rcd probs

[lee mcgregor]

recently went to a client house to investigate a trip main switch rcd. on getting the the client had already reset and everything was working just fine , 4 week later and go another call saying this time it had tripped through the night whilst everyone was sleeping . now ive tested rcd on both 1/2 ,1 x5 and all coming back as should .now being through the night nothing really was on or in use except maybe alarm clocks and the extensions being left on , smoke alarms and maybe things on standby. . any suggestions ,have pat tested appliances to . rcd,s can e a pain in the butt sometimes . also would be alot easier to find if something was causing a prob all the time , but does not seem to be the case . thanks

 

[kablue2000]

fridge/freezer washing machine???

 

[padmore12345]

went to similar job once turned out it was a pipe in the airing cupboard on the three way valve with a tiny drip of water entering it. really hard to notice it cause when the pipe was hot it dryed drip out so wasnt until the pipe cooled down in the middle of the night that it got wet inside and tripped out the house. so investigating the heating may be fruitful.

good luck

 

[sparkswillfly]

have you done ramp test it may be more than 1 apliance with say a 12 ma leakage and the rcd letting go 21 ma

 

[Des 56]

Intermittent tripping rcds are our nemesis


Some thoughts
The RCD tests out of the way, other than those, have you ramp tested the RCD?
Clamp meter on the earth to see whats leaking maybe perhaps assisting it to go out
Fridge or freezer perhaps,stat clicking in, compressor tipping it over its threshold
Rig up a socket independant of the RCd and let the householder use and monitor main culprit appliances off this socket


I can sympathise with the problem if not being much help,its so much easier to have worse fault that stays in the system and can be found than these nightmares

 

[MySpark]

Doesnt have to be a faulty appliance, damaged wires getting damp for instance, as an area cools down at night, condensation will form on wires under floors, a gnawed wire is a perfect situation for faults like this, and remember neutral earth faults will trip an rcd, IR test the circuits at 230 volt will usually bring up these faults . night tripping is nearly always moisture related.

 

[lee mcgregor]

lads thanks for all the help much appreciate yes rcd has been ramp tested and everything is fine . very frustrating but will be trying eveyones advice.

 

[Spudnik]

Outside lights?

 

[Christech]

What manufacturers RCD is it, and how old ?.Only saying because of EMC immunity.

 

[lee mcgregor]

hager , its quite a new house maybe four to five years ........

 

[Christech]

Ring their Tech Support and ask when they started EMC testing their RCD's.
Even though your customer has a newish install of 5 yrs you can't be certain what is there, then and only then give product code of the RCD as they should have changed to denote EMC immunity .

 

[Yooj]

You need to use a suitably accurate clamp meter with mA resolution around the live and neutral of the RCD and not the earth...It needs to be the L&N as the meter will read the discrepancy between these, and this is your leakage to earth, wherever the leakage is, i.e. CPC, Bonding etc.

You then need to switch each appliance on one at a time, and see what leakage you get....Do they have any security lights outside as these could contribute...Though I think the Fridge-Freezer is a good bet.

Here is an example of a suitable meter: Robin K2413F - Clamp Meters Instrument Hire, Instrument Sale, Instrument Calibration UK

Yooj