Confusing tripping problem

[MickM9]

Hi guys, hoping someone on here can give me a clue whats happening here.

Basically my RCB is tripping out intermittently, it can happen at any time of the day or night without me doing anything.

HOWEVER, I can create a couple of scenarios where I can manually make it trip and was wondering if someone can give me a clue as to what might be happening.

I have recently installed some new pond pumps and filters to the garden pond and the first scenario where I can make it trip is by unplugging all 3 plugs (pump, filter, UV light) and replugging them, this WILL trip the switch.

BUT, if I leave the plugs in and reset the trip switch they will work. Sometimes for an hour, sometimes for hours on end with out tripping.

As this problem has only just started since I fitted these I thought it must be them, however even if I leave them unplugged I still have an intermittent tripping problem.

Thats why I think the above might be a bit of a red herrng just confusing the whole issue as the other scenario (where Ive got these pond plugs unplugged) that I think is the real reason is one of the isolation switches (washing machine) in the kitchen, whenever I switch this on it trips the switch BUT if I leave the isoloation switch on (after the RCBs tripped) and then reset the RCB the isolation switch is ok and will work (although it still trips intermittently).

However if I switch it off then back on again it trips immediately.

Im thinking that its either a faulty isolation switch or a problem with its wiring but Im not an electrician and certainly dont want to start opening things up that I dont understand so Im hoping someone on here can give me a few ideas as to what actually is wrong and is it something simple that can be sorted before I call an electrician in?

Cheers
Mick

 

[malcolmsanford]

is it this or this

 

[MickM9]

Ah, sorry, I think I might have got my terminology wrong, what I meant by the isolation switch was this



The RCB looks like this

;

 

[malcolmsanford]

Ok well the picture above is the isolator spur, there is normally a fuse in the left side of that, the same as you get in a plug, I assume that is ok

The bottom picture is of the two things I posted lol ...........ok the left one saying 30mA is your RCD the 2 on the right saying B40 and B32 is your MCB Which is tripping I would imagine the left one?

 

[MickM9]

Hi, neither the B40 or the B32 is tripping (nor any of the others on the board), when the problem occurs its the middle grey switch that trips ? I found it strange that no others went off, is that normal ?

 

[MickM9]

BTW, yes, the fuse is ok in the isolator spur.

 

[telectrix]

assuming its the RCD ( the one with the test button) then you have an earth leakage problem. this could relate to more than 1 appliance. what you might have is cumulative leakage where more than one item has leakage, each individually insufficient to trip, but added together . bump. tracing the problem requires test gear or hours of trial and error. suggest a competent sparks could solve in a hour or 2.

 

[malcolmsanford]

Yes that is what that switch is therefore .............it is your RCD

Residual-current device - Wikipedia, the free encyclopedia If this is of interest it will explain what it is and what it does in your installation.

I would bet that as this is due to dampness some how getting into the new installation.

The first scenario can just be what is called inductive load. When you just reset the breaker with the pumps plugged in, the 3 pumps will try and start at once and will often as not unbalance the RCD and cause it to trip. Best to do what you do now. Unplug them and reset, then put on on at a time.

The main problem though I think is your have dampness getting into the installation somewhere and that is causing the RCD to trip. You could check this if you had what is called an Insulation Resistance meter, this would check if your installation is sound, it is like a pressure test on a water supply.

For now as the weather is nice I would look over the entire outside system and see if you can spot any dampness or moisture in a join or the plugs.

 

[MickM9]

OK, excuse my ignorance but can you explain roughly what earth leakage is and how it happens? I dont mind doing the trial and error if I know what Im looking for.

 

[MickM9]

Hi Malcolmsnford, ok I get the dampness on the external system but even when theyre disconnected the isolator switch on the internal system still trips?

 

[telectrix]

earth leakage is where either the "live" or the neutral leaks current to earth. this will cause an inbalance of current in the RCD causing it to trip. the current required is 30mA ( 0.03A) and this value can be exceeded as malcolm says, by damp in a fitting causing leakage to earth.

 

[malcolmsanford]

When you say unplugged your physically removing the pumps from 3 plugs? but the cable from the isolator to the 3 plugs I assume is still there and is switch on ............

If that is the case then the RCD will still trip if there is no load ie the pumps plugged in, if there is dampness getting into the system.

 

[MickM9]

When you say unplugged your physically removing the pumps from 3 plugs? but the cable from the isolator to the 3 plugs I assume is still there and is switch on ............

If that is the case then the RCD will still trip if there is no load ie the pumps plugged in, if there is dampness getting into the system.

Yes Im physicaly removing the plugs from the pump. The plugs were being used on an extension lead which was ran from a different part of the house than the kitchen so was totally seperate from the isolator which is why I didnt think the two issues were related.

So the set up is now is I have no cables running out into the pond area but the tripping still happens on the isolator switch, so it would appear that is where the main problem is.

So am I right in assuming that from telectrix's diagnosis it seems that the earth leakage may be occurring at the isolator switch, or at some point in its circuit?

Not that I can do anything about it myself but it would be nice to be able to give the electrician a bit of a heads up when he comes and maybe save him some time.

 

[malcolmsanford]

What is the isolator switch feeding?

 

[telectrix]

it would be a good idea to fit a double pole isolator in the house to feed the outside equipment. then , by turning that off and seeing if the tripping was cured, you would then have narrowed it down to the outside.