E.L.C.B.s

[jj4091]

I have had an elcb protecting the garden supply(pump, lights etc) without problem for the last 10-11 years, which has now started nuisance tripping. I have read that this is common with elcb's but given it previously being ok, I wondered if it may be a sign that it is on it's last legs. I have insulation tested all the circuits which showed no problems & the fish in the pond seem happy enough, but I have no means of actually testing the elcb unless someone can tell me how to do it with a megger ( very old) or a multi meter( the only testers I have access to these days). Thanks.

 

[Spark123]

If it is an old Voltage Operated ELCB then it should be replaced on sight!
If everything meggers out OK then I'd try another RCD just to see if that solves it.

 

[ericmark]

There are two types of ELCB the v-ELCV now no longer used and c-ELCB I will assume the latter. The testers for the latter test on positive and negative cycle separately and also record the time.
However there is no reason that a simple go and no go tester could not be made for a 30ma unit it should not trip on 15ma it should trip on 30ma and should trip within 40ms at 150ma the latter you can test but the first two you can.
However not too expensive to hire the testers and I am not too keen on instructing a DIY person on how to make a tester in case he gets it wrong and injures himself however if you are more than a DIYer then you should be able to work out resistor sizes without my help.
I have noted that although a RCD will pass using the proper tester it will still nuisance trip. Changing it however does often cure the problem so I would tend to just swap it and see how it goes.
If old v-ELCB then ditch and change for RCD ASAP. They will have an earth connection where new type has no connection to earth.

 

[RF Lighting]

Although, the new current operated type may have a functional earth wire.

If you are unsure which type you have, either post up on here everything that is written on the front of the device, or better still, post a photo of the offending item.

 

[ericmark]

Although, the new current operated type may have a functional earth wire.

If you are unsure which type you have, either post up on here everything that is written on the front of the device, or better still, post a photo of the offending item.

Thanks for pointing that out. I did consider saying something but only seen them on RCBO's to date.

Of course there are many types of RCD

Untitled

• ericmark
• 6 Dec 2008
• 34

these are very good where you can't afford a power failure but once you see the price tag I would think most people would find it cheaper to insure.
If my father dies before my mother I would fit one as in a wheel chair she can't access to consumer unit but for most things a UPS would be better.

 

[Spark123]

I haven't come across those auto test RCDs yet - how do they work? There is a pic of a man with a phone on them - does that mean they can be reset remotely? Or when they trip do they automatically re-close? If they do then it sort of defeats the object of having an RCD.

 

[ericmark]

ReStart with Self-Test can be installed in the electrical enclosure of the home, and guarantees the total safety of the family and the building. ReStart with Self-Test is the only device that automatically reactivates the current only after having checked the good working state of the system, and every seven days it carries out the test of the residual current circuit breaker, without removing the voltage from the electrical system.
From memory over £230 saw them on IET web site also here as well. A pdf Gives part numbers and found this picture

Gewiss RCD

• ericmark
• 30 Jun 2009
• 1

But can't find the UK outlet. This guy has them on his web site.

I have never used one but good way to stop argument on RCD tripping "Yes I can fit it by fitting one of these will you pay for it" I think you can guess answer.

 

[jj4091]

Thanks to all for the replies: Eric, you are correct as a retired spark it would be possible to build a tester but I may as well just buy an rcd & place the old unit when you consider the time factor. I hoped it may be possible just with the gear that I currently possess. Rf lighting, thanks but I do not think you will recognise a photo of the item, it is a generic American supplied device with no identifying features that we used to use when I was working. Spark123 It is indeed a voltage operated device, but not having been at work for quite a while now I did not realise they were considered so un-safe. Could you enlighten me please?

 

[ericmark]

The voltage operated ELCB can be made ineffective by parallel earth paths and this was quite common so they have been in the main replaced by current type.
The new regulations require a 30ma unit which will at 5 x 30ma work within 40ms to be used on all socket outlets at under 20A and all items in a bathroom plus any cables buried less than 50mm in a wall unless special cables like Ali-tube are used.
This has resulted in the main in all circuits being protected by a 30ma RCD. There are a few exceptions sockets marked for special use like fridge for example.
Also the splitting into circuits it now includes to reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation. This means in most cases we can't use a single RCD.
Two methods are used the cheap option with two RCD's protecting everything and second it to used RCBO's and as a result the units are much more available than in the past including units which convert MCB's to RCBO's

 

[Spark123]

Bit of bedtime reading:
http://www.theiet.org/publishing/wiring-regulations/mag/2005/15-insp-test-rcd.cfm?type=pdf

 

[jj4091]

Thanks to you both. Spark123 , having read your link I now think I may be mistaken in thinking that it is the voltage operated type as we were still installing them long after 1981, as there are no ratings or identyfying marks on it it is difficult to tell what it is, plus the old memory plays tricks as you get older . On the good news side after playing up for four days before I made the post, it has now not tripped for for 72 hours so I think I will wait & see what happens.

 

[JohnD]

I am a bit puzzled that you seem to be assuming that the reason for your RCD tripping is that the RCD is faulty

With it feeding wet outdoor circuits, I would have thought a much more likely cause would be that there is in fact an intermitted leakage.

 

[ban-all-sheds]

If it's caused by water ingress somewhere, I would have thought that doing an IR test straight after a trip would not "show no problems"?

 

[Spark123]

One telltale sign of a Voltage operated ELCB is that there will be two earths going to it in separate terminals - one being the electrode or means of earthing and the other being the installation protective conductors.

 

[jj4091]

Spark 123, thanks, that confirms it then as there is just the just live netral & 1 earth connection in & out of the device plus test & re-set button. I never had the time, the opportunity or any reason to question the workings of them, they came as a sealed unit in a clear plastic bag, ready cabled & we just connected them into circuit, never had a problem with them & every body just called them ELCB's rather than RCD's. Just shows you should not take things at face value John D, yes obviously water ingress was my first thought, but as BAS says nothing showed up when I meggered the pump & wiring(the only device in use at the moment, no lights being used) there was no abnormal restistance anywhere. Also as I said in original post the fish are perfectly OK &, unless I am mistaken about this aswell as the breaker, they are far more susceptable to electric shock than we are. I was oringinally looking for advice on how to test the breaker to eliminate it before looking elsewhere, but thanks anyway