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Need some help re. electrics/boiler

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MrPT
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Need some help re. electrics/boiler

Post by MrPT » Mon Nov 27, 2017 4:57 pm

I'm after some advice re. what to do next with our problematic electrics and/or boiler. A bit shameless, but I would really appreciate any pointers as I'm trying to not rack up bills bouncing from one trade to another.

My wife and I live in the ground floor flat of a victorian house in London. It was converted into two flats about ten years ago and since then we've found the odd quirk in the electrics and plumbing, but nothing major. Last Wednesday at about 11pm, while we were watching TV, an RCD in our consumer unit tripped. This RCD supplies the flat's three mains circuits, each with their own MCB - two 32A socket loops, the first of which includes the boiler, and one dedicated 40A cooker circuit. I could reset the RCD, but only after manually tripping the first MCB. This left us with one mains circuit, on which we are now surviving with the help of a few extra multi-ways and layers of clothing. :cry:

Upon inspection, the boiler had a small puddle underneath it. Maybe two tablespoons of water. Me, putting 2 + 2 together and possibly getting 5, what with the cold snap and our heating turning off about an hour before the RCD tripped, thought that the boiler had developed a fault due to condensation or a temperature-related leak. Drying out the boiler for a few hours using a portable heater seemed to allow us to reset the boiler MCB and the RCD, but I have no way of proving this. Whether the drying helped or not, what I have been able to do every day since then is deliberately trip the boiler MCB just before bedtime and re-enable it in the morning so that the heating is on when we get home from work. This stops the RCD being tripped while we are asleep or out and killing the fridge etc, and the boiler has run every day for 4-5 hours with no issues while I've been doing this. We've also disconnected every mains plug in the house, and I've also disconnected a short, double socket spur that was added a couple of years ago (the last time the electrics were altered). No effect on the RCD/MCB behaviour.

Make sense, so far? Still awake?

So... local boiler engineer comes out and immediately points out that the switch fuse should be 3A instead of 13A and the ground connection on the PCB isn't in place. Great, I think, but sorting those two things makes no difference. All basic meter checks are fine and the place where the water was dripping from is on the other side of the boiler to its PCB, which is bone dry. He notes that the MCB remains tripped even if the boiler fuse is removed, but I had already tested this myself and know that the fuse doesn't fully isolate the boiler from the mains circuitry. But he then rigged up a short mains lead and ran the boiler off a working socket on the other MCB for about 20 minutes in total, covering heating and hot water. No problem! :?

I agree with the verdict that we need to answer the electrical question before he can service the boiler confidently (he was actually really good to deal with), but it still nags me that the leak and the power cuts started happening at the same time. Am I missing anything? Apart from the unlikely rat-chewed-wire theory, the only common factor I can see is the cold weather, which might be causing some interstitial damp somewhere on that mains loop and also, by coincidence, a bad expansion leak (or similar) with the boiler. There are also the grounding points on the the copper pipework to consider, but I would have thought that these would be isolated from the boiler PCB.

Any ideas? Quite prepared to pay for an electrician, I just know that this forum has some serious brainpower! Thanks for reading. :)
2008 Z4MC: heavy wheels | crap suspension | skittish rear end | wobbly engine | not enough induction noise | underwhelming turn in | inconsistent braking | lardy battery | chubby steering wheel
2006 Z4 2.5si: gone

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Need some help re. electrics/boiler

Post by Smartbear » Mon Nov 27, 2017 5:04 pm

Hi, has your system got a separate hot water tank? Our place has this & the electric immersion heater developed a fault which kept tripping the electrics.
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Need some help re. electrics/boiler

Post by MrPT » Mon Nov 27, 2017 5:08 pm

Smartbear wrote: Mon Nov 27, 2017 5:04 pm Hi, has your system got a separate hot water tank? Our place has this & the electric immersion heater developed a fault which kept tripping the electrics.
Rob
Ah, good point. Forgot to mention that it's a combi - a Worcester 28i Junior.

