Shower Trips breaker

[AnthonyL]

It seems to be happening more frequently and usually at the point my wife is about to rinse her hair but I don't have the problem but the MCB trips. If I hear her squeal I reset it.

The shower circuit was installed around 30yrs ago and the shower unit itself replaced about 10yrs (or maybe more) ago with a Triton Ivory III. Where do they hide the power rating?

In any event the MCB is 45amp which should cover all the Ivory III range.

Do MCBs become more sensitive with age? Or should I be worrying about something else?

[Tricky Dicky]

I cannot find any info on your shower but I would guess if this was a repla cement for a 30 yr. old shower chances are the previous shower was a lot le ss powerful and the wiring installed probably adequate then may not be suit able now. as for the reason why it does not trip when you are in the shower but only when your partner it might be because she spends longer in the sh ower the result being more warming of the wiring causing the MCB to trip.

Richard

[DerbyBorn]

Tricky Dicky wrote in news: [e-mail]:

Or steamy atmosphere.

[AnthonyL]

Funny - I've just downloaded the full manual from the Triton site which is how I know the MCB matches the shower range.

[AnthonyL]

Go on. How does that work? I suspect I'm the more likely to have a window open.

[Tricky Dicky]

I put in Ivory 3 in my search instead of Roman numerals hence zilch result. So it looks like yours is one of the high power versions there will probab ly be a label inside the cover to confirm which. As well as the wiring, che ck all connections are tight loose arcing wires will trip MCBs for fun.

Richard

[charles]

Is this just an MCB? It isn't an RCBO by any chance?

[Ash Burton]

Check your connections at the shower and the mcb end for tightness/signs of overheating.

Does your wife shower at the same power setting as you?

A 10.5 kW shower on full power could draw over 45A at 230 volts.

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[newshound]

I have heard of MCBs becoming more sensitive although I havn't had this problem myself. IME when electric water heaters start tripping it is usually because the element is beginning to fail. It could also be a small water leak into the wiring side.

[ARW]

Most unlikely as the 10.5kW shower will be the shower raing at 240V.

It does mean that the OP could well be drawing close to 45A if his incoming supply is 250V.

MCBs can become more sensitive and if the MCB is crammed into a CU with no breathing space at either side of it and is now sensitive you might have your answer.

[Vir Campestris]

My son's shower started doing this. Rather than mess with an intermittent fault 3 hours drive away we called the manufacturer. Their service guy changed the element. Problem fixed.

Andy

[Graham.]

Was his also tripping the MCB or was it an RCD/RCBO tripping due to earth leakage which is more likley IMHO

[Vir Campestris]

My mistake. It was earth leakage.

Andy

[AnthonyL]

I've put some pictures of the equipment at:

I'm trying to work out what the mains cable rating is, what the MCB is (the button says 30amp).

The shower unit has 7.8Kw to 8.5Kw which presumably is what it sucks at 230v and 240v?

Is the MCB right on its limit and what is the highest rating I can put in?

[Andy Burns]

The MCB is *above* its limit, whatever voltage you're getting.

Silly question, does your missus take longer showers than you, or at different times of day to you when voltages may be different?

[ARW]

The MCB is overloaded. You are drawing more than 30A.

MCBs do not instantly trip when their rating is passed. eg they will run at

1.45 times their rating for half an hour before tripping

is the answer.

[Andy Burns]

Strange the sticker says 45A, the red "on" button does correspond to

30A though, 45A would be green button.

Unless the O/P wants to retain the "vintage" feel of his CU :-P

seriously, go with the new one ...

[AnthonyL]

We tend to take showers in the morning as our E7 works till about

11.45. Yes wife takes longer and normally after me, though the cut-out can happen even if I haven't showered. We don't live far from a power station (with a few miles). I guess at this time of year voltages tend to be good.

I changed the shower unit myself about 8yrs ago. That unit was professionally installed and the mains cable put in.

Looking at the figures I wonder if that was a 7.5Kw unit that I took out.

Am I right that the cable, 7 strands at 1.1mm which is not chased into the wall has a capacity of 46amps. The CU is high in one corner of the kitchen (say 4m x 4m) and the shower is upstairs above the other corner, so ~8m run?

The house was rewired in around 1986. Has someone skimped on the CU?

[AnthonyL]

Many thanks. Surely though I'm only drawing 35amp? My cabling seems to be 6mm2 so should be good for 40amp so the above MCB should be safe?

[Andy Burns]

Diameter presumably? if so, sounds like 6mm^2 cable

yes

You /could/ even get away with 4mm^2 for 8.5kW, clipped direct, at that distance, so cable is OK.