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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 12:38 PM
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goldenboy1818

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Joined: 22 February 2011

Hi guys I have a problem here and I'm not sure what it is. It's a new large house all led spots and rf switching. Now what happens is as I turn on the switches one by one eventually it will trip the rcd. It does this on both rcds as two lighting circuits on each rcd. Have c type breaker in place and i know it's not overload as rcd tripping. Seems to me some sort of earth leakage maybe from these rf switches have you ever heard of this before?

Another thing with the microwave steam oven on it actually trips a bit quicker so say may only get 5 switches on instead of 8 so obviously a bit of leakage from the ovens. The ovens won't trip it by them selves but the lights will. Done ir test before switches wired in as these rf switches drag readings around so difficult to do that now without taking all switches apart. But like I say was fine before. I do have a surge protector in the board but it still does the same even with those isolated. Really confused on this guys struggling please help
 18 December 2015 02:05 PM
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mapj1

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Measure the earth currents with the loads on. Anything more than single figures mA should be treated as 'worrying'
Ramp test the RCD and see how many mA from L to E are needed to trip it, firstly with lights off, then a second time with as many on as it can stand.

And yes - RF controlled lighting will contain RFI filters, that almost certainly add some capacitors between L and E (and N and E and N and L) to keep the effects of conducted interference along the wires to a tolerable level for any one light, (note that the total may not be tolerable for many of them - but that's the way the standards are written - but its then the design authority's problem.)

At DC these insulate, at 50Hz some current will pass, at high Rf frequencies they look like a low value shunt, lowering the RF voltage between the lines at that point, and reflect most of the RF energy back to its source.
If the total circuit CPC current is much higher than 10mA , especially if light switches have metal faces exposed to touch, you may like to treat it like you would for a lot of computers, and wire it as a ring, or with a CPC loopback. ("high integrity earth")

I guess its now too late to do the lights on RCBOs in smaller groups so leakages don't add up to so much ?

Come back when you have the figures and hopefully more useful advice should be possible.

Also what make are the lights and switches- is there a maker's spec for earth leakage ?

-------------------------
regards Mike


Edited: 18 December 2015 at 02:14 PM by mapj1
 18 December 2015 02:30 PM
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goldenboy1818

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The switches are rf lightwave stuff in chrome.

I tried ramp test with no loads on board and was 21 ma with all loads on bar lights it's 18ma and with lights on it trips before I can even get a reading. Breaker hums with lights on. Obviously the new cooker must leak a bit as it trips a lot quicker with that on and the lights.

Is it a safety issue? Problem is both aurora and lightwave rf said both are compatible with each other but was no mention of limits or earth leakage
 18 December 2015 02:33 PM
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mapj1

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I tried ramp test with no loads on board and was 21 ma with all loads on bar lights it's 18ma and with lights on it trips before I can even get a reading


Can you try and re do it with just a couple of lights on ?
21mA sounds good, so it would be nice to know how much that margin is eaten away by each light that is on.

It sounds like probably is earth leakage, but we really need to know how much.

-------------------------
regards Mike
 18 December 2015 02:33 PM
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goldenboy1818

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Making a ring or anything now is not a option as very nearly finished house, but I could maybe henly block tails and add another small board with henly blocks for lights. Really appreciate this Mike been really stressed about this one
 18 December 2015 02:34 PM
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goldenboy1818

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Making a ring or anything now is not a option as very nearly finished house, but I could maybe henly block tails and add another small board with henly blocks for lights. Really appreciate this Mike been really stressed about this one
 18 December 2015 02:45 PM
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goldenboy1818

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Once the two lighting breakers are on even with the switches off it still trips two fast for a reading. The switches are quite weird and just being part of the circuit even when off seems to have the effect on the rcd tester. Without the rcd tester it will hold with breaker on and switches off but when I start turning them on eventually it trips the rcd out. Like say with the cooker on it trips much faster so that much also have some leakage too
 18 December 2015 02:58 PM
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mapj1

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Once the two lighting breakers are on even with the switches off it still trips two fast for a reading. The switches are quite weird and just being part of the circuit even when off seems to have the effect on the rcd tester



Ah. leakage from the input (non switched ) side of the switches then.

Oh Bother.

Or something like that but in your own words !

Can you measure CPC current - do you have anything with you that will detect a few mA of AC, like a super sensitive clamp meter, (or can you sneak a cheap AC reading multimeter in series - but don't open circuit the CPC with the power on - if you really have got a lot of earth leakage, then getting yourself in the way of it is really not good.)

