GrayB Posted January 14 Report Share Posted January 14 (edited) I just bought my first kiln and I’m hoping for advice on how to proceed with the wiring. I’ve done some research online and consulted an electrician, but the answers they are giving me don’t all match up. kiln specs are: 43.98 amps - 10,555 watts - 240 volt - model J230 My kiln is going in an outbuilding separate from my house and it will require about 55-60 feet of cable between my breaker box and the kiln. My electrician told me to use 6/3 copper cable with a 50amp breaker. But from the information I’ve read online it sounds like that may not be enough because of the distance of the wire. Plus the 50 amp breaker doesn’t fall in line with the 125% range for amperage, and 6/3 wire is only rated up to 55amps. Am I over complicating this? Would the 6/3 wire be ok or do I need to go up to 4 gauge wire? Edited January 14 by GrayB Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 14 Report Share Posted January 14 (edited) No you are not over complicating this, follow the manufactures specification. I took a snapshot what I believe your kiln to be (below), if I have the right info, none of the above appears correct. For voltage drop I suggest upsize your wires to limit voltage drop to 1% or less (specifically for kilns). For 60 foot run, that is 120 feet equivalent wire length (Round trip). Depending on which kiln you have it may require a 60 amp circuit, 70 amp circuit - hard to tell without a snapshot of the equipment tag. 43.98 amps is too contrived so that just appears wrong. I would never expect an electrician to suggest more than 80% loading on a residential breaker so that is suspect as well. Your electrician may find the UL requirement for breakers useful: CIRCUIT BREAKERS, MOLDED-CASE AND CIRCUIT BREAKER ENCLOSURES (DIVQ) MAXIMUM LOAD Unless otherwise marked, circuit breakers should not be loaded to exceed 80 percent of their current rating, where in normal operation the load will continue for 3 hours or more. Residential breakers are rated from the factory as 80% devices. 100% rated breakers are generally special and need to be installed in an enclosure approved for them. Edited January 14 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
GrayB Posted January 14 Author Report Share Posted January 14 Thanks for your response/info. I’m not sure why the photos didn’t work on the original post, but hopefully they show here. So I should be ok with the 4/3 cable with a 60amp breaker? Quote Link to comment Share on other sites More sharing options...
Hulk Posted January 14 Report Share Posted January 14 (edited) Looks like the J230 was spec'd as GrayB indicated*. The voltage, aren't most homes supplied with 240v? Be sure that matches up. fwiw, our home is 240v (the kiln's display indicates ~252v). Our run is very near fifty feet. The (e23T-3) kiln's plate indicates 48 amps. I'd considered going with the number four wire, but went with the #6 The cable we bought is rated higher ...75 amps. The vendor, WireandCableYourWay, had a good price** on #6-3C THHN-PVC TRAY CABLE WITH GROUND We also went with a fuse/disconnect box and replaced the supplied cord and plug with a waterproof conduit and #6 wires. *Not sure about the new models, just got several hits for J230 and 43.98 Amps Ah, GrayB uploaded an image. **The per foot price hasn't changed. With shipping, still less expensive than local vendors and better specs. I went with three conductor cable, for down the line someone might need (or want) 120v ...the third conductor is not being used in our setup. My understanding is the kiln (our kiln, the e23T) requires two conductors only, and the ground. Edited January 14 by Hulk see image uploaded by GrayB, above; conductor count Bill Kielb 1 Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 14 Report Share Posted January 14 (edited) Interesting spec!! 10555 w / 240 => 43.98 amps. Minimum breaker size 43.98 X 1.25 =54.97. Maximum breaker size = 43.98 X 1.5 = 65.97. So 60 amp is your lowest pick and manufactures specifications. Ran a voltage drop for #6 (copper) cable and it is just over 1%. Check your calculation with the cable you pick. Note 60c non metalic cable is likely only rated at 55 amps, you will need higher quality cable to meet or exceed 60 amps as Hulk mentioned. Any additional 120v load (future) will require a neutral and ground so not sure having one extra no. 6 is useful. 1” PVC conduit definitely allows options and for future expansion. Equipment ground requirement for 60 amps is #10 copper I believe - however you do it. @Hulk is correct, for service and isolation reasons I would install a disconnect. Relying on the plug as a means of disconnect not the greatest of choices for an outside location 60 ft away from being able to shut it off. Edited January 14 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
GrayB Posted January 14 Author Report Share Posted January 14 (edited) Thank you both for your help! My voltage supply is 240v. @Hulk thank you for the source on the cable. That is definitely cheaper than the 4/3 and local prices. I’m an amateur in this field, do you know why the 6/3 cable that you recommended is rated at 75amps while the 6/3 I’ve found locally is only rated up to 55? I’m just curious what the difference might be since they’re both the same size. Edited January 14 by GrayB Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 14 Report Share Posted January 14 (edited) 1 hour ago, GrayB said: do you know why the 6/3 cable that you recommended is rated at 75amps while the 6/3 I’ve found locally is only rated up to 55? I’ @GrayB Temperature - your insulation is rated 60c, his is 90c Edited January 14 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
Mark C. Posted January 14 Report Share Posted January 14 I often choose THHN when wiring here are some types of differeances on some charts The coating decates the use and temps https://www.wireandcableyourway.com/blog/choosing-between-thhn-xhhw-wire/?gad_source=1&gclid=CjwKCAiAqY6tBhAtEiwAHeRopQ5ofpUdnQbzmOLVCFhn9H-0HVO55GKrZTS6HYB0_BJq2iKmCCMSLRoCiUkQAvD_BwE Quote Link to comment Share on other sites More sharing options...
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