408.16(F) question (backfed breaker)

[Unregistered]

This article/paragraph talks about overcurrent protection devices that are backfed and how they must be securely fastened. I've never understood the term "backfed" in this context - is this referring to a "main" breaker on a non-service (sub) panel or something else? Why is this important?

[Speedy Petey]

I don't have my handbook here so I can't give you the laymans interpretation. I can give you my opinion.
Have you ever seen a C-H 100 amp main panel? The one with the 2 pole 100 feeding the buss just like all the other branch breakers. This always has a screw through the breaker secureing it down. This is in case the breaker comes loose the hot breaker is not flopping around. In a true main lug panel there is no likely chance of live parts coming loose.
There are also main lug conversions which stab onto the buss. These always have screws also.

[Unregistered]

OH...

Now it makes sense - it's the LOCATION of the breaker. Sure, you wouldn't want to pull it not knowing it's been energized from somewhere else...

thanks!

[Wgoodrich]

You are getting the picture of concern, however I suspect you are missing the use of the term back fed. In almost all occasions back feeding a breaker is forbidden because of the concern you are speaking. If that breaker came out of that mounting position into your hand then you would still have an energized breaker in your hand. Most always a breaker is fed from teh power supplied by the buss bar of that panel. The term back fed depicts that power in this back fed breaker is coming from the normally load side of the breaker feeding power to the buss bar.

Speedy Pete is correct about the back fed breaker used as a main breaker in a main lug only panel must be secured to the panel to avoid that hot breaker to land in your hand by mistake. He mentioned they have to be screwed into place. Some breakers though have a plastic locking bracket that locks that breaker in place as a convertable panel from Main lug only to Main service rated panel installing that back fed breaker then locking it in place by the screw or a plastic bracket supplied by the manufacturer.

There are some main lug only panels out there not listed or labeled to be converted because they have no means to mount and secure a back fed main breaker in that certain panel.

Hope this helps

Wg