MEM RCD failure?

[sirocco]

I have a split MEM2000 board (15+ years old) with four circuits each with MCBs protected by a single 100A 30ma RCD.
The RCD has been tripping out over the last 4 days at increasingly more frequent intervals (initially evry 6-8 hrs now it holds for about 30mins)
It trips with the mcbs on the four circuits switched off! Does this automatically infer that the RCD is defective and should be replaced or are there other checks that should be made?
Frustrated! any advice welcome.
Graham

 

[Sintra]

What results did you get on your ramp rest and 1x & 5x tests?

 

[R G]

What about the neutrals , are they still connected, MCBs are only on the live

 

[rich67577]

The price of a new mem rcd it cheaper to by a new board last time I bought one it was about £80

 

[hotfingers]

Disconnect your live conductors on the rcd side including the neutrals.am sure rcd wil stay up. Connect one circuit at a time will probably trip when you connect faulty circuit but it could be other of number of things ie faulty appliance etc try in plugging everything as wel It may help

 

[hotfingers]

That was suppost to say unplug everything

 

[sirocco]

Thanks for all the replies, the cause was an overloaded 6 way extension lead which has now been binned and replaced. What I have learnt is that going forwards the CU will be replaced (probably Wylex) with RCBO's on circuits which need protection.
I have costed out that an 8 way ,fully populated, box works out cheaper than a couple of MEM rcbos, and much easier to source/maintain.
However the ditching of a cheapo ext lead will do for know!.
Cheers
Graham

 

[rich67577]

Well if you have soled the problem why go the the trouble of changing it all rcd very really go wrong usually a appliance fault