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Confusion About 120 Volt Outlets

Left: 120 volts, 20 amps, NEMA 5-20R; Right: 120 volts, 15 amps, NEMA 5-15R.


Confusion About 120 Volt Outlets

Reader Response: A kiln on a deserted island

Recent Q&As: A warm kiln cord and plug; firing glass in an enameling kiln; firing glass and silver in the same kiln

Memorable Quote



About once a week, someone tells us, “The 120 volt plug on my new kiln doesn’t match my wall outlet.” Many people do not know the difference between 15 amp and 20 amp, 120 volt wall outlets, because they look almost the same. But a 20 amp, 120 volt kiln cannot be plugged into a 15 amp, 120 volt wall outlet.

The common 15 amp, 120 volt household outlet (also called a receptacle) is used throughout North America. Lamps, vacuum cleaners, refrigerators, etc. plug into it. The outlet has two vertical slots; the U-shaped hole is for the green safety grounding wire.

The 20 amp, 120 volt outlet looks like the 15 amp outlet, except one of the vertical slots is shaped like a sideways T. The photo shows the 20 amp outlet on the left and the 15 amp outlet on the right.

NEMA, the National Electrical Manufacturers Association, has standardized these designs and designated them NEMA 5-15R and 5-20R. (The number after the hyphen indicates amperage.)

Standardized plugs and outlets are so ubiquitous that we rarely think about them. But they helped to bring electricity into millions of homes and factories.



“I sometimes wish to be on an island all by myself, with just my torch, the glass, and the kiln,” wrote Paragon kiln owner Rosemarie MacDonald in Australia. I often hear from people who love kilns.



Q. I’ve read in my kiln manual that the plug is not supposed to get hot. It can get warm, but I've touched it and it’s more then warm. Is the outlet is worn out?

A. You are a good kiln operator. If you are aware of the cord temperature, you likely also take care of your kiln. A hot plug indicates that the connections between the wall outlet and the cord prongs are loose. I would replace the cord set and the wall outlet. You should definitely not fire a kiln that has a hot plug.

Q. Can glass be fired in an enameling kiln that has sidewall elements?

A. Yes. Unless the kiln has door elements, the side toward the door will be slightly cooler than the other three sides, but you can compensate for that by placing items that require a lower temperature near the door.

Q. Can glass and silver be fired in the same kiln?

A. Yes. However, silver and glass should not be fired on the same shelf. The silver molecules in the shelf can migrate over to glass in subsequent firings and discolor the glass. As long as you use different shelves for glass and silver, you can fire both materials in the kiln.



“Read Deep! Read Often! Out-Read the competition! Take Notes! Summarize! Share With Others What You Read!” -- Tom Peters


Pam East, author of “Enameling on Metal Clay,” has produced an entertaining, creative Halloween video that you can watch on YouTube:

Last Wednesday as Todd Lokash, company president, was leaving for the day, he said, “This is my one year anniversary.” He started at Paragon on October 15, 2013. The girls in the office congratulated him and cheered as he walked out the door. Wonderful things are happening at Paragon. I will write about them as they develop.

The last twelve months have been a whirlwind of activity here. Papers have been strewn across my desk and onto two wooden pull-out desk extensions. I’ve been so busy that it wasn't until yesterday, for the first time in a year, that I cleared off my desk. Any time you feel disorganized, clear off your desk or work area. You will feel incredible.

Thank you,

With best wishes,

Arnold Howard Paragon Industries, L.P. – Better Designed Kilns 2011 South Town East Blvd., Mesquite, Texas 75149-1122 Voice: 972-288-7557 & 800-876-4328 / Fax: 972-222-0646 / / /

PRIVACY NOTICE: Under no circumstance do we share or sell your email address.

Copyright 2014, by Paragon Industries, L.P.

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