Wiring question about Schneider RCB

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  #1  
Old 02-09-15, 12:14 AM
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Wiring question about Schneider RCB

Can someone help me figure out how to wire this thing. From what I figure. Neutral and Live wires go at the bottom and the load Neutral and Live wires comes out the top. What about Earth? How does this thing detect an earth fault condition.

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  #2  
Old 02-09-15, 12:45 AM
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Neutral is your earth connection.
I couldn't find any details in wiring that particular breaker.
 
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Old 02-09-15, 03:36 AM
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I didn't get what you were saying about Neutral being earth. Do you mean that it does not need an earth?

There's a wiring diagram on top

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Old 02-09-15, 04:54 AM
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This appears to be some sort of GFCI breaker, since it has a trip button, and a denotation of 30 mA. It also appears to open both neutral and hot at the same time. GFCI needs only a difference between the hot and neutral to trip. No ground (earth) is required. You are in Pakistan, so we really don't deal with this type component everyday.
 
  #5  
Old 02-09-15, 06:02 AM
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Electrically this Residual Current Device circuit breaker (RCCB) is connected up in the same manner as a ground fault circuit interrupter breaker in the U.S. There is of course the physical difference in how the breaker fits in the panel. Sometimes there is no live fin underneath and both the hot and neutral line side connections are made using wires.

RCD works in the same way as GFCI although I think the two specific terms refer to devices with different earth fault thresholds, need to look that up later.

RCD/RCCB/GFCI provides near perfect protection from electrocution provided that the earth fault threshold is low enough. Although the device trips (should trip) if a fault to an equipment grounding conductor (earthing wire) next to and/or attached to the RCCB unit occurs, the earth fault condition being guarded against is from something energized by the protected circuit (load side) through a person's body and then through some possibly convoluted path to ground such as through a moist concrete floor.
 

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  #6  
Old 02-09-15, 06:20 AM
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So I just need to wire neutral and live and I am good to go? From what I understand if there is a ground fault, then it will trip because it will detect a current imbalance between hot and neutral.

Found this from the product brochure...

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  #7  
Old 02-09-15, 06:45 AM
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Hi

Its an RCBO - Residual Current Circuit Breaker with Overprotection.

It detects imbalances between the Hot and Neutral (ie either to the Ground or to the Ground via a person..) and Overprotection (ie in your case more than 16 amps).

Please ensure that it is an RCBO if you plan on installing it without a MCB (Minature Circuit Breaker - not main!). Note that is more typical to see just an RCD in Europe installations and then individual MCB's for each circuit. (In RCD there is no over protection just residual protection). US GFCI's are RCBO's in European speak - they include both Residual and Overprotection in one device.

In Europe and Asia the normal practice is not to check an individual circuit but to protect a selection of circuits within the panel - how many depends on local rules. Typically loads are spread across those requiring protection and those not. Also its typical to have two of these installed - mainly so that when triggered the lights stay on for one circuit!

I think you'll find that the top is the inlet side (ie Live) whilst the bottom is the load side.

The key difference is that because this device is normally installed prior to the bus bar it takes wire as an input although it is possible to install it with a bus bar by locating the tab on the bus bar in the input side (more relevant to Industrial installations).

Here is a good linke that outlines the basics around UK panels.

DIY Wiring a Consumer Unit and Installation - Distribution Board- Wiring Diagrams

If you are in Pakistan then I would think the local practice would be similar / based on the UK practice. But your mileage may vary. If you can post a photo of the distribution power panel I can see if I can work it out.

Thanks

Mick999
 

Last edited by mick999; 02-09-15 at 07:47 AM.
  #8  
Old 02-09-15, 10:52 PM
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Mick,

Thanks for the link, it helped me understand things more clearly. I will explain how I intend to use this RCD. I have a main distribution board on the ground floor of my house. This RCD is going to be installed in a separate distribution board in the basement. The live wire that goes into this RCD
comes from the main distribution board and it is protected with an MCB.

