# Question about Differential breaker installation



## peloflex (Jan 18, 2013)

I am putting together a PLC training module for the school I work for. The module requires both 3PH and 1PH circuits combined. My question is, at which point should I get my 1PH lines from the 3PH so I don't create an unbalanced load that would trip the 3PH differential breaker?
The 3PH circuit is to be used for working with AC motors and the 1PH is for powering the control part. please refer to my sketch to better understand my question. 










I am having some difficult loading the picture from the sketch I have made, I hope this works. 
Thank you in advance


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## Wirenuting (Sep 12, 2010)

peloflex said:


> I am putting together a PLC training module for the school I work for. The module requires both 3PH and 1PH circuits combined. My question is, at which point should I get my 1PH lines from the 3PH so I don't create an unbalanced load that would trip the 3PH differential breaker?
> The 3PH circuit is to be used for working with AC motors and the 1PH is for powering the control part. please refer to my sketch to better understand my question.
> 
> I am having some difficult loading the picture from the sketch I have made, I hope this works.
> Thank you in advance


No picture showed up..
How large is this trainer?
What about a transformer for the single phase load?

It sounds like your building equipment and not installing it. The rules are different. 
Stop by the intro thread and say hi.. Give an explanation of what you do for a living. Sounds like your not an electrician.. 

Welcome to ET..


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## peloflex (Jan 18, 2013)

The training module is about 4ft wide by 2ft tall, here I am trying to post the sketch once again. 

http://img132.imageshack.us/img132/8665/img20130118100906.jpg


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## peloflex (Jan 18, 2013)

here is my intro:


http://www.electriciantalk.com/f3/greetings-lima-peru-48959/


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## Wirenuting (Sep 12, 2010)

I don't understand the differential breaker.


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## Big John (May 23, 2010)

Wirenuting said:


> I don't understand the differential breaker.


 Almost sounds like he's talking about a Peruvian GFCI.

_Peloflex, _is this breaker for personnel protection?


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## peloflex (Jan 18, 2013)

Affirmative, a breaker that only remains closed as long as the load on all legs (3 or 2) is balanced out. meaning if something (could be a person) causes a leak or a drop in one of the legs, the breaker opens up preventing further damage. 

http://www.directindustry.com/prod/...al-current-circuit-breakers-54121-828171.html

We recently had an incident where a student was saved by one of these devices.


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## micromind (Aug 11, 2007)

If current only goes between phases, and not to ground, it shouldn't matter if they're balanced or not. The breaker sees power going out one of the phases and compares it to power coming back in on the other two. Which phase it compares changes 60 times a second. 

Is there a neutral involved?


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## Deep Cover (Dec 8, 2012)

As long as you are tapping single phase off the 3 phase before the diff breaker, the diff breaker will not see the load of the single phase.

edit: If you tap off before the diff breaker, that tap will not be protected by the diff breaker.


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## Aussielec (Apr 1, 2012)

A three phase "unbalanced system" has nothing to with the operation of an RCCB, at all. 

Where you have installed it in your picture is where it should be assuming you want to protect the control gear aswell.

The RCCB sensors what's coming in compared to what's going out of the circuit. While the RCCB measures current inbalance between conductors it is a different sort of inbalance compared to three phase system inbalance.


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## chicken steve (Mar 22, 2011)

These RCCD's operate much like our GFCI's, or AFCI's 

Unfortunatley, we are not privy to any sort of _'enhanced main breaker'_, as i am finding much of the rest of the world subscribes to

~CS~


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## BBQ (Nov 16, 2010)

chicken steve said:


> These RCCD's operate much like our GFCI's, or AFCI's
> 
> Unfortunatley, we are not privy to any sort of _'enhanced main breaker'_, as i am finding much of the rest of the world subscribes to


And why do you find that unfortunate?


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## chicken steve (Mar 22, 2011)

In discussing and learning the differences bettween our electrical systems BBQ

I find our Euro _(and now S. American)_ contingents subscribe to, and employ a system utilizing personal & equipment protective _enhancements_ that can be backed up with an electrical _rationale'_ 

Juxtaposed to our rather isolated and unique system in the states, which seems predicated more on marketing forces, as opposed to reason

~CS~


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