Immersion - RCD or non-RCD?

[Goonerak]

Should my immersion heater be RCD protected?

[Dave Jones]

No

[Dave Fawthrop]

| Should my immersion heater be RCD protected?

Probably a bad idea. RCDs are to stop the electricity killing *people* the chances of anyone touching an immersion heater supply are slim indeed.

The chances of a 30milliAmp leakage in immersion heater itself and causing nuisance trips are high.

Not that I would take one out if already fitted.

[Goonerak]

Thank you.

[Lurch]

On Sun, 25 Sep 2005 12:23:52 GMT, "Goonerak" scrawled:

Depends.

[tony sayer]

In article , Dave Fawthrop writes

Muggins here once put his mitt round the back of a HW tank once to find out the hard way that the cover had been left off!. Hand bounced back and forth a few times with the current repelling it and the wall knocking it back on;!.

Yes, if you want an early warning when the heather elements are corroding. No if you can't have any trips.

I've just been informed by the one protecting the office/workshop that a fluorescent light is on its way out with excess live -> earth leakage.

As to your original question we've got the whole house on a 30 ma one and no problems, except that some accidental live contacts have happened!.....

[John Rumm]

Nope... no need for it, and it is more likely to cause nuisance trips.

[Lurch]

On Sun, 25 Sep 2005 14:32:55 +0100, John Rumm scrawled:

Incorrect, it depends.

[Lobster]

on...?

[dennis]

True.

I would love to know how a non-faulty immersion heater can trip an RCD.

If it does then its probably time to replace the heater or the trip as one is duff.

[Lurch]

On Sun, 25 Sep 2005 16:06:16 GMT, Lobster scrawled:

Circumstances.

I'm probably being pedantic but dpending on earthing arrangements and locations it may require an RCD.

If it doesn't _need_ one then I agree, put it on a non-RCD circuit.

[meow2222]

Earth leakage. Theyre famous for it. They'll continue working happily for a long long time while being a bit leaky, and the leakage in the circumstance doesnt cause any safety problem.

Even heavy leakage is ok when youre not on a TT setup. Had one that ran like that for a long time. Most of the element had long gone, the water took its place.

not at all. If it works fine and its no danger, there's no problem.

Its counterintuitive for folk that were brought up believing water and electricity dont mix, but of course that was never an accurate belief. Commercial electrode heaters are still being installed new, and have proven quite safe, despite common assumptions.

NT

[Lurch]

On 25 Sep 2005 11:57:12 -0700, [e-mail] scrawled:

But nonetheless, still faulty though, technically.

[Andrew Gabriel]

The insulation is Magnesium Oxide, which is hygroscopic absorbs water). After a few moment's operation, the moisture will have been driven away from the element and it will not leak, but if you can't turn it on in the first place because it trips an RCD, then you can't get it working.

When PAT testing such appliances, they are allowed to leak initially before they get warmed up, and you then take the real measurement.

Secondly, a leaking immersion heater doesn't represent a significant safety risk.

Many immersion heaters get used once in 10 years when the boiler packs up. To have an RCD stop it working at that point for no good reason would not be a good thing.

[Owain]

Not faulty. Just operating outside specified parameters :-)

Owain

[John Rumm]

If you are on a TT install then *all* circuits should be RCD protected.

However in these cases it is usual to have more than one RCD, with a whole installation one (usually 100mA trip, with a time delay) and then a downstream one for the things that one would normally RCD protect on other types of earthing arrangement (socket circuits likely to be used for portable appliacnes outside etc). Often accomplished by replacing the incomer switch on a split load CU with the the time delay RCD.