EP2000 Programmer tripping RCD

Jimbo · Oct 1, 2012

Hello,

I have a Potterton Neateheat 10/16 with an EP2000 programmer, which has been been working fine and very faithful for the past 26 years.

I recently had the consumer unit changed from the old fuse wire to a Wylex High Integrity unit. When the fused spur is switched on for the boiler
the RCD which protects the MCB for the upstairs ring (of which the CH fused spur is connected) trips.

Fault finding so far,
Purchased a new EP2002 programmer, same back plate, (although I have fitted the new one), still trips.
To eliminate the component parts of the system, ie pump, 3 way valve, stat & boiler I removed the front panel of programmer and linked
Live - HW boiler starts no trip, then linked Live - CH boiler starts no trip.

I then disconnected the feed to the fused spur and ran a seperate cable to it from the unprotected side of the main 100a trip, (yes I know, dodgy
but I had switched of all RCBO's & RCD to the rest of the house, only this cable was live as I wanted to simulate my old unprotected fuse box),
refitted the front of the programmer and the programmer works, led's light CH & HW work fine.

Contacted Potterton support ..... "Hmmmm never heard of that mate, can't help you!"

Any ideas please, Jimbo

ferg · Oct 1, 2012

Hi and welcome to the forum.

From the wording in your post it looks like you may be the homeowner and not the qualified electrician who fitted the new board.
I would recommend getting a qualified electrician to look at it as some basic testing would identify the problem.
They would do this without connecting faulty wiring direct to the main switch without any protection to speak of.

I hope you have a thick skin as this forum is populated, mostly, by qualified sparks who quite rightly get upset about folks carrying out potentially dangerous DIY electrical work.

Ferg

HandySparks · Oct 1, 2012

Welcome to the forum.

I think it's unlikely to be the programmer. From memory that programmer doesn't use an earth connection (double insulated), and so it's unlikely to produce the earth fault which is the usual cause of an RCD tripping. You'd be better off getting someone in who can do some insulation resistance testing rather than changing components in an effort to isolate the fault.

sedgy34 · Oct 1, 2012

your heating cables and equipment need testing theres earth leakage somewhere

Jimbo · Oct 2, 2012

sedgy34 said:
your heating cables and equipment need testing theres earth leakage somewhere

Hi All,

Thanks for the advice, much appreciated.

Checked that all relevant RCD's MCB's & RCBO's had there relevant Neutrals going to the correct bus bar, all good.
Although as you say Handysparks, the programmer is double insulated mine has a connected earth (at the fused spur)
running to the back plate.
Disconnected all wires then ran an insulation test on the cable from the feed side of fused spur to the programmer,
all seemed ok. Joined all the wires together at one end, then ran same test on each wire but to a good known earth, a
and the live to earth showed a fault.
Ran a temp new cable from fused spur to programmer all ok and those magic sounds from the boiler were heard,
'Tick Tick boom !

I can only presume that somewhere under the floor the insulation on the live is crushed somewhere, which wasn't enough
to short on the old fuse board but a sensitive RCD picked it up.

Thanks again
Jimbo