shower tripping rcbo?

[whazza2]

Replaced an mcb with an rcbo for a shower as the client wanted the extra protection without replacing consumer unit.

It's a 40A rcbo in 6mm for an 8.5kw shower. Approx 15m run from garage to shower.

As soon as the shower is turned on it trips the rcbo

Any ideas?

I didn't have any testers to test cable, possibly poor insulation.

 

[monkey5]

water heater/element had it.

wayne

 

[Zeespark]

Poor IR would be My best guess.

AndyGuinness

 

[choccy]

Think you need to get a tester and do some checks.

L+N to earth to see if the insulation resistance is ok.

Could be that the shower have got water within it and causing you a problem?

Why did you change the mcb to an rcbo? did you do work?

 

[Revved Up Sparky]

I would start by doing a 500V IR test between L-E, N-E so that the cable can be eliminated. It sounds like a possible N-E fault.

If the cable is clear and RCBO not faulty then that leaves the shower unit. Perhaps one of the elements is shot ?....

I look forward to hearing how the fault finding goes !

 

[PC Electrics]

So you went to a job to add an RCD into the circuit without the means of testing that circuit to find out if it contained any RCD tripping faults?

Hhhmmm!!!

Element shot or broken insulation in the isolator would be my most likely guesses.

 

[Andy™]

I didn't have any testers to test cable, possibly poor insulation.

er....

your going to be working as an on-call spark for a hospital, yet you dont have any test equipment?

dare i ask what the trip times were, or did you just press the test button and think 'thats quick enough'

 

[Bez]

Would also have used a 32A.

40A sailing a bit close to the wind for me with 6mm

 

[Andy™]

Could be that the shower have got water within it and causing you a problem?

as its a shower, i would hope that it works when there is water inside it....

 

[whazza2]

[quote name='Andy

 

[Bez]

Does it trip on switching the pullcord, or when the shower is turned on?

Did you check connections?

 

[sparkytim]

Would also have used a 32A.40A sailing a bit close to the wind for me with 6mm

Hi

As the shower is a fixed Load then it is exempt from the need for overload protection. If the cable meets the requirements for the fixed load then no problem with a 40 Amp RCBO.

See BRB under Overcurrent - exemptions for requirements of Overload protection

 

[whazza2]

It doesn't trip with isolator switched on, only when start button pressed. Is it not best to have shower rcd protected? He wants it for his own satisfaction

 

[Bez]

Hi As the shower is a fixed Load then it is exempt from the need for overload protection. If the cable meets the requirements for the fixed load then no problem with a 40 Amp RCBO.

See BRB under Overcurrent - exemptions for requirements of Overload protection

Hi,

Didn't say there was a problem, just the fact that a 40A Type B RCBO will happily carry 50A all day without tripping, and 6mm cable is rated at 47A at the very best, makes me err on the side of caution.

A 32A breaker would be more than enough for an 8500w load, just me I guess

---------- AUTO MERGE Post added at 23:00 ---------- Previous post was at 22:57 ----------

It doesn't trip with isolator switched on, only when start button pressed. Is it not best to have shower rcd protected? He wants it for his own satisfaction

Definately, especially with water about, but you need to do some tests first.

R1 + R2, IR, ZS etc.

 

[m4tty]

Think we may have missed the obvious bit I may be wrong

Did you move the neutral to the correct neutral bar in the cu?

Cheers

 

[Megaohm7]

Could be an heating element on the way out in the shower itself, but the circuit does at least need an insulation resistance test on it to prove the insulation is not breaking down. These days with the circuit protection that is newly fitted you really need to be competent to use a meter as it will save you time in fault finding as well.

 

[kme]

But....it ISN`T a "neutral in the neutral bar", is it? It`s an RCBo - so the question is:

Did he move the cct neutral into the RCBo?????

n.b. If you couldn`t test it, you haven`t issued a cert. and you don`t know the CPC is continuous...........

Naughty boy. I don`t care if "you don`t have test gear for personal use" - if that is the case you can`t do "personal works" can you??

If you want to moonlight -buy the necessary equipment :red card

 

[SPECIAL LOCATION]

I am just gob-smacked that when changing the characteristics of a protective device you don't do the basic safety checks to ensure the change you are doing is safe..

And that the "RCD" portion of the "RCBO" is operating to the correct operating times..

Especially as by you own admission.. 'the client' A 'family member' wants the work done for their extra protection..

So to get the extra protection you cut corners and do half a job????

Contradiction or what!!!

In my book this is on a par with changing a car wheel..

but not bothering to check the wheel nuts are tighten back up

or if the tyre is correctly inflated.

BASIC essential checks..

I believe my esteemed colleagues have already covered all of the bases you should have already known to check if you are able to change an MCB for RCBO.

 

[m4tty]

Sorry kme. You know what I meant tho lol. Retiring to pit now

 

[Manator]

I have to say I have thanked quite a few posts on this thread, but one was thanked out of pity.

Do not cut corners! The electrician is the only protection against electric shocks, but he has to perform each task properly.