Supplying 208V rated equipment from 240V power supply

FaradayFF

Senior Member
Location
California
Is this kosher if the 208V load can tolerate higher voltage? In this example, it would be a resistive load. Would I have to check the cut sheets for the product to determine if it can be fed from a 240V, 3 phase source?

Thanks!
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Shorter life of the heating elements, possible overheating, tripping of over temp control if so equipped. Buck/boost transformers could be used to lower voltage.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
As a heater rated for operation on 240v will run at almost exactly 75% power, I imagine a heater rated for 208v would run at the reciprocal, or 133% rated power.
 

kwired

Electron manager
Location
NE Nebraska
Is this kosher if the 208V load can tolerate higher voltage? In this example, it would be a resistive load. Would I have to check the cut sheets for the product to determine if it can be fed from a 240V, 3 phase source?

Thanks!
Each load you might encounter may have a different answer to this question.

When it comes to heaters, many are designed for 240 volts, but also have a marked 208 volt rating.

I know of one particular line of cove heaters I use that sells 208 volt ,240 volt and 277 volt units - same watts per foot, different input volts. They are designed to operate at a certain optimal temp and overtemp may destroy them.Their warranty is no good if there is any evidence a unit is connected to a higher voltage than rated for and they state that in the instructions. I have had a couple warranty cases and first thing they ask is what voltage it is connected to.
 

charlie b

Moderator
Staff member
Location
Seattle, WA
Occupation
Electrical Engineer
Whether it would be safe and whether it would even work at all are separate issues. But unless the manufacturer's documentation declares that the equipment is rated for both voltages, it would be a violation of 110.4 to install it the way you describe.
 
Top