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Topic Title: Real problem guys really need some help?
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Created On: 18 December 2015 12:38 PM
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 18 December 2015 09:52 PM
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Fm

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Joined: 24 August 2011

How many led fittings per circuit?
Does the manufacturer recommend a max number per circuit?
 18 December 2015 09:58 PM
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goldenboy1818

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Only about 60-70 max. So only max 700watt but it mist be tied in with leakage as with the cookers on it trips with less lights being Turned on so obviously the cooker has some leakage so it gets to the 30ma quicker. Really bothering me this problem can't see the full reasoning
 18 December 2015 10:20 PM
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OMS

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Are you sure you don't have a N-E fault on somewhere - increasing load that fires both RCD's suggests that it may be present (or you really do have an awful lot of leakage current)

Regards

OMS

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Let the wind blow you, across a big floor.
 18 December 2015 10:29 PM
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goldenboy1818

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It doesn't fire both at the same time, it's just the rcd relating to the light circuits I'm switching on. So if I'm turning on lighting circuits on rcd 1 it eventually trips rcd 1 and if the lighting circuits on rcd 2 it eventually trips rcd 2 as I'm switching lights on. Really stuck here praying for someone to give me that magic moment. Anyone know of these lightwave rf switches leaking to earth, I mean does it have to leak to earth to trip the rcd of just play with the voltage somehow as I know lightwave stuff works in some strange ways
 18 December 2015 10:35 PM
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aligarjon

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i am not familiar with the switches, can you not bypass them temporarily to eliminate any problem with the lights and then maybe introduce them one at a time.

Gary

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Specialised Subject. The Bleedin Obvious. John Cleese
 18 December 2015 11:51 PM
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stateit

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Originally posted by: Fm

How many led fittings per circuit?



Originally posted by: goldenboy1818
Only about 60-70 max.


My understanding is that LED lights have a huge startup current - about 40x (I stand/sit to be corrected)

I only ever fit about 12 max per switch.

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S George
http://www.sg-electrical.com
 19 December 2015 12:00 AM
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mapj1

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ah you did not mention double isulated.
assuming no mistake, it cant be Y capacitors, as there is no CPC to connect them..
So if you lift the cpc back at the board, do the lights go out?

can you measure NE resistance ? No chance of lighting neutrals returning via the wrong rcd compared to the live outbound?

-------------------------
regards Mike
 19 December 2015 07:30 AM
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goldenboy1818

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Yes stateit we have a c type breaker in place to allow for start up.

What take out the cpc at the fuseboard to see if it trips still? Surely I know it's going back to earth which is why is tripping rcd. Must be some earth leakage as it's tripping quicker with oven on. Also I could expect a fault but where it's doing the same thing across the four lighting circuits on two different rcds it seems unlikely.

I can measure neutral to earth resistance it is lowered massively with all these switches in though, when I done the first test I had to test every individual wire with no switches on and was fine.

Rcd set up seems fine all neutrals to correct places. If neutral on wrong rcd thought it would trip straight away with load, this allows me to turn a load on before it trips.

So weird, bad sleep thinking about this
 19 December 2015 07:52 AM
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leckie

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Goldenboy

I don't know about Lightwave stuff but I think my approach would be as follows.

1. Speak to Lightwave and ask them about any earth leakage problems, and also the buzzing lamps. Ask about the maximum amount of lamps per switch and compatibility of lamps/fittings.

2. I think I would do what you have suggested and fit a dedicated lighting board with individual RCBO's.

3. I would invest in a mA clamp meter that can measure down to single digit mA values, very handy for lots of other problems as well as this particular problem.

Now some general thoughts:

I am unsure how the switches could have earth leakage if they are double insulates unit. If you replace the switches with standard switches does the RCD still trip?

I assume that the you have checked the N-E insulation values?

I assume there is no possibility of a borrowed neutral?

I assume there is no possibility of a low IR value between the neutrals of each circuit? Or even the live from one circuit to the neutral of the other. No necessarily a borrowed neutral, just a low IR. I would be tempted to test for this. If somehow the neutrals were crushed together or something similar there might be some current shared that could unbalance RCD's .

I assume that these switches are just a direct replacement for standard switches? You say that if you turn on switches one by one, eventually the RCD trips. (This is where the clamp meter would come in handy around the Line and neutral).

Try this:
If you turn on the switches one by one, and as each switch is turn on, measure the current in the line and then the neutral individually through the RCD at the consumer unit, the value should be the same. A standard clamp meter would do for this. If it's not then you could have a low IR either to earth or from neutral to neutral. Turn on the next switch and do the same again until you get to the point where the RCD trips. Then replace that switch with a stared switch, reset the RCD, turn it back on, does it still trip? Measure the current in the line and neutral if you replaced the of the switches with standard switches does the RCD still trip? You could do this for a complete circuit. If at any point the L or N current becomes unbalanced, i.e. not equal, you can investigate that section.

