shower circuit

[ccfc]

Hello all

Got my assesment with elecsa next month .changing neighbours consumer unit, shower is rate 7.8kw at 230v = 34a & 8.5kw at 240v =35a 6mm cable from garage to bathroom then buried in wall to shower via isolator. Ok 6mm cable clipped dirct 47a

so 40a mcb but problem is how do i know there is no derating factor i cant see. Put clamp meter on circuit shower up full pulling 34a you would never have on full power as. It would take your skin off so i asked customer what setting they have it and clamped it again 22a max. Question is do i fit 32a mcb to protect cable incase of and derating but then In is not greater or equal to Ib. Would assesor see this as anon compliance or common sense. Customer does no want rewire and cant use other job for assesment.

HELP please

 

[m4tty]

Your worrying over nothing matey. I doubt the assessor will start looking into rating of shower. Your there to do a board change. I'd personally stick it on a 32a but my mate who I work with alot would put it on a 40a. What was it on before ?

If you explain the situation to the assessor and ask for guidance they will help you out no end. They won't try to trip you up or fail you as they want YOUR money.

Elecsa are a good bunch and have always been helpful.

If your still worried ring their technical department and they will advise how they want it done so when assessment comes you can say you spoke to xyz in technical who said to do it this way. Arse covered

Hope it goes good for you and don't worry too much

 

[ccfc]

Cheers m4tty

Thanks for reply . Shower is 30a bs1361. Like i said never b on full power to bloody hot . Normaly would not think twice and put it on 32a mcb but starting to panic lol still got 3 weeks till assesment just needed to get another opion

Cheers

 

[m4tty]

Wait to see what others say too as ive only been registered 2 years. I personally called the technical helpline before hand to make sure they would be happy with what had been done.

 

[Andy™]

the shower circuits doesnt really need protection against overload, but it does need protection against fault current. providing a B40 covers this, then no problem. B32 would also work (look at time/current graphs)

 

[ProDave]

I'm confused about your varying current readings.

Normally a shower is a FIXED KW of heating power, and you adjust the output temperature by varying the water flow (less water flow = hotter water) So as you wind the temperature dial from hottest to coldest, the power consumption is the same.

There is often a second control that does Off, Cold, Warm, Hot. Now that one will give a different power consumption on warm and a higher reading on hot.

But in any case, the circuit needs to be capable of running the maximum power setting for half an hour (women seem to need longer to shower than the 5 minutes it takes me) so a 32A MCB would be no good. Stick to the 40A one.

 

[ccfc]

cheers andy

i total agree with you and with a zs of .41 the mcb will operate well within time required but surley the first thing you learn about designing a circuit is In>or=Ib & In<or=It and as i dont know what It is as i didnt install the cable so dont know what derating factors may apply using a 32a mcb would be a safer option but then we come back to In>or=Ib(approx 35a) would the assesor see this as a non compliance.

cheers

 

[betty swollocks]

A shower that size I would have it on a 32a

Nothing wrong with a 40a

As for the rest don't worry so much no job is ever 100% black and White and ten sparks completing this job will come up with a wide variation of solutions

As for the assessment itself it will be a walk in the park, afterall they only really really want your money!

Good luck

 

[ccfc]

prodave

sorry shower rating label says 7.8kw at 230v and 8.5kw at 240v.

so you wouldnt worry about the cable running through and in who knows what, derating it and getting hotter and hotter on a 40a mcb or rather have the occasional nusiance tripping with a 32a mcb if the max power is ever used.id rather have the breaker go than the cable. yes i dont think the problem will never arise as i said the max setting takes your skin off and when clamping at the settings usually used 22a max, but as you said if somebody does like it hot then they might get a bit hotter if cable doesnt like it.

cheers

 

[Robin Spark]

prodavesorry shower rating label says 7.8kw at 230v and 8.5kw at 240v.

so you wouldnt worry about the cable running through and in who knows what, derating it and getting hotter and hotter on a 40a mcb or rather have the occasional nusiance tripping with a 32a mcb if the max power is ever used.id rather have the breaker go than the cable. yes i dont think the problem will never arise as i said the max setting takes your skin off and when clamping at the settings usually used 22a max, but as you said if somebody does like it hot then they might get a bit hotter if cable doesnt like it.

cheers

I always like it hot in the shower, the Mrs is always moaning at me saying I leave the water really warm. And if Steptoe got Ali in your next door neighbours shower whilst spraying her wet professional electricians t shirt that she had from the ELex show then things are going to get boiling and the breaker will definately trip if its only a 32amp!!!

 

[Evans Electric]

Nothing wrong with a 40A CCfC , I presume there is an RCD int the circuit .

Have you recorded the tests for the shower circuit and measured Ze at the new board?

How did you connect the meter tails , was there an isolator?

 

[ccfc]

Cheers evans

Rcd-yes

All tests ok r1+r2-0.12 zs-0.38 ir all >999 rcd x1/2 >1999 x1 28.8 x5 18.2

Ze-0.21ohms

Isolator fitted by eon

Did i pass the test

 

[jameseye12]

How did you connect the meter tails , was there an isolator?

Did I ever tell you guys the story about my Elecsa Assessment? When the assesor asked me how I had isolated the tails for the board change I had done, I gave him the textbook answer (contact the DNO) and turned round and said "don't be silly, just whip the fuse out, make sure you 'lose' the seal; it's always worked for me". I thought "can't argue with that" and went off to buy a seal kit off ebay

 

[Robin Spark]

Is that because he could see the seal had been cut and knew you were teling porkies?

 

[ProDave]

as i said the max setting takes your skin off and when clamping at the settings usually used 22a max, but as you said if somebody does like it hot then they might get a bit hotter if cable doesnt like it.cheers

I'm still waiting an explanation of how this shower works.

It's normal to leave the "power" setting on max, and adjust the temperature dial (which adjusts the water flow) to get the right temperature. So the circuit must be capable of running the shower at full power continuously. Believe me, if the MCB trips while someone is showering with wet hair full of shampoo it is MORE than just a nuisance.

So in your case I assume you are turning the power switch down to a lower setting. Why? Can you not get the water cold enough on the high setting, even with the temperature dial at "cold"?

Turning the power down will mean you have to turn the temperature dial up, probably close to maximum to get a decent temperature, by which time the water flow will be a dribble.

electric showers are poor at the best of times IMO and you need all the power you can get to achieve a hot enough temperature with a decent water flow.

 

[ccfc]

Dave

I just asked the owner to put shower on setting they usually use it ran for 10min and max on clamp was 22amp

It has been running on a 30a 1361 for approx 2 yrs since bathroom refurb