9.5kw shower on a 6mm cable - Electricians in here please!

Me and my electrician friend have fitted the cable
ourselves

Is there an element of untruth here? If you friend really is an electrician you should not need to post this question.

Showers-one of the most controversial and debated topics on this forum.

You could get away with a 6mm cable for a 9.5kW shower. Rating of cable reference method 1 47A. Rating of shower 41.3A.

It really would be best to ask the question before you install any cable. We would have advised 10mm2 cable.

UP

 

This is my first post and I'll probably get shot down for it but what the hell.
As I understand it the shower will pull 41.3A, so your fuse/mcb needs to be bigger than 41.3A ie 45A and the cable needs to have a higher rating than the fuse/mcb. Therefore the cable is dependant on the fuse rating.
If your running a fuse/mcb rated higher than 45A your gonna need a bigger cable.

 

absolutely sub. We did tell him. Best drag in a 10mm2

 

So a 6mm should be ok? Also am I correct in saying
that if the shower is set to a medium power setting
rather than a high, the pull on the cable will be
decreased? (to probably that of an 8.5 ish?)

Irrelevant.

 

Unfortunately it only comes in a 9.5kw version. I
have a 6mm cable which supposedly is only good for an
8.5kw at maximum (as long as its below 18 meters in
length).

My cable is only 9 meters in length. Also the shower
has a power selector.



Then find a 8.5KW shower...

 

Concur Extension.....never ever fitted an electric shower but based upon what I have read through a variety of posts in the past..reckon just whip in a 10.0mm and be done with it.....sure as heck saves a lot of potential future problems.

 

Just placed a clamp meter on my 9.5kw shower - max amp reading was 41amps.

This is wired in 6mm with a 32amp breaker used daily for 2 and a half years never tripped once.

Does this answer you question.

 

<u>Difficult really</u>

1......Design.....
2......Reality......

However reality is no excuse for poor circuit design.

 

>Also am I correct in saying
that if the shower is set to a medium power setting
rather than a high, the pull on the cable will be
decreased? (to probably that of an 8.5 ish?)

Nope. It just means that the flow rate is sped up so the water goes past the heater quicker, therefore comes out cooler.

It will pull the same Amps whether on high, low or medium setting. It is the water flow rate that is adjusted.

 

Just placed a clamp meter on my 9.5kw shower - max
amp reading was 41amps.

This is wired in 6mm with a 32amp breaker used daily
for 2 and a half years never tripped once.

Does this answer you question.

MCBs will only trip when they reach 1.45 times thier rated current and this will be after some time, and having a shower dont take that long that will be why it dont trip....If it works with the correct rated MCB then i dont see a problem...another thing, he said he put the cable in trunking so that is ref method 3 wich downrates it again.

 

Also am I correct in saying
[/i]that if the shower is set to a medium power
setting
rather than a high, the pull on the cable will be
decreased? (to probably that of an 8.5 ish?)

Nope. It just means that the flow rate is sped up so
the water goes past the heater quicker, therefore
comes out cooler.

It will pull the same Amps whether on high, low or
medium setting. It is the water flow rate that is
adjusted.


Many showers also have 2 elements and the medium setting will only swith on 1 element, and so draw less amps, after that is wot u described being a water pressure adjuster to fine tune the heat.

 

As long as your breaker is 40amp it will be ok, because your shower will take 41.3amps (roughly 4 amps per kw) at full load and that will only be for about 15mins, the cable is rated at 48amps anyhow.

 

From table 4D2A, ref meth 3, 6.0mm max current carrying cap is 38Amps...
Before you slay me, I know the correct table is 4D5A but theres no column for ref meth 3 (for some reason)

 

Ha ha, Shower question - with 10mm cable.


Should I take over and make this thread at least 7 pages long lads?

 

Don't steal Handy's thunder.