Dryer Outlet
- Thread starter jimmie
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Re: Dryer Outlet
I think the only definition for continuous load is in article 100.
Continuous Load. A load where the maximum current is expected to continue for three hours or more.
Do you expect the maximum current to continue for three hours or more?
Hard wiring wont make any difference if it's on an individual circuit.
Look at 210.23 and 210.23(A) thru (D).
Edit: There's 210.19(A)(1) and 210.20(A) also.
[ April 13, 2005, 07:59 PM: Message edited by: physis2 ]
I think the only definition for continuous load is in article 100.
Continuous Load. A load where the maximum current is expected to continue for three hours or more.
Do you expect the maximum current to continue for three hours or more?
Hard wiring wont make any difference if it's on an individual circuit.
Look at 210.23 and 210.23(A) thru (D).
Edit: There's 210.19(A)(1) and 210.20(A) also.
[ April 13, 2005, 07:59 PM: Message edited by: physis2 ]
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- Windsor, CO NEC: 2017
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Re: Dryer Outlet
(Remember, the dryer will shut off when the load is dry, which would generally be less than three hours. Per code, any break in three hour's time resets the clock.)
(Remember, the dryer will shut off when the load is dry, which would generally be less than three hours. Per code, any break in three hour's time resets the clock.)
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Re: Dryer Outlet
And the heating element is thermostat driven.
And the heating element is thermostat driven.
Re: Dryer Outlet
However, branch circuit capacity is required to be a minimum of 125% of the current drawn by an electrtic heater even if the heater is not a continuous load. The only exception is for certain industrial circuit breakers and fusible switches that are rated to continuously carry 100% of rated current.
The motor is also a continuous load or at least continuous in the eyes of article 430. As far as article 430 is concerned you need 120% of the heater current plus 125% of the motor current.
Skimping on branch circuit capacity is just poor economy and not just asking for a fire. If it runs cooler it lives longer and more electricity reaches the load. When you heat up wires you are paying for electricity and not getting it.
There was at one time a household dryer that needed a 50 amp circuit but fell out of favor for 2 reasons. First, only a family with 8 or more children has a use for it. The other is that after accounting for special wiring and other expenses you can just as easily have a second electric dryer or a 2nd dryer that runs on natural gas or propane.
A second dryer can also be done with indoor clotheslines and a dehumidifier and you probably will get more utility out of the dehumidifier. The dehumidifier is needed when an outdoor clothesline will work.
However, branch circuit capacity is required to be a minimum of 125% of the current drawn by an electrtic heater even if the heater is not a continuous load. The only exception is for certain industrial circuit breakers and fusible switches that are rated to continuously carry 100% of rated current.
The motor is also a continuous load or at least continuous in the eyes of article 430. As far as article 430 is concerned you need 120% of the heater current plus 125% of the motor current.
Skimping on branch circuit capacity is just poor economy and not just asking for a fire. If it runs cooler it lives longer and more electricity reaches the load. When you heat up wires you are paying for electricity and not getting it.
There was at one time a household dryer that needed a 50 amp circuit but fell out of favor for 2 reasons. First, only a family with 8 or more children has a use for it. The other is that after accounting for special wiring and other expenses you can just as easily have a second electric dryer or a 2nd dryer that runs on natural gas or propane.
A second dryer can also be done with indoor clotheslines and a dehumidifier and you probably will get more utility out of the dehumidifier. The dehumidifier is needed when an outdoor clothesline will work.
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- Windsor, CO NEC: 2017
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- Service Manager
Re: Dryer Outlet
Michael, I agree with you in sentiment, bigger is better. As I am currently thinking, Article 220 sets the minimum dryer wattage at 5000W, which is under 21 amps at 240 volts.
Can you cite code references, please?
Michael, I agree with you in sentiment, bigger is better. As I am currently thinking, Article 220 sets the minimum dryer wattage at 5000W, which is under 21 amps at 240 volts.
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- Lockport, IL
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Re: Dryer Outlet
When 220.18 says to use 5000 watts (or the nameplate rating, whichever is higher) for the load calculation, you do not have to add a 25% factor on top of that. No matter that there is a heater or a motor. The code points to other sections for space heaters (which this is not!) and for motors. But it has an explicit description of what to do with dryers.
I would call this dryer a 25 amp load. That is 83.3% of the rating of a 30 amp branch circuit. True, but irrelevant. Per the second sentence of 210.23, since this is an individual branch circuit (i.e., no other outlets), the load can be as high as 30 amps.
Bottom line (in the order of your questions):
(1) No.
(2) Yes.
(3) Yes.
When 220.18 says to use 5000 watts (or the nameplate rating, whichever is higher) for the load calculation, you do not have to add a 25% factor on top of that. No matter that there is a heater or a motor. The code points to other sections for space heaters (which this is not!) and for motors. But it has an explicit description of what to do with dryers.
I would call this dryer a 25 amp load. That is 83.3% of the rating of a 30 amp branch circuit. True, but irrelevant. Per the second sentence of 210.23, since this is an individual branch circuit (i.e., no other outlets), the load can be as high as 30 amps.
Bottom line (in the order of your questions):
(1) No.
(2) Yes.
(3) Yes.
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: Dryer Outlet
A cord connected load that is powered by an individual branch circuit can be 100% of the circuit's rating. Look at 210.23, third sentence. You don't get refered to 210.23(B), the place where the 80% limit comes into play, unless there are two or more outlets.
A cord connected load that is powered by an individual branch circuit can be 100% of the circuit's rating. Look at 210.23, third sentence. You don't get refered to 210.23(B), the place where the 80% limit comes into play, unless there are two or more outlets.
Re: Dryer Outlet
Thank you. Charlie B.
FYI - While field experience tells use that 95% of the time we're going to install a 30 amp circuit with a 30 amp 4w receptacle. A couple of text books I was using had different rational
like; Not to exceed 80% or taking the load and multiplying the load by 125% and another simply saying over 20 amps "round up". It appears that many of these text books "based on the NEC" are subject to the authors interpetation.
Thank you. Charlie B.
FYI - While field experience tells use that 95% of the time we're going to install a 30 amp circuit with a 30 amp 4w receptacle. A couple of text books I was using had different rational
like; Not to exceed 80% or taking the load and multiplying the load by 125% and another simply saying over 20 amps "round up". It appears that many of these text books "based on the NEC" are subject to the authors interpetation.
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