I am not sure what spec they checked but when I look this up on the Paragon website this glass kiln requires a 40 amp breaker.  Interesting that when I look this up from the manufacture it comes out exactly as I would calculate it.

Only other thing left would be to have an idea of the distance of each run as I would strive to limit the voltage drop (calculated) to 1% rather than 3%. It’s hard to measure this accurately unless you are operating at full load for some time and the cable has heated up. Besides since your kiln was not wired with a plug it would have been hard to test voltage drop and even if it was hot wired temporarily I would let it run at full load for an hour to see how much drop will accumulate. None of this sizing for any of it seems correct, probably a good time to step back and double check.

 

[neilestrick]

Code requires that resistance heating appliances (kilns) be on a breaker that is 25% greater than the draw of the kiln, but not more than 50% more. So for your kiln that draws 30 amps, it would be on a 40 amp breaker minimum, 50 amp maximum. Ideally the 40. 

[Mark C.]

40 amp breaker is a #8 wire not a #10 as noted in above posts. 

[DewDropDawn]

16 feet between subpanel and kiln outlet.  Well, all the drywall and insulation just finished and the 3 electricians here think differently and now this could be a problem.  Thanks for all the info and heads up.  

[neilestrick]

National Electrical Code- 422.10- The branch-circuit rating for an appliance that is continuously loaded, other than a motor-operated appliance, shall not be less than 125 percent of the marked rating, or not less than 100 percent of the marked rating if the branch- circuit device and its assembly are listed for continuous loading at 100 percent of its rating.

If nothing else, they should defer to manufacturer's recommendations. The kiln may or may not function on a 30 amp circuit. It may flip it, especially if your voltage is running high, which is not uncommon. I've seen a lot of 48 amp kilns that will blow a 50 amp breaker. From a liability standpoint, not following manufacturer's guidelines or codes could cause trouble if there's ever a problem in the future, be it in dealing with insurance companies or lawsuits from injury caused by the kiln.

[Mark C.]

46 minutes ago, DewDropDawn said:

16 feet between subpanel and kiln outlet.  Well, all the drywall and insulation just finished and the 3 electricians here think differently and now this could be a problem.  Thanks for all the info and heads up.  

Have been in the business for over 40 years its not like the electricians are recreating the wheel. As I said most electricians just look at the amp draw label and wire for that . But with a kin its not going to work out. How do I know that well now that you asked I tried it. It was long ago and what happens as I noted early is the breaker will fail  very early and the wires can overheat especially on the ends. You can also ruin your subpanel. Seen it all before.

You have 3 electricans so thats at least 6 opinions right there .

The 25% rule is there for a reason-kilns are not like electric motors  which draw the most amps at start up then draw far less to operate.

your 30 amp kilns needs a #8 wire and a 40amp breaker-otherwise its unsafe-you now have to decide how to fix this error.

You can cut and repair the sheetrock rip out old wire for new larger wire) or surface mount some conduit on the wall and run it to an wall mounted outlet-which is easier.

Your three electricians where wrong I'm afraid but they learnned something new hopefully or they do bo belive us ether way-You have to live with this and you do not want a fire burning the place down where as those three get to walk away.

My 48 amp kiln uses #6 wire and a 60 amp breaker and I have seen that go sideways as well-all connections need to be perfect. Kilns draw the maxium amps for long periods stressing out all components

[Bill Kielb]

1 hour ago, DewDropDawn said:

16 feet between subpanel and kiln outlet.  Well, all the drywall and insulation just finished and the 3 electricians here think differently and now this could be a problem.  Thanks for all the info and heads up.  

The 125% rule is based on ensuring the breaker does not overheat for this specific load (Kiln or even electric heating circuit). Obviously it requires a 40 amp circuit breaker, the manufacture got it approved that way. So in essence the kiln requires a 40 amp breaker and #8 75c wire.

This code  protects the circuit breaker from overheating. Circuit breakers are rated by UL at 104 degrees in free air cooling. Since they end up in enclosures, NEC and others specify no more than 80% loading is allowed to account for this difference in heating when the breaker is installed in a cabinet. Your electrician should be fully aware of the 80% rule for loading. Turns out the inverse of 80% or 1/0.8 = 1.25. Same rule actually just one is expressed in terms of actual load.

Under the 80% rule a 30 amp breaker could only be loaded to 24 amps in operation.

I think it seems obvious that someone needs to resize the kiln breaker, wiring to it, and wiring to The 60 amp. sub panel. #6 is rated 55 amps, #4 is rated 70 amps. Looks to me like #4/3 NM-B roamex is most likely required for the 60 amp run.

[DewDropDawn]

Again, thanks.  I will consult with the previous owner and find out what type of outlet/wiring used by them.  With all this info, it sounds like the licensed and bonded electricians providing estimates for wiring/breaker install, and the EE hired to do the work, with the knowledge and information about the kiln are seemingly NOT as educated/knowledgeable as y'all.  We're done here in this conversation because now I am angry and will NOT use the kiln which is ***** up given I paid a licensed/bonded EE to do the job based on their experience, ratings and knowledge.   Thanks for helping me  learn how to wire the outlet itself only - not really.  

 

 

[Mark C.]

Sorry about this maybe you could ask them to redo the work on thier dime as its subpar .You could offer to pay for the upgrade in wire size and they provide thelabor free. As I stated at 1st many electricans do not know about kilns. A studio with any kiln really should have #6 wire at laest feeding the 1st subpanel as Bill Noted. Your #10 is great for most electric water heaters and larger motors just not a 30 amp kiln. We do not know more than them its more that we specialize in just this area of knowledge on kilns.

good luck with the project and be safe