A tank and immersion heater would actually be handy right now!
2008 Z4MC: heavy wheels | crap suspension | skittish rear end | wobbly engine | not enough induction noise | underwhelming turn in | inconsistent braking | lardy battery | chubby steering wheel
2006 Z4 2.5si: gone

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Need some help re. electrics/boiler

Post by Smartbear » Mon Nov 27, 2017 5:13 pm

So you know the boiler works without tripping out if it’s powered by an alternate circuit- this proves the boiler is ok.
What you have cut out is the original boiler wiring, I would try making isolations to the circuit and see when it stops tripping?
Have you got access to a megger to test the circuit integrity?
Rob
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e89 Sdrive 30i, this ones busted, pass me another...
e85 3.0si sold

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Need some help re. electrics/boiler

Post by MrPT » Mon Nov 27, 2017 5:30 pm

Smartbear wrote: Mon Nov 27, 2017 5:13 pm So you know the boiler works without tripping out if it’s powered by an alternate circuit- this proves the boiler is ok.
What you have cut out is the original boiler wiring, I would try making isolations to the circuit and see when it stops tripping?
Have you got access to a megger to test the circuit integrity?
Rob
I don't mate, just a hobby multimeter.

There's nothing on the circuit with the MCB that's tripping now, unless there's a plug socket somewhere in this 45sqm shoebox that we haven't found in 3 years. The only thing "plugged in" is the boiler, and that's because it has a fused switch and not a dedicated un-switched socket (like the white goods in the flat - again, that would have been handy right now!).

Any other simple checks I can do without blowing my head off? Switch the MCBs over, maybe? I could also remove and visually check all the socket wiring on the trippy MCB.
Last edited by MrPT on Mon Nov 27, 2017 5:46 pm, edited 1 time in total.
2008 Z4MC: heavy wheels | crap suspension | skittish rear end | wobbly engine | not enough induction noise | underwhelming turn in | inconsistent braking | lardy battery | chubby steering wheel
2006 Z4 2.5si: gone

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Need some help re. electrics/boiler

Post by Smartbear » Mon Nov 27, 2017 5:45 pm

You could try swapping the mcb over (after killing the live side of course) it doesn’t sound like an appliance at fault but more likely a circuit wiring problem.
Hopefully a proper electrician will be along later, I just play with the electrics on the railway :?
Rob
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e89 Sdrive 30i, this ones busted, pass me another...
e85 3.0si sold

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Need some help re. electrics/boiler

Post by MrPT » Mon Nov 27, 2017 5:48 pm

Smartbear wrote: Mon Nov 27, 2017 5:45 pm You could try swapping the mcb over (after killing the live side of course) it doesn’t sound like an appliance at fault but more likely a circuit wiring problem.
Hopefully a proper electrician will be along later, I just play with the electrics on the railway :?
Rob
Haha, well thanks for your help anyway, Rob. Good to keep the ideas coming.
2008 Z4MC: heavy wheels | crap suspension | skittish rear end | wobbly engine | not enough induction noise | underwhelming turn in | inconsistent braking | lardy battery | chubby steering wheel
2006 Z4 2.5si: gone

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Need some help re. electrics/boiler

Post by TonyP » Mon Nov 27, 2017 6:09 pm

I had a persistent fault with the RCD in my place that would randomly trip out, my sparky cousin tested the RCD & it had gone weak & was tripping far too easily, he advised replacing the 3 ring circuits with RCBO's (individual RCD's effectively), problem sorted :thumbsup:

As per your own suggestion backed up by smartbear you have nothing to lose by swapping the MCB's over to prove if the fault follows it or stays with the cabling, **disclaimer - make sure everything is isolated first!!!**

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Need some help re. electrics/boiler

Post by Silverzedtom » Mon Nov 27, 2017 7:31 pm

First thing I’d be doing if it hasn’t been done is plugging a socket tester in. Very basic, and not at all guaranteed to find your problem - but it might give you a better idea of any obvious faults. Less than a tenner in screwfix
30C55F66-2468-4603-AFA0-5D1DABFB7F33.jpeg
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Need some help re. electrics/boiler

