Single phase dryers on 3 phase service

Dconger74

Member
Hello, new here. I am studying so that I can pass my Master exam. I want to be prepared so I am asking if anyone could give and example of what I posted in the title. Mike’s textbooks show examples for cooking equipment but not dryers. I believe it is the same procedure as cooking equipment except you use table 220.54. Just want to be sure. Thanks.
 

infinity

Moderator
Staff member
Are you asking about an Article 220 service calculation with 1Ø dryers on a 3Ø system?

Welcome to the forum. :)
 

LarryFine

Master Electrician Electric Contractor Richmond VA
DC, welcome to the forum.

Rather than code items, let me explain this: a clothes dryer has everything connected from L1 to the neutral, except for the heating element.

A 240v heating element runs at almost exactly 3/4 the wattage on 208v as on 240v. The rest of the dryer's internals run on 120v either way.
 

kwired

Electron manager
DC, welcome to the forum.

Rather than code items, let me explain this: a clothes dryer has everything connected from L1 to the neutral, except for the heating element.

A 240v heating element runs at almost exactly 3/4 the wattage on 208v as on 240v. The rest of the dryer's internals run on 120v either way.

That is the simple part, calculating load with allowed demand factors on a three phase supply is the part that is complicated, and even on this site you get varying opinions on how it should be done.
 
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