Tankless hot water install ( Wire size ? )

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Davebones

Senior Member
Location
North Of Tampa Fl
One of our product lines had a Eemax EX180T2T tankless hot water heater installed in their area . It is rated 18kw , 3 phase , 480v , 22 amps . Opening the cover we see inside a note calling for #6 or larger wires to feed it . Why would they call for a #6 wire while the load is only 22 amps ? Had planned to feed it with a 40 amp circuit with #8 .
 
Not sure why #6 is being called out but I think 40 amps is too high for the ocpd.... 22 amps x 150% = 32 amps... next size 35 amps

410.11(E) Single Non–Motor-Operated Appliance. If the branch
circuit supplies a single non–motor-operated appliance, the
rating of overcurrent protection shall comply with the following:
(1) Not exceed that marked on the appliance.
(2) Not exceed 20 amperes if the overcurrent protection
rating is not marked and the appliance is rated
13.3 amperes or less; or
(3) Not exceed 150 percent of the appliance rated current if
the overcurrent protection rating is not marked and the
appliance is rated over 13.3 amperes. Where 150 percent
of the appliance rating does not correspond to a standard
overcurrent device ampere rating, the next higher standard
rating shall be permitted
Click to expand...
 
infinity said:
According to the manufacturers spec sheet that unit is 208 volts.

Click to expand...
The same model and add - 277 and you get the 480v version

www.prodryers.com

Eemax EX180T2T-277-DI De-Ionized Electric Tankless Water Heater, 18kW, 480/277V, Three Phase, 22 Amps, 0.7 GPM Turn On

Buy the Eemax EX180T2T-277-DI 18kW 480Y/277V De-Ionized Three Phase Tankless Water Heater on sale. Get the best price and free shipping now!
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infinity said:
According to the manufacturers spec sheet that unit is 208 volts.

Click to expand...
That would make 6 AWG the correct selection wouldn't it ;)

Bet some those on assembly line either forgot or simply don't know not to put that label on the -277 model.

Kind of makes you wonder if actual watts is correct as well. They very well might just use same elements but connect them in wye for high volts and delta for low volts.
 
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