20 A Receptacle / 25A breaker

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A/A Fuel GTX

A/A Fuel GTX

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Electrician
I have a cord connected air dryer that has a FLA rating of 18 but has a 15 A plug. It will run for up to 4 hours at a time. My thought is it needs a 25 A circuit ( 18 X 1.25= 22.5 A ) and a single receptacle. Can I legally put a 20 A receptacle on a 25 A breaker?
 
first, I believe the cord end is not rated for this unit.

second, according to 210.23 you can't do what you have proposed.

third, FWIW, if the 20 receptacle is 100% rated then a 25A circuit breaker is good for continuous load of 20Amps.
 
A/A Fuel GTX said:
I have a cord connected air dryer that has a FLA rating of 18 but has a 15 A plug. It will run for up to 4 hours at a time. My thought is it needs a 25 A circuit ( 18 X 1.25= 22.5 A ) and a single receptacle. Can I legally put a 20 A receptacle on a 25 A breaker?
Click to expand...

Sounds like a poorly designed unit. You sure it runs for 4 hours without ever stopping or at least cycling the heating element?
 
A/A Fuel GTX said:
I have a cord connected air dryer that has a FLA rating of 18 but has a 15 A plug. It will run for up to 4 hours at a time. My thought is it needs a 25 A circuit ( 18 X 1.25= 22.5 A ) and a single receptacle. Can I legally put a 20 A receptacle on a 25 A breaker?
Click to expand...
Is the cord and plug OEM? ...and if so, is dryer a UL or other NRTL listed product?
 
edward said:
first, I believe the cord end is not rated for this unit.

second, according to 210.23 you can't do what you have proposed.

third, FWIW, if the 20 receptacle is 100% rated then a 25A circuit breaker is good for continuous load of 20Amps.
Click to expand...

Cord is OEM.
 
Smart $ said:
15A circuit is okay. See 430.42 Motors on General Purpose Branch Circuits, (C) Cord-and-Plug Connected...
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Wow, so the 15A attachment plug determines the ampacity of the circuit and not the FLA rating? 210.21 (B) tells me that a 15A receptacle has a maximum load of 12A. The dryer tells me the FLA is 18A. I'm confused:?
 
A/A Fuel GTX said:
Wow, so the 15A attachment plug determines the ampacity of the circuit and not the FLA rating? 210.21 (B) tells me that a 15A receptacle has a maximum load of 12A. The dryer tells me the FLA is 18A. I'm confused:?
Click to expand...
The equipment may be designed such that overload protection is less than FLA. Have you measured the operating current?
 
Smart $ said:
The equipment may be designed such that overload protection is less than FLA. Have you measured the operating current?
Click to expand...

No, I'll be installing the circuit on Saturday. Safest bet to me seems to run #10's, 20 A breaker and a 20 A single receptacle.
 
It sounds like most of the load is the heater not the motor.

if you are going to install all 20 & 20 you might as well install 12AWG. i don't think you will gain anything by installing 10Awg. unless voltage drop, or planning to upgrade to 30A circuit in the future.
 
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edward said:
It sounds like most of the load is the heater not the motor.

if you are going to install all 20 & 20 you might as well install 12AWG. i don't think you will gain anything by installing 10Awg. unless voltage drop, or planning to upgrade to 30A circuit in the future.
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I'm just thinking that to completely cover my bases, the #10 would be a good bet in case in have to install a 25A breaker should there be issues down the road. The run is about 100' and I really don't want to have to re pull it. Besides, with a potential load of 18A, the #10 would eliminate any VD issues as well.
 
It appears to me you have to calculate to at least 5000 watts, or nameplate which ever is greater for electric clothes dryers. NEC 2008 220.14 (B) deals with all occupancies and it refers you to 220.54 for the dryers calculation on branch circuits even though it starts out saying it is for dwelling units feeders or services.
Not sure if your voltage is 120/208 or 120/240 for this dryer.

5000/208 =24.03 amps #10 on a 25 amp breaker. ;) minimum.
5000/240=20.83 amps #10 on a 25 amp breaker minimum I would just do 30 amp myself. ;)
 
brother said:
It appears to me you have to calculate to at least 5000 watts, or nameplate which ever is greater for electric clothes dryers. NEC 2008 220.14 (B) deals with all occupancies and it refers you to 220.54 for the dryers calculation on branch circuits even though it starts out saying it is for dwelling units feeders or services.
Not sure if your voltage is 120/208 or 120/240 for this dryer.

5000/208 =24.03 amps #10 on a 25 amp breaker. ;) minimum.
5000/240=20.83 amps #10 on a 25 amp breaker minimum I would just do 30 amp myself. ;)
Click to expand...

Bro......This is a 120V, air dryer for an auto body shop.
 
brother said:
It appears to me you have to calculate to at least 5000 watts, or nameplate which ever is greater for electric clothes dryers. NEC 2008 220.14 (B) deals with all occupancies and it refers you to 220.54 for the dryers calculation on branch circuits even though it starts out saying it is for dwelling units feeders or services.
Not sure if your voltage is 120/208 or 120/240 for this dryer.

5000/208 =24.03 amps #10 on a 25 amp breaker. ;) minimum.
5000/240=20.83 amps #10 on a 25 amp breaker minimum I would just do 30 amp myself. ;)
Click to expand...

Your calculations are incorrect if this is a mostly resistive dryer load. The voltage increase from 208-240 would increase the current not decrease it.
 
The thing that blows my mind is we have an appliance that supposedly draws 18 amps - likely continuously and it only has a 15 amp cord cap. I don't know why this thing doesn't come with a 30 amp cord cap or even if it should have a cord for the supply.

If it is not a portable appliance then I think it should be designed to be hardwired. Did manufacturer put the cord on it or did some distributor.

If using a 5-15 receptacle stay away from cheap residential grade they will burn out in no time.

You mentioned this was for auto body shop, if 15 or 20 amp 125 volt receptacle you likely also need GFCI protection.
 
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