9.5kw shower.

[podgypaul]

1st post so be gentle with me, i have used the forum search facility but can't find a specific answer to my question, so thought i would post it, i have just moved house and the house elecs were check by an electrician (arranged by the seller), who amongst other things said the shower cable isn't big enough and needs renewing (it's 6.0mm and needs to be 10.0mm) as it's feeding a 9.5kw shower, the seller has been quoted £200 to have it replace, but is reluctant to have it done as he says "it works perfectly and has never tripped out". i have asked some of the sparks at work and came up with conflicting answers, but going off what they asked me i have come up with some information, the cable run is approx 12mtrs in plaster and through the attic, it goes into a 45a pull switch, and comes from a modern split load consumer unit fed via a 40a mcb and 80a 30ma rcd.
My question or rather questions are- is it safe ? will it continue to be safe ? is it working correctly ? will it continue to work correctly ?
Thanks,
In anticipation of your answers.
Paul.

 

[PrenticeBoyofDerry]

6.00mm2 T&E cable can carry a maximum of 47Amps.
9.5kW at 230V equals 41.3A.
You have a protective device of 45A protecting a 47A cable.
45A isolator
There is 30mA RCD protection.
Voltage drop is okay.
Providing the cable during it's route is not in thermally insulated areas or contained within trunking/conduit, then it seem fine.
It would be the maximum sized output possible, so any new shower would have to be no greater than 9.5kW.
So if you ever intend to update a higher rated shower the cable would require updating.

 

[podgypaul]

6.00mm2 T&E cable can carry a maximum of 47Amps.
9.5kW at 230V equals 41.3A.
You have a protective device of 45A protecting a 47A cable.
45A isolator
There is 30mA RCD protection.
Voltage drop is okay.
Providing the cable during it's route is not in thermally insulated areas or contained within trunking/conduit, then it seem fine.
It would be the maximum sized output possible, so any new shower would have to be no greater than 9.5kW.
So if you ever intend to update a higher rated shower the cable would require updating.

The circuit is actually protected by a 40a mcb, how is it working without tripping ?

 

[securespark]

Because the breaker has a degree of leeway.

They can suffer a slight overload for a long time without tripping.

If the overload is very slight, they will never trip.

 

[ricicle]

40A mcb should take 45.2 amps indefinitely and 58 amps for up to an hour.

 

[podgypaul]

Because the breaker has a degree of leeway.

They can suffer a slight overload for a long time without tripping.

If the overload is very slight, they will never trip.

Thanks for your replies guys, so in summary, it's safe and will continue to work ?

 

[EFLImpudence]

Also, 9.5kW / 240V = 39.6A.

Only 8.74kW at 230V = 37.8A

Less when it heats up.
No leeway needed.

 

[PrenticeBoyofDerry]

Thanks for your replies guys, so in summary, it's safe and will continue to work ?

By what you have described to us, it is designed to function safely.
To be totally sure, I would look at the test results on the schedule of tests and confirm, the values of
* r1+r2
* insulation resistance between conductors
* Zs
* and RCD trip times.
And also on the inspection report, that no IP issues were raised, this would be coded.

 

[podgypaul]

Thanks for your replies guys, so in summary, it's safe and will continue to work ?

By what you have described to us, it is designed to function safely.
To be totally sure, I would look at the test results on the schedule of tests and confirm, the values of
* r1+r2
* insulation resistance between conductors
* Zs
* and RCD trip times.
And