# Are breakers directional?



## zinsco1 (Sep 1, 2010)

Wih regards to circuit breakers, i was always lead to understand they only work when connected line to line side and load to load side. I have recently been called in to do some evaluations on some solar systems installations and have been told the following, only breakers that are marked line side and load side are directional, other breakers not marked as such will work if connected either way. now this goes against all logic and years and years of installing circuit breakers, but i have to ask "is this true" ? Will breakers wired in reverse still function as an OCPD ? Almost every system i've looked at and reviewed the point to point connection drawings show the OCPDs wired in reverse " inverter output to a OCPD usually a fused disconnect then to the load side of a "plug in" style breaker at the sub panel. And i have to admit this has me going in circles and these are just the single phase systems, the three phase systems are connected the same with regards to the final point of connections only difference being most of the gear is commercial grade bolt on breakers. Any input would breatly appreciated. Thank you, zinsco1 (Guam, USA)


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## BBQ (Nov 16, 2010)

Not directional unless marked 'line' and 'load'.

It is very common to backfeed breakers.


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## 10492 (Jan 4, 2010)

Beats me, 

Zog, it's for you.


You at Anderson?


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## McClary’s Electrical (Feb 21, 2009)

zinsco1 said:


> Wih regards to circuit breakers, i was always lead to understand they only work when connected line to line side and load to load side. I have recently been called in to do some evaluations on some solar systems installations and have been told the following, only breakers that are marked line side and load side are directional, other breakers not marked as such will work if connected either way. now this goes against all logic and years and years of installing circuit breakers, but i have to ask "is this true" ? Will breakers wired in reverse still function as an OCPD ? Almost every system i've looked at and reviewed the point to point connection drawings show the OCPDs wired in reverse " inverter output to a OCPD usually a fused disconnect then to the load side of a "plug in" style breaker at the sub panel. And i have to admit this has me going in circles and these are just the single phase systems, the three phase systems are connected the same with regards to the final point of connections only difference being most of the gear is commercial grade bolt on breakers. Any input would breatly appreciated. Thank you, zinsco1 (Guam, USA)


 


Have you never installed a main lug panel and fed it with a breaker and hold down kit?


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## BBQ (Nov 16, 2010)

zinsco1 said:


> breakers not marked as such will work if connected either way. now this goes against all logic


Current is current and just like a fuse will work in either direction so will most breakers.

Here is some info from the UL General directory



CIRCUIT BREAKERS, MOLDED-CASE AND
CIRCUIT-BREAKER ENCLOSURES (DIVQ)



> Listed circuit breakers may be mounted in any position unless marked to
> indicate otherwise. If, however, the circuit breaker is mounted so that the
> handle is operated vertically rather than rotationally or horizontally, the up
> position of the handle should be in the ‘‘on’’ position.
> ...


The basic premise is that if we are not told we cannot .... we can.


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## alpha3236 (May 30, 2010)

If the system were DC, then I could see a reason for a directional breaker due to contact arcing. But in an AC system, there is no reason (in theory) for a breaker to be directional. I use breakers to "back feed" bussing in small panels (adding a main) all the time.


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## Zog (Apr 15, 2009)

Depends on the breaker type, but for a thermal magnetic MCCB, yes it will work. When CT's are used they will still work but the TCC's will be off a little. Some breakers will have 87 relays (Directional overcurrent) to prevent a backfeed. 

Another thing to keep in mind is there may be energized parts accesible that would not be normally energized for a tripped breaker when it it backfed. Had a frined get shocked by 480V's on a OD in a breaker that was backfed when he went to rack it out.


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## TOOL_5150 (Aug 27, 2007)

Zog said:


> Another thing to keep in mind is there may be energized parts accesible that would not be normally energized for a tripped breaker when it it backfed. Had a frined get shocked by 480V's on a OD in a breaker that was backfed when he went to rack it out.


Oh man.... Test before you touch!


~Matt


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## brian john (Mar 11, 2007)

alpha3236 said:


> If the system were DC, then I could see a reason for a directional breaker due to contact arcing. But in an AC system, there is no reason (in theory) for a breaker to be directional. I use breakers to "back feed" bussing in small panels (adding a main) all the time.


I have installed many large frame CB's in DC systems and never noticed any warning regarding this. In addition UPS manufactures cross line and load in CB's all the time, utilizing 3 pole CB's.


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## zinsco1 (Sep 1, 2010)

*Thank you*

I would like to say thank you to everyone who had the patience to post a reply. got to say no matter how long i'm in this business i still have the occasional brain fart. And this was one of those. could'nt get my mind around this. So again a sincere thank you to all of you. zinsco1 (Guam,USA.)


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## Zero point (Apr 24, 2011)

Gfci breakers cannot be backfed. I hear it fries them very fast.


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## oliquir (Jan 13, 2011)

Zero point said:


> Gfci breakers cannot be backfed. I hear it fries them very fast.


that's normal since there is an electronic monitoring system on them


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## brian john (Mar 11, 2007)

oliquir said:


> that's normal since there is an electronic monitoring system on them


 
I do not think that is true, BUT I could be wrong.

Volts go in and out, current does the same. Tell me why?


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## MDShunk (Jan 7, 2007)

brian john said:


> I do not think that is true, BUT I could be wrong.
> 
> Volts go in and out, current does the same. Tell me why?


I feel like I want to try it. I can't imagine why it wouldn't work. Having said that, you can't feed a (modern) GFCI receptacle through the load side terminals. I think they put special circuitry in them (now) to prevent that.


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## brian john (Mar 11, 2007)

MDShunk said:


> I feel like I want to try it. I can't imagine why it wouldn't work. Having said that, you can't feed a (modern) GFCI receptacle through the load side terminals. I think they put special circuitry in them (now) to prevent that.


 
Heck what's a GFCI cost a few bucks, I am game.


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## DCAC (Feb 11, 2011)

Save your money. Breakers have curved stipes of metal, copper, brass, invar, or whatever inside. Breaker trips due to the metal reacting to heat. These devices can mostly be back fed. GFCI's, weather outlets or breakers are bit more technical. They have an electronic board which monitors the flow of current. These devices cannot be back fed.


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## frenchelectrican (Mar 15, 2007)

Most of the Americian and European breakers are not a issue with backfeed function at all but very few will affect I know the GFCI { NA } may cause some issue ditto with AFCI but our RCD most case not too bad but delay responded if backfeed RCD. { espcally if you have line and netural reversed that merde did happend from time to time }

But for both Americian and European breakers if they say line and load then we have to follow it.

Merci,
Marc


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