Electrical questions regarding kiln set up in home studio

[LJay]

I am hoping to buy a skutt kmt 818 30a. 

Here is what I know...

My breaker box has a 240 volt 30 amp for the dryer.  The kiln is 21.7 amps and 240 volt

Here's what I'm hoping...

I want to change the plug so it can be used in the dryer plug. And hopefully 72 percent of power usage is close and safe enough to the 80 percent rule. 

Ultimately I want to know if the parameters I have will allow me to install this kiln? Happy to fill in any blanks I left out, just let me know. Thanks!

[davidh4976]

Edited: I missed the  KM-818-30A-3 which indeed draws 21.7 amps.

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A Skutt KMT818 240V kiln draws 26.7 amps (not 21.7) and requires a 40 amp breaker/circuit.

The U.S. National Electrical Code requires the circuit breaker for a kiln be between 125% and 150% of the kiln's rating. For 26.7 amps, the 125% rating gives 33.4 amps and therefore a 40 amp breaker/circuit is required for the KMT818.

Edited November 29 by davidh4976

[PeterH]

15 minutes ago, davidh4976 said:

A Skutt KMT818 240V kiln draws 26.7 amps (not 21.7) and requires a 40 amp breaker/circuit.

+1
https://skutt.com/product_pdf_generator_prod_page.php?ItemNo=5466&to_screen=no&type=ceramic&model=KMT-818

[iffetorbay]

@LJay, apart from the above warnings concerning the requirement of a 40 amp breaker,  it is also important not to change the original plug of the kiln you will buy, Otherwise you may lose your warranty. Rather than modifying the plug that the kiln will come with,  you should have your existing dry outlet changed !!! SKUTT specifies the configuration of the required receptacle (outlet) on the technical table  as «NEMA 6-50» , which @PeterH has shared above with a link! But this is a job for a certified electrician, and the safe amp capacity of the feeding cable, from the circuit breaker to the new receptacle, should respect the norm !

 

[Hulk]

Note: the KM-818-30A-3, 240V 1P is a Cone 8 kiln, draws 21.7 Amps

...handy for using your existing thirty amp circuit,
however, it's a cone 8 kiln, which will very likely require new elements sooner than a cone 10 kiln would, especially if firing to cone 5/6

Changing out the socket/outlet vs modifying the cord, agreed.
Another option would be to eliminate the plug->socket by wiring "direct"...

Give me a shout sometime, Chico!

Edited November 27 by Hulk
outlet

[Mark C.]

My guess is that wire for the 30 amp plug is #10 wire and you will need larger wire to get to 40 amp like a #8 wire. If you are going thru all that trouble consider #6 wire for a larger kiln later on like #6 wire for 50 amps in the future 

[PeterH]

On third thoughts ...

There are (at least) 3 240V models of the skutt kmt 818
https://skutt.com/skutt-resources/resources-just-for-you/architectural-specifications/electrical-specifications/?srsltid=AfmBOorO0T_x2RPB_FlEhVYqHftj-ypRTSN5HtubMNn2h3nJXUClKx6I

                                              phase                                                                                         NEMA
KM-818          1       240V    26.7A   6400W   6-50
KM-818-3        1       240V    26.7A   6400W   6-50
KM-818-30A-3    1       240V    21.7A   5200W   6-30

David's reply applies to the first two models. But as @LJay said "I am hoping to buy a skutt kmt 818 30a" they were referring to the  KM-818-30A-3. At 21.7A this presumably needs a breaker between (21.7*1.25 & 21.7*1.5) i.e. (~27A & ~32A).

Some residual observations/concerns:
1) Is the dryer wiring rated at 30A continuous load? I'm in the UK and have no idea.
2) The KM-818-30A-3 is rated at cone 8 rather than the cone 10 of the other two models.

2a) What cone are you intending to fire to, and are you happy with the likely element life?
 

Edited November 27 by PeterH

[Mark C.]

#8 wire is your minimum size for that kiln -Your dryer 30 amp is most likely #10 wire not big enough 

Edited November 28 by Mark C.

[LJay]

Thank you everyone for your replies. 

I was also able to reach out to Skutt tech support as well. I have learned a lot! My next step is to see what wire is behind the dryer, fingers crossed for 8 gauge otherwise this project is a no go. 

I am planning to fire to cone 5/6. And confirmed that 818 30a is the only kiln I have found suited for my parameters (provided I have 8 gauge wire) but sounds like that may not be the case. Unfortunately direct wire is not an option for me in this set-up. So I will have someone qualified to check that out for me. 

Again thanks for all the information, it has been informative! I'll keep y'all posted on the progress.

[Bill Kielb]

1 hour ago, LJay said:

I am planning to fire to cone 5/6. And confirmed that 818 30a is the only kiln I have found suited for my parameters (provided I have 8 gauge wire) but sounds like that may not be the case. Unfortunately direct wire is not an option for me in this set-up. So I will have someone qualified to check that out for me. 

Just a note ALL the above has been spot on. I always encourage heavier wire when available to limit the voltage drop to as low as practical. The 818 - 30A requires #10 gauge copper wire per Skutt and NEC code so that might be an interim install. Direct wire or just adding the correct receptacle to presumably your existing flush mount receptacle using an extension ring is a typical way an electrician can non destructively do this. Both loads would never be able to operate concurrently though, very much like when we restrict loads to operate when an EV charger is installed in homes with only 100a service.

The #10 wire, cone 8, - likely a lack of ventilation among other issues not ideal but may provide an opportunity to an interim solution. Technically 10 gauge is allowed for the 818 30a. I would always suggest the next size up for voltage drop reasons, but #10 is allowed for this model.

Edited November 28 by Bill Kielb

[neilestrick]

@LJay  The simplest solution to all this is to simply buy a different brand of kiln that meets your 30 amp requirement and fires to cone 10 so you get good element life:

The L&L e18S-3 pull 23.9 amps and is rated for cone 10. It needs a 30 amp breaker, and you can request a number of different plug configurations and cord lengths to make it work with your dryer outlet.

The Olympic MAS1818HE also pulls 24 amps, is rated to cone 10, and uses a 30 amp breaker.