Easiest solution? Fit newcRCBOMboard and buy a mA clamp meter
 19 December 2015 08:22 AM
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goldenboy1818

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It seems to definitely be some sort of earth leakage as the more switches that are turned on and in no particular order it trips the rcd so it's the accumulation of something. Lots and lots of switches and 5 lighting circuits so difficult to swap all switches to try. I mean I can put one complete circuit on and it will hold but as I go further with the second circuit on the same rcd it eventually trips. If i do this in reverse order it's the same. And if I do the same process on the other rcd side it's the same. Wouldn't rcd trip straight away if borrowed neutral etc rather than letting me turn loads of lights on?

I do have say a two gang rf switch on some.floors that may have three cores from two different circuits on them. They are not linked in separate neutrals and earth but I wonder if they would create somesort of leakage to each other? I don't think they are on separate rcds though
 19 December 2015 08:38 AM
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Fm

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You advised on the make of switch , but what type of fitting/ lmp is used. Manufacturer make and model please
 19 December 2015 08:41 AM
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goldenboy1818

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Aurora M10 did check on compatability of switches and leds before fitted and that was ok. He does have some led strip Phillips on one of the lighting circuits but only on one circuit not all of them, the majority is aurora m10s.
 19 December 2015 08:43 AM
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goldenboy1818

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Is it possible for these lightwave rf switches that even though they are not connected to earth to play with the voltage enough to cause rcd to trip. They have led/neon on the light but no neutral or earth connection, wondered could tge accumulation of these cause rcd to go?
 19 December 2015 08:47 AM
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leckie

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If there was a borrowed neutral it would have to be borrowed from a circuit on the other RCD. It would trip once a load was switched on that goes down the borrowed neutral. Same as would happen if there was a N-E fault. If there was a low IR between a neutral from one RCD and another that would trip once the RCD was seeing a sufficient imbalance.

Have you tried turning on the lights with one RCD on and the other one off? Not just the mcb's, the RCD so the neutral was isolated. If the leakage was going down the other neutral, it wouldn't be able to if you isolated it.

I think finding the problem without dismantling too much stuff is only going to be feasible using a earth leakage clamp meter. If the job is urgent and needs sorting before the Xmas break it might be worth you sourcing one asap. That won't cure the problem, it will just help you diagnose it. The rcbo board idea will give you a greater chance of success but I would want to know where this leakage current is going.

If you isolate each neutral by trying with only one RCD on at a time then it must be going to earth. So if you measured 20mA around the RCD L/N you could then measure around each circuit L/N on that RCD and see if it being shared across each circuit.

Edited: 19 December 2015 at 08:59 AM by leckie
 19 December 2015 08:53 AM
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leckie

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I would speak to lightwave as well.
 19 December 2015 09:02 AM
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goldenboy1818

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Could I do a ir test between two neutral bars then with rcds off to see if it's leaking to the other neutral?
 19 December 2015 09:04 AM
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goldenboy1818

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If it was that neutral to neutral how could I track that down to rectify?
 19 December 2015 10:02 AM
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leckie

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Have you tried leaving one RCD off and then turned on the lights on the other RCD controlled circuits? Try that first. If that stopped the fault then that would confirm there is a N to N fault.

Then if the problem persists you could IR between the neutral bars and it should give a high value. If it's low, it could be a N-N faults or, if there were N-E faults to both sides it could be reading through through both neutrals to earth. Thinking it through a bit more, if there were N-E low IR faults to both RCD supplied circuits then, even with one of the RCD's turned off, if there was also a N-N low reading it could still trip! To find problems like that involves lots of disconnection of the neutrals from the neutral bars, cpc's, etc. That's why it's a lot easier with a clamp meter, you can see what's going on without too much dismantling.

Get on Google, find somewhere near you that stocks one that goes to low mA, and buy one. It will save you a world of pain and you will use it a lot. And speak to lightwave on Monday if they are open!
 19 December 2015 10:57 AM
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goldenboy1818

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Would the clamp meter suggested earlier be suitable, really appreciate this advice leckie, going out my mind was meant you be finished yesterday for Christmas with the family then this happened so I'm absolutely gutted right now
 19 December 2015 11:07 AM
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goldenboy1818

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If it was a n-n fault wouldn't it trip with any additional load not just the light switches going on as essentially all the neutrals are linked at the board?
IET » Wiring and the regulations » Real problem guys really need some help?

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