Backfeeding a Circuit Breaker

FaradayFF

Senior Member
Location
California
Greetings,
Does a typical thermal magnetic circuit breaker retain its tripping characteristics regardless of the direction of the current flow through it? If one connected a temp. generator to a panelboard branch circuit breaker forcing the current in the opposite direction to expected(conventional) load flow direction, would the breaker trip if its amperage rating was exceeded?
I think so, these tripping elements in the molded case units are not direction sensitive, are they?

Thanks,
EE
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
It seems the breaker wouldn't "know" or "care" which way the current is flowing. The only difference I can see is that the contacts are normally on the load side of the elements.
 

jaggedben

Senior Member
Greetings,
Does a typical thermal magnetic circuit breaker retain its tripping characteristics regardless of the direction of the current flow through it? If one connected a temp. generator to a panelboard branch circuit breaker forcing the current in the opposite direction to expected(conventional) load flow direction, would the breaker trip if its amperage rating was exceeded?
I think so, these tripping elements in the molded case units are not direction sensitive, are they?

Thanks,
EE
I'm nearly 100% certain that a 'typical' thermal magnetic circuit breaker operates the same in either direction, if by 'typical' we mean no special electronics features such as GFCI, AFCI, or GFP. I have never seen a 'typical' thermal magnetic breaker marked Line and Load from the factory. FWIW, I backfeed breakers for a living.
 

junkhound

Senior Member
Location
Renton, WA
ac breaker either direction as far as tripping concerned,, if breaker has other functions such as remote reporting, varies with type.

dc breaker most only one way
 
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