The two devices that will be connected to this RCD include a potable water pump and a sewage pump. The reason I put this RCD in a separate box is that the neutral wire is shared, I cannot isolate the neutrals coming to both the circuits that I intend to protect with the RCD, and as far as I know, a shared neutral will trip the RCD. I may be wrong about this- need an expert opinion on this. If I can install this in the main distribution board, I'd rather do that instead of having a separate distribution box with dedicated wiring to both circuits. The other thing I am not sure about is the inlet and outlet of this RCD. Are you sure the live wire goes on top? I had figured it would be the other way around.
 
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Old 02-09-15, 11:28 PM
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Sharing a neutral comes into effect when you are running two hot wires thru two breakers.

You are using one circuit to operate a water pump and a sewage pump. You can have more than one device or receptacle on a fault type breaker.

As far as I can see based on every wiring diagram I could find.... the breaker is fed from the top.
 
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Old 02-10-15, 01:38 AM
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Ok. I guess I'll wire this thing up and test it first before installing it in the distribution panel
 
  #11  
Old 02-10-15, 05:18 PM
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As PJMax said - put the RCD in the main panel.

Do you have a single circuit running to the basement from the main panel ? If so I'd just put the RCD in main distribution panel and wire that circuit into it.

You can run both the water and sewage pump on that circuit if the total amps don't exceed 16.
 
  #12  
Old 02-10-15, 10:55 PM
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I don't have a single circuit to the basement from the main panel, to the water/sewage pump there are too many things connected to that circuit, which is why I was thinking of putting this in a separate distribution panel. Having only two things connected to the RCD will also simplify the process diagnosing a fault. The combined load is well within the 16amp rating of the RCD.

I ran the sewage pump on the RCD yesterday and everything seems to be working fine The test button trips it just as it should. I plan to put it in a distribution box over the weekend. Thanks to everyone for their help.
 
  #13  
Old 02-11-15, 02:46 PM
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Sorry, but a sewage pump is one of the last things I'd put on a RCD. Is this a code requirement where you live? Is it a dedicated circuit with no user available receptacles?
 
  #14  
Old 02-11-15, 06:08 PM
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In Europe Regulations - I seem to recall that if you can't achieve a disconnection time of 5 secs an RCD is required.

Not sure where whiteangel actually is however!
 
  #15  
Old 02-12-15, 01:35 AM
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Mick, I'm in Pakistan and we follow the British regulations.

Normally, one wouldn't need to put a sewage pump on an RCD, but in my case I have to because of two reasons. The sewage pit has a metal cover and the pipe that pumps out the sewage into the municipal drain is metal as well. Bad choice of material on part of the contractor who built the house. My old sewage pump was leaking current into the drain pipe and the metal cover. I have a new pump now and so I am putting it on an RCD to prevent this sort of situation from happening again.
 
  #16  
Old 02-12-15, 06:46 AM
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I have a new pump now and so I am putting it on an RCD to prevent this sort of situation from happening again.
The RCD problem with motors is a possible false trip at start up, even if the leakage current is low. You can get RCD's with higher than 30mA trip point, and I would try to use one of those.
Of course, the traditional FIX for eliminating leakage into piping is to bond the metal items to ground. Why won't this work for you? You will not be happy with this circuit tripping off occasionally

How often are deep jet well pumps run to a GFCI//RCD??
 
  #17  
Old 02-12-15, 09:42 AM
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I wasn't aware that motors could cause false tripping of RCDs. Does it have something to do with inductive loads?

I did do a test run with the sewage pump and it didn't trip the RCD, so I am hoping it won't happen. The sewage pump only runs about once every couple of weeks, when the pit is full. If it does cause false tripping, then I guess I'll need to consider the alternative solutions.
 
  #18  
Old 02-16-15, 01:11 AM
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I installed the RCD in a separate distribution box in the basement over the weekend. After wiring everything up, I tested the RCD using the test button and it would not trip. Anything plugged into the socket connected to the RCD would cause it to trip. But pushing the test button on the RCD would do nothing. Strange.

Since the RCD was working perfectly when I tested it previously, I though may be the wire is the source of the problem. I replaced the entire length with a different wire then everything started working perfectly. Couldn't figure out what the problem was with the original wire.

Thanks to everyone for pitching in with their suggestions.
 
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