Post by MrPT » Mon Nov 27, 2017 9:04 pm

Silverzedtom wrote: Mon Nov 27, 2017 7:31 pm First thing I’d be doing if it hasn’t been done is plugging a socket tester in. Very basic, and not at all guaranteed to find your problem - but it might give you a better idea of any obvious faults. Less than a tenner in screwfix 30C55F66-2468-4603-AFA0-5D1DABFB7F33.jpeg
Was looking at these - good shout. Certainly more appealing than dismantling every socket. Ok so I'll probably try that and the MCB swop next.

I just got back from work and flicked the MCB back on. It has been off for about 6 hours. Heating is on, flat is warming up and I'm sure it will be fine for 2-3 hours now before the pre-bedtime visit to the consumer unit to say goodnight. :roll:
2008 Z4MC: heavy wheels | crap suspension | skittish rear end | wobbly engine | not enough induction noise | underwhelming turn in | inconsistent braking | lardy battery | chubby steering wheel
2006 Z4 2.5si: gone

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Need some help re. electrics/boiler

Post by raymond.harper » Mon Nov 27, 2017 9:29 pm

We rent out a flat and got a call from the tenant saying water was coming down the boiler. Turns out there was heavy rainfall and due to the direction of the rain it went down the flue into the boiler

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Need some help re. electrics/boiler

Post by srhutch » Mon Nov 27, 2017 10:35 pm

raymond.harper wrote: Mon Nov 27, 2017 9:29 pm We rent out a flat and got a call from the tenant saying water was coming down the boiler. Turns out there was heavy rainfall and due to the direction of the rain it went down the flue into the boiler
I had this also. Been in the house 12 without issue, but one day due to excess rain/direction is entered the flue. Blew the circuit board though.
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Need some help re. electrics/boiler

Post by MrPT » Mon Nov 27, 2017 11:01 pm

srhutch wrote: Mon Nov 27, 2017 10:35 pm
raymond.harper wrote: Mon Nov 27, 2017 9:29 pm We rent out a flat and got a call from the tenant saying water was coming down the boiler. Turns out there was heavy rainfall and due to the direction of the rain it went down the flue into the boiler
I had this also. Been in the house 12 without issue, but one day due to excess rain/direction is entered the flue. Blew the circuit board though.
Amazing how common it is when you consider how expensive boilers are. My dad had it with a brand new install and a botched flu angle. Just a small piece of corrugated plastic sorted it forever.
2008 Z4MC: heavy wheels | crap suspension | skittish rear end | wobbly engine | not enough induction noise | underwhelming turn in | inconsistent braking | lardy battery | chubby steering wheel
2006 Z4 2.5si: gone

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Need some help re. electrics/boiler

Post by Silverzedtom » Mon Nov 27, 2017 11:32 pm

Off topic but here is a boiler I got called out to last week. Had to replace the fan, ignitor and leads due to water ingress. Glow worms are particularly bad for sucking in water, I have been called out to loads.
Fitted in 2008 by BG
9F4F0F47-8128-466F-B68B-5986926EA64C.jpeg
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Need some help re. electrics/boiler

Post by MrPT » Mon Nov 27, 2017 11:37 pm

Silverzedtom wrote: Mon Nov 27, 2017 11:32 pm Off topic but here is a boiler I got called out to last week. Had to replace the fan, ignitor and leads due to water ingress. Glow worms are particularly bad for sucking in water, I have been called out to loads.
Fitted in 2008 by BG
I wonder if it was the same guy who designed these and the Z4 roof motor? Relocating the motor is a bit easier though. :D
2008 Z4MC: heavy wheels | crap suspension | skittish rear end | wobbly engine | not enough induction noise | underwhelming turn in | inconsistent braking | lardy battery | chubby steering wheel
2006 Z4 2.5si: gone

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