Engineer Wants (3) 208V 20A Hand Dryers on 30A Circuit

[Willoferd]

We have been propositioned by an engineer to provide a single 30A 1ø 208V circuit to service (3) 20A 1ø 208V hand dryers. There is suitable available amperage to run all the hand dryers at the same time, but my question is; is there anything in the code that prevents us from installing a piece of hard wired equipment like that on a circuit that is well over the max amps of the device? Let me know if clarification is needed.

 

[charlie b]

The only thing I can offer is to look at the instructions included with the dryers. If they call for a 20 amp circuit, then you cannot use a 30 amp circuit. Other than that possibility, I could not find a specific NEC article that would prohibit this installation.

 

[kwired]

I agree with what charlie said.

Most the time they don't run long enough and you might never trip the 30 amp device. However I will say if there is a situation of heavy usage I would think there is some risk of tripping the 30 amp device, like in a restroom and several people get a break from some activity all at same time - that usage in such situation might be enough.

 

[powerpete69]

The only hopefully obvious thing not stated is that you would have to use at least #10 wire throughout the loads.

 

[kwired]

I'd rather see them balanced across all three phases - still going to be about 35 amps with all three running though, but like the chances of that holding even on a 20 amp three pole better than having 60 amps on a 30 amp two pole breaker.

 

[Willoferd]

My concern wasn't with overloading the circuit, but I think Charlie B answered my question. I was more concerned with a fault causing the device to continuously run or possibly draw more than the 20A it was designed to withstand. Seems like there should be something in the code to prevent this.

 

[infinity]

What is the make and model # of the hairdryer? I would think that the manufacturer requires an individual branch circuit for the hand dryer.

 

[Willoferd]

It's an XLERATOR Hand Dryer. The engineer reneged on his request for a single circuit for 3 hand dryers. We are now providing dedicated 20A circuits to each HD. Thank you all for the input!

 

[infinity]

That unit only draws 5.6 amps on 208 volts so three on a 20 amp circuit wouldn't be a problem.

ELECTRICAL:

Volts: 208-277V

Amps: 5.6-6.2A

 

[charlie b]

The engineer reneged on his request . . . .

I generally prefer to disregard any "unusual" ways our members express their views and describe their issues. But I feel the need to come to the defense of a fellow engineer. The word "reneged" carries the general connotation of "failed to honor a promise." I gather that your intended meaning was to say that the engineer "withdrew his request."

 

[jap]

There are other definitions of "reneged", such as, "to withdraw from" or to "retract".

In defense of our fellow OP, I don't think he was being too hard on the engineer.

JAP>

 

[kwired]

That unit only draws 5.6 amps on 208 volts so three on a 20 amp circuit wouldn't be a problem.

20 amps does seem like it would be a little excessive on the heat doesn't it, but OP only says 20 amp and not real clear if that is actual unit rating or max circuit rating.

 

[LarryFine]

20 amps does seem like it would be a little excessive on the heat doesn't it, but OP only says 20 amp and not real clear if that is actual unit rating or max circuit rating.

I'd say it's a minimum circuit rating, but still okay for more than one dryer per circuit.

 

[infinity]

20 amps does seem like it would be a little excessive on the heat doesn't it, but OP only says 20 amp and not real clear if that is actual unit rating or max circuit rating.

The actual rating was in post #9 which you quoted.

 

[Dennis Alwon]

I not sure you can install the units on a 20 amp circuit. It is interesting because the code does not seem to deal with appliances that have both motor and heating elements. The hand dryer is an appliance and art. 422 mentions non motor appliances and motor appliances but not both except for specific appliance like a dishwasher.

So what guidance do we have in calculating the load of 3 separate hand dryers at 5.6 amps apiece. Do we take 125% of the largest load and add the other loads and then be limited to art. 430 at 250% or can we use the non motor appliance and use max 150% as stated in art. 422?

Or does 210.23(A)(2) come into play-- does not quite fit either IMO.

(2) Utilization Equipment Fastened in Place. The total rating
of utilization equipment fastened in place, other than luminaires,
shall not exceed 50 percent of the branch-circuit ampere
rating where lighting units, cord-and-plug-connected utilization
equipment not fastened in place, or both, are also supplied.

 

[infinity]

I not sure you can install the units on a 20 amp circuit. It is interesting because the code does not seem to deal with appliances that have both motor and heating elements. The hand dryer is an appliance and art. 422 mentions non motor appliances and motor appliances but not both except for specific appliance like a dishwasher.

So what guidance do we have in calculating the load of 3 separate hand dryers at 5.6 amps apiece. Do we take 125% of the largest load and add the other loads and then be limited to art. 430 at 250% or can we use the non motor appliance and use max 150% as stated in art. 422?

Or does 210.23(A)(2) come into play-- does not quite fit either IMO.

I'm not sure that any of that applies so you're left with a maximum of roughly 17 amps of non-continuous load which is fine on a 20 amp circuit.

 

[kwired]

I'm not sure that any of that applies so you're left with a maximum of roughly 17 amps of non-continuous load which is fine on a 20 amp circuit.

I agree, they are designed so they can not run continuously even if you want them to AFAIK. Auto user sensing ones maybe could, your hands might be baked after three hours though.

 

[480sparky]

That unit only draws 5.6 amps on 208 volts so three on a 20 amp circuit wouldn't be a problem.

Wouldn't it be 6.2A @ 208?

 

[kwired]

The actual rating was in post #9 which you quoted.

Where did it come from though? OP never gave any model number that I was aware of.

 

[infinity]

Wouldn't it be 6.2A @ 208?

6.2 amps is for 277 volts. At 208 volts it's rated at 5.6 amps. Resistive load, lower voltage means lower current since current and voltage are directly proportional.

I took the information off of the Xlerator product page.