Back Feeding Circuit Breakers.

Status
Not open for further replies.
R

Real_Bostonian

Member
Location
Eastern Massachusetts
We have an old Bryant panel, so we are using a listed Cutler Hammer circuit breaker to back feed the panel from the inverter output.

The breaker handle is labelled On/I and Off/O.

Article 690.10(E) states that "Circuit breakers that are marked "Line" and "Load" shall not be backfed".

The question is, does I/O mean the same thing as Line/Load?

If I read the code verbatim, the breaker is not specifically labelled Line / Load and should be able to be used. I can however see the inspector saying the input comes from the grid on the "I" side and input from the inverter enters the "O" side and might have an issue with it.

Any thoughts?
 
H

hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
The "I" and "O" on switch's and breakers are for the words "IN" "OUT" and is the internationally recognized wording for the term we use "on" "off" but the "in/out" has nothing to do with the location of the conductors feeding or leaving a breaker.

But this is where some inspectors do get the confusion from
 
G

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
jim dungar said:
Remember to employ a 'tie-down' method for a back fed plug-on style breaker.
Click to expand...
Not necessary. Per 690.64(B)(6) Fastening: "Listed plug-in type breakers backfed from utility-interactive inverters complying with 690.60 shall be permitted to omit the additional fastener normally required by 406.36(D) for such applications."
 
tkb

tkb

Senior Member
Location
MA
ggunn said:
Not necessary. Per 690.64(B)(6) Fastening: "Listed plug-in type breakers backfed from utility-interactive inverters complying with 690.60 shall be permitted to omit the additional fastener normally required by 406.36(D) for such applications."
Click to expand...

That is a strange requirement. I wonder why you wouldn't need a hold down for a backfeed breaker from an inverter?
 
J

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
ggunn said:
Not necessary. Per 690.64(B)(6) Fastening: "Listed plug-in type breakers backfed from utility-interactive inverters complying with 690.60 shall be permitted to omit the additional fastener normally required by 406.36(D) for such applications."
Click to expand...
oh.:slaphead:
 
Twoskinsoneman

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
hurk27 said:
The "I" and "O" on switch's and breakers are for the words "IN" "OUT" and is the internationally recognized wording for the term we use "on" "off" but the "in/out" has nothing to do with the location of the conductors feeding or leaving a breaker.

But this is where some inspectors do get the confusion from
Click to expand...

That's funny no one ever told that to me, I always just naturally thought it was a 1 and 0 like computer bit logic on or off.
 
H

hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
iwire said:
I sure would like to see a reference for it. :)

Seems odd a foreign standard would use English words.
Click to expand...

I guess it is time for me to learn something, and this is my best way when I get questioned:lol: Kind of a Yoda way of learning:p


I have no idea where or when I picked up that meaning over the years, but I do seem to remember old MDP's that would display the words "IN" and "out" as little flags depending if the breaker was racked in or out, and as we saw switches using the I and O over the years maybe I assumed this is what it meant?:ashamed1:

But after doing a quick search on it, I could not find anything supporting this view, I found this government PDF that agrees with many of you:

http://eetd.lbl.gov/controls/publications/switch5.pdf

But it does say the symbols are in fact a 1 and ? instead of the letters I and O so that shoots my theory:slaphead:
 
Last edited:
Status
Not open for further replies.
Top