Steamer wire size and disconnect

[mike33]

I am installing a new steam generator in a new location. The spec sheet states:

Input Voltage.....208-240VAC Single Phase
Kilowatt Rating....15.0
Maximum Amperage.......69 AMPS

I am using 240V. The paperwork also says use #4 wire and a 90amp breaker. So will this setup work?

A 90Amp breaker at main panel.
Approx 100feet of 1" EMT / flex.
(2) #4, (1) #8 ground.
A 100Amp? Non fused disconnect in the attic next to the steamer.

 

[Dennis Alwon]

At 240V I am assuming the unit is rated 69 amps. If 125% is needed then a #3 at 75C would be needed.

 

[mike33]

How do I know which column to use? Wire rating and termination rating? The unit has a label on it saying to use #4. And it provides #4 in a power whip to attach to a disco. Maybe because #4 is rated to 85amps and they consider it close enough?

Is there any "special section" in the NEC for steam units, like air conditioner motors?

 

[beanland]

Need better data

Need better data

Here is a problem: if the generator is rated 15,000W @ 208V then the current has to be 72A. If the 69A is at 240V, then the power is 16.6kW. Now, this assumes that this is a resistive device so current is proportional to voltage. 15,000W @ 69A would be 217V. So, what is this device really rated at the voltage being used?

 

[augie47]

As noted by others, they have given you some numbers that promote questions.
15 kw at 240 would be 62.5 amps. Are there any loads other than the heater (motor, controls, etc) ?

I would feel comfortable going by their paper work. If they advise a #4 wire and a 90 amp breaker they must have 75? termination points. I see no need for a 125% rating unless you know the load is continuous.

 

[mike33]

I just called Thermasol. They said someone else called recently about this discrepancy on another unit so their engineer looked into it and gave them a response to give installers.

The 15kw at 240 is correct. The 69AMPs is a cushion for some kind of "safety rating" for NEC.