Backfeed

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It can mean the panel is fed thru what might normally be considered a "branch breaker". It is fairly common to use a Main Lug panel, install a breaker as if it were going to feed a branch circuit, but supply power to the panel by "backfeeding" to that breaker. When it is wired in that manner, the Code requires a "breaker retainer" to secure the breaker if it is a "plug-in" breaker (NEC408.36{D} ).
 
When someone tells me there is a "back feed" refering to gear or switchgear, that tells me although the power to this gear or switchgear is turned "OFF" there is still another source of power supplying some sort of power to sections of that gear or switchboard!
 
Backfeed usually means to me an illegal generator hookup. Someone will install a range or welder receptacle from the panel and then plug in a portable generator to feed the panel, hopefully remembering to turn off the main. Of course, it can be done properly with the right lockout, but the term backfeed is not usually used then. But, as mentioned, backfeed is anytime a panel is fed through a branch circuit rather than from the service.
 
Sounds like their are more then one use of the term "back feed".
You can back feed an outlet. Or you can wrap it around the screws.
 
jargon

jargon

Buck Parrish said:
Sounds like their are more then one use of the term "back feed".
You can back feed an outlet. Or you can wrap it around the screws.
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Do you mean 'back-stab' as in a poke home sw or recep? Back feeding power through a receptacle to trouble shoot a dead circuit is what comes to mind for old timers like me. rbj
 
Sounds like their are more then one use of the term "back feed".
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Kind of like "low voltage", it depends on he context.

To me it means "being fed from somewhere other than it's normal source"
 
or Abnormal Source

or Abnormal Source

220/221 said:
Kind of like "low voltage", it depends on he context.

To me it means "being fed from somewhere other than it's normal source"
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Like an improperly installed solar array without isolation. The lineman really love it. rbj
 
If one phase goes out on a single phase system. Some times the other phase will energize the other one. This is back feed through the elements, or coils in your 240v equipment.
 
Consider this example of a "BACK FEED":
Typical office building with a single common transformer feeding two low voltage panels. One panel feeds the 120/208 3 phase circuits to the north end of the floor and the other feeds the 120/208 3 phase circuits in the south side of the same floor. Somewhere around the midpoint of this floor, someone ties circuit one(a black #12) fed from the south panel to circuit one(a black #12) fed from the north panel--by mistake in a junction box. During a buildout of the south side of this floor, the south panel is turned "OFF" ! But the panel is still energized on "A" phase via the #1 circuit and "backfeeds" ALL the "A" phase circuits due to a "BACKFEED"........
 
charlietuna said:
Consider this example of a "BACK FEED":
Typical office building with a single common transformer feeding two low voltage panels. One panel feeds the 120/208 3 phase circuits to the north end of the floor and the other feeds the 120/208 3 phase circuits in the south side of the same floor. Somewhere around the midpoint of this floor, someone ties circuit one(a black #12) fed from the south panel to circuit one(a black #12) fed from the north panel--by mistake in a junction box. During a buildout of the south side of this floor, the south panel is turned "OFF" ! But the panel is still energized on "A" phase via the #1 circuit and "backfeeds" ALL the "A" phase circuits due to a "BACKFEED"........
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Backfeed (Backfed, backfeeding) is an important concept to understand. Above is a great example of "careless mistake" backfeed. Understanding this concept improves safety and can possibly help with installs.

I wish I had time to contribute another backfeeding scenario like charlietuna's. I'll contribute this, however:

Panel L1 is overloaded. A general purpose circuit (we can call it ckt L1#1) is deleted from L1 and assigned to Panel L2 which has a spare 20A breaker in space #7. The foreman asks you to, "Remove the old homerun from panel L1 and backfeed the remaining existing circuitry from Panel L2#7."

In reality you are "refeeding" not necessarily "backfeeding" but that is an example of how this generic term can be used in the field.
 
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