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RCD and power cuts

There's a fault on the underground cable 'somewhere', Northern Grid can't find it, and so we're getting a ridiculous number of power cuts.

The 'reset the clocks' routine is well rehearsed and I can't see a way round having to go through it. However, we've got a pond pump/filter and heater on an indoor RCD which is plugged into a 13A socket and which trips out every time.

Is there an alternative that will protect the pump/filter and heater and which will also reset if it detects there's no continuing fault?

The reason I ask is that we've been away for several weeks during freezing weather, the power has gone off, the RCD has tripped and the pond has frozen over and the fish have died.

I realise that it's probably completely against the idea of having an RCD but perhaps there's some device for circumstances like these?

Reply to
F
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Sounds like you have a fail-safe RCD - i.e. trips off when power fails. You can get ones which don't do this - of the plug-in type, it seems to be a roughly 50/50 split between the two types.

Reply to
Andrew Gabriel

Your RCD is an active type. These need to be manually reset after a powercut.

You need to swap it for a passive RCD - a passive RCD will restore power to the pond when power is restored to the house.

Does the socket that the pond heater is plugged into not have RCD protection at the CU?

Reply to
ARW

Normally called a neighbour with a key I think.

Brian

Reply to
Brian Gaff

You may well laugh at this, but has the company approached any deviners? I understand they can often find faulty cables as well as water leaks. These people have tuned their nervous systems to be sensitive to change s in electrostatic forces so can detect things like this.

Brian

Reply to
Brian Gaff

It's one of Aldi's kits.

I'll look at finding one then.

Yes. The CU was (is?) a traditional Volex fuse board and I've replaced the wired fuses with RCDs. When we get a power cut the only RCD that trips is the one that is plugged into an indoor 13A socket and which feeds the outdoor sockets into which the pond electrics are plugged.

Reply to
F

Then there is already RCD protection for the pond..............................

The answer is simple - remove the offending RCD - you do not need two RCDs in series.

Reply to
ARW

They've dug up the pavement and found nothing other than that, in wet and cold weather, large holes fill with water which then freezes.

They've drilled a whole series of 5mm holes above the cable run to check for gases that are produced when a cable is shorting but have found nothing.

They've fitted a 'badoing' (sp?) at the substation to restore power automajically when the first of its two fuses blows.

They've moved the 'badoing' further away to try to get the cable to burn out!

And, yesterday, they dug another hole just along the street and have announced that they found a bad joint to a neighbour's house and the problem is fixed. Tadaa!

After multiple disconnections over several years, totalling over 20 hours since last September, with four in the last two days, we'll see.

Reply to
F

Aah! Thanks!

I was under the impression that an outdoor socket had to have its own RCD if it was plugged into a socket within the house. Hence one for the pond and another, at the other side of the house, for the electric strimmer and hedge trimmer.

As an aside, why does the pond RCD trip when we have an outage but the ones on the CU stay on?

Reply to
F

The plug type RCDs are (usually) an active RCD ie they need a manual reset after a powercut. Handy for outdoor power tools where you may not want the tool to automatically restart when the power is restored - but no use for fishponds or fridge freezers where you want the power to be restored (that's when you use a passive RCD).

Reply to
ARW

I'm wondering whether that should be read as "and I've replaced the wired fuses with MCBs"...

... or perhaps not.

Reply to
Andy Wade

Are you sure? I don't think that's possible. Did you replace the rewireable fuses with MCBs, perhaps?

Alex

Reply to
Alexander Lamaison

There was atype of cable used through the 70s and 80s that was prone to manufacturing QC problems, notorious for developing faults, and required very precise and exacting jointing requirements. Looks like you may have had some!

Reply to
Broadland Wanderer

It should be, yes.

Does the presence of MCBs in the CU mean that there's no protection for the outside sockets if I remove the RCD they're fed from?

Reply to
F

Yes, my mistake.

Reply to
F

Unless you have some other RCD installed in the circuit (seems unlikely), there would not be the necessary protection to use electricity safely outdoors. You will need to keep using one in the plug.

Of course, the MCBs offer other sorts of protection - the same sort as a fuse - but I don't think that's what you're asking.

Alex

Reply to
Alexander Lamaison

Thanks, that's what I needed to know.

Reply to
F

YES.

And well done Andy Wade for spotting that one.

Reply to
ARW

and no use after a time switch feeding Christmas lights that someone put in a local chapel. I know he's safety obsessed but .....

Reply to
charles

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