Older kiln wiring

[Fawn]

Hello, I have just received an older kiln (paragon A82B). It looks to be in really great shape as there are no cracks/holes in any of the bricks, just a couple of knicks here and there. The elements look to be in good condition and seated well with the exception of a couple of spots raised just a bit. Overall I am very pleased with it.

I have never had a kiln before so this is all really new to me. My main question is, what  breaker size do I need and what size/kind of  wiring should I have installed to the breaker?

[Bill Kielb]

Your instruction manual is here https://paragonweb.com/wp-content/uploads/IM5-A-and-B-Paragon-Inst-Man-Jan2017.pdf

page 6 outlines the electrical specifications which you should confirm matches the data plate on the kiln. Your electrician will need to refer to these requirements which appears to be 40 amp two pole breaker and number 8 wire (minimum). This kiln requires a 4 wire circuit so: two phases (240v) one neutral and a ground makes four wires.  Your electrician should size as specified throughout and wire per code.

[neilestrick]

Double check the serial plate-  that kiln pulls 30 amps, but code requires that kilns be on a breaker that is rated 25% greater than the draw of the kiln, so it needs a 40 amp breaker. Your electrician probably won't know that and will want to put it on a 30 amp breaker, so make sure he is aware of the code. The neutral should be a separate wire from the ground. The kiln should have a 4 prong plug.

[Fawn]

Yes the kiln has a 4 prong plug. My husband is not an electrician,  but has wired whole houses before with zero problems. Just had to do research about wire sizes for some things. We are use to running stuff like 12/2, 6/3, 8/3, 10/2 etc. We just can't really find the exact wire size to run for this kiln, which is why I came here. I called paragon, but they are not open on Fridays and we wanted to get this done tomorrow. My husband is at work right now, so I was trying to find out the wire size for him. The previous replier said #8 wire and kiln requires a 4 wire circuit, does that mean I need 8/4 wire?

[Bill Kielb]

2 hours ago, Fawn said:

he previous replier said #8 wire and kiln requires a 4 wire circuit, does that mean I need 8/4 wire?

Yep, (I’m that previous replier) if you direct your husband to the Link and page I cited he will know. Technically if you are using non metallic cable it will be 8/3 with a ground. And heavier if it’s a long run. Please be sure it’s copper and follow your local codes as well as use a four wire 50 amp plug and receptacle if not direct wired.

here is the spec from the link above (p6), once he sees this I think he will know. If not, for a continuous resistive load as Neil mentioned everything is sized at 125% which is why the manufacture says number 8 and 40 amps. Follow the manufactures directions and local code and my comment about this being two 120v circuits a neutral and ground and you should be fine.

Here is a link for the wiring diagram as well. The neutral IS essential. https://paragonweb.com/wp-content/uploads/A82B_A823B_A81B_A88B_AA8B_AA8B3B_WD_PL.pdf

PS for voltage drop the rule of 3% is excessive for kilns. 1% or less is way better.

Edited July 8, 2022 by Bill Kielb

[Fawn]

2 hours ago, Bill Kielb said:

use a four wire 50 amp plug and receptacle if not direct wired.

I'm a little confused on what that means. So, If it's not direct wired (which it's not going to be) I need a 50 amp plug that is plugged into a 50 amp receptical which is wired to the breaker box with 8/3 wire onto a 40 amp circuit breaker?

The cord that came on the kiln is a 6 AWG wire. Is that wire fine or do I need to replace it?

[Fawn]

Also, would it be better to run 6/3 wire instead of 8/3 on a 40 amp breaker just incase I upgrade to a larger kiln in the future? 

[Bill Kielb]

2 hours ago, Fawn said:

The cord that came on the kiln is a 6 AWG wire. Is that wire fine or do I need to replace it?

I don’t believe they make 40 amp receptacles or they are uncommon,  50 amp is common. It’s ok for connecting items and wiring to be rated more than they will carry. Not less though else the 40 amp breaker will not protect them and they become the fuse. #6 awg cord is common and fine to be overrated. The cord has conductors next to each other in a confined space so it will heat up more and, it has to remain flexible over its life so good practice for the cord to be sturdy and over rated as well as the plug and receptacle.

 

2 hours ago, Fawn said:

Also, would it be better to run 6/3 wire instead of 8/3 on a 40 amp breaker just incase I upgrade to a larger kiln in the future

I like your thinking and would normally suggest if it’s financially feasible for the exact reason you state. Besides it will reduce the voltage drop which puts more power in the kiln and less heating in the wire even if only a minor amount.

You need to get the breaker size right though to protect everything appropriately. Neil mentions the not less than 125% nor more than 150% of the actual kiln load for sizing in North America because electricians often are not familiar.

Since you are running cable, last mention - whether 6/3 or 8/3 mąkę sure it includes an earth ground, JIC it is needed, it is there. For this kiln you need ALL 4 wires.

Edited July 9, 2022 by Bill Kielb

[neilestrick]

If you run 6ga wire now you'll be able to use a 48 amp kiln on it later, which is good for most home studio sized kilns.

[Fawn]

Thank you both for this helpful information!