Pushing 240V through a 208V heating element

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topgone

Senior Member
So how can we use NEMA standard motors? The nameplates are required to be marked 230 volts for use on a nominal 240 volt system, and 460 for use on a nominal 480 volt system. :)
The key word is "nominal"! A word used to describe something that is lower than the actual value of the said thing! From Wiki:
nom·i·nal (/ˈnämən(ə)l/), adjective - (of a price or amount of money) very small; far below the real value or cost.
 

ledolectric

Member
I had a commercial steam table haha from chyna, and it was 208 volt but the premises had 240 so I called the manufacturer(office in Queens, NY) and asked if it was ok to wire it to the 240 line and was literally YELLED at by some crazy Asian woman.. “208 onry” “208 onry”... so I put a buck boost transformer in and solved the issue.. I did another one where I used an auto transformer that “adapts” to the load.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
I would wager the elements of any restive heating appliance made in China is for 220VAC.
For any of you interested North and South American nominal 60 hz voltages are defined in ANSI C84, a nominal voltage is defined for transmission, distribution and utilization equipment. And recently 220 is the same as our 208 in our ANSI C84 spec for nominal voltages. I have been quite fascinated to see many 220Y127 systems replacing 208Y120.
ansi-C84-20.png However thats the upper limit so 240V is out of spec.
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Registered Professional Engineer
But if you would double the [transmission or distribution] voltage you would have to change supplied transformers or change taps if designed with that option, you don't just double voltage and do nothing else in this situation.
The recurring theme here is that you cannot just hook up a device to a higher voltage without changing something.
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Registered Professional Engineer
I don't know if that's right but I like the analogy, how about the little dumps trucks stay the same number but can handle a larger load because of their beefier engines. Sorry couldn't resist.
They can't handle the larger load for long without something overheating and failing. That's the whole point of this thread.
 
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