-------------------------
regards Mike
 18 December 2015 03:11 PM
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goldenboy1818

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Hi Mike no sorry can't measure cpc current.only solution I can currently think of is to get a 5 way board with 5 rcbos for the five lighting circuits and Henley block tails
 18 December 2015 03:14 PM
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goldenboy1818

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Yes Mike must be leakage from input and output. Obviously increases with the input as eventually it will trip rcd itself with more switches turned on
 18 December 2015 03:24 PM
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mapj1

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Hi Mike no sorry can't measure cpc current.only solution I can currently think of is to get a 5 way board with 5 rcbos for the five lighting circuits and Henley block tails


That may well be enough. Problem is without actually knowing how near the edge it really is, its hard to say for sure how reliable it will be.

For occasional use, you don't need the most expensive meter in the shop,

A simple high resolution clamp meter with mA range

can be used to check this sort of thing. (if you need a Christmas pressie idea...)

You can measure CPC current direct , or put L and N through the pick up loop side by side like an RCD and marvel at the difference in those two readings for a few minutes until you remember there is a fraction that goes via the plumbing cross- bonding.

-------------------------
regards Mike
 18 December 2015 04:07 PM
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leckie

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Blimey that is cheap for a mA clamp meter, mine was about £300 I think.

Very handy bit of kit Goldenboy, you can clamp the line and neutral to the RCD and watch what happens as loads are added.
 18 December 2015 05:01 PM
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mikejumper

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Originally posted by: leckie
Blimey that is cheap for a mA clamp meter, mine was about £300 I think.

Looks very similar to the Di-log DL6505 which I think is about the same price.
 18 December 2015 05:04 PM
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Zoomup

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I have just ordered one, so I will report back when it arrives. I will compare it with my Japanese made one.

Bye,

Z.
 18 December 2015 05:18 PM
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mapj1

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I note that particular Di log one does not really do less than 10mA, at least according to specs. You really want the '06 not the '05 for the 1mA last digit for earth leakage stuff. - and it looks like it does DC clamp meter too, which may be good if you do much with vehicles or solar panels. (I don't have one though, I'm only looking at the on-line info)

I suggest like all 2nd tier/ less popular makers there is a risk that the quality control on the plastics and the weight and translation quality of the manual is duly reduced, but it will meet maker's spec, just, you are not paying extra just for a well known badge.

However, for a quick look and see 'is it getting better or worse' type of test, that you only do occasionally, there is not a lot of sense in spending a fortune, and you can usually live with a bit of a fruit machine effect on the last digit, so long as its stable for the test duration.

Same way as you don't buy expensive screwdrivers to stir paint tins.

-------------------------
regards Mike


Edited: 18 December 2015 at 05:27 PM by mapj1
 18 December 2015 05:52 PM
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goldenboy1818

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By the way the earth has no actual connection to the light switch it's just choc blocked or wago. They are double insulated even chrome so no earth connection
 18 December 2015 05:59 PM
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John Peckham

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I have the Robin K2413 Earth Leakage clamp meter and the Megger DCM300E. The Robin has a really big set of jaws that is useful for getting around 3 phase circuits and the Megger for getting around conductors inside DBs where the jaws of the Robin are to large.

Both very good pieces of test kit but expensive. The Robin is no longer made but Kewtech make a re-badged version.

Goldenboy

It would appear the cumulative leakage currents are tripping the RCD/RCDs I would guess but would want to use an earth leakage clamp to prove it. If it is earth leakage then you will have to divide the circuits over more RCDs or RCBOs. I would say you may have to remove one or both RCDs and replace the MCBs with RCBOs.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 18 December 2015 06:00 PM
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mikejumper

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Originally posted by: mapj1
I note that particular Di log one does not really do less than 10mA, at least according to specs.

My mistake.
It should have read DL6506 which has a: 1mA - 80A range

Perhaps better still the DL6518 which has a 200mA range with a resolution of .01mA.

I don't own any of this kit so can't say whether it's any good or not.
 18 December 2015 08:36 PM
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WiredScience

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Originally posted by: goldenboy1818

By the way the earth has no actual connection to the light switch it's just choc blocked or wago. They are double insulated even chrome so no earth connection


Sounds like you can rule out leakage due to the filters in the switches then. Are they in deep boxes? Is it possible that you've trapped a wire somewhere?

I'm guessing the IR test was done with switches linked out - is it possible to re-test line/neutral to earth, maybe at 250V to gain some confidence that all is well?

Another safe option, if you have a suitable multimeter, is to measure the capacitance lives to earth, get your calculator out, and work out the likely leakage at 50Hz.
 18 December 2015 09:32 PM
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goldenboy1818

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Yes ir was done with switches linked out.

Thing is its the same on the second rcd with the other two lighting circuits, as more switches turned on it eventually trips tye rcd. Definitely seems like leakage but I don't know how

Also these switches make some of the led spots buzz, once changed for a normal switch it is fine
IET » Wiring and the regulations » Real problem guys really need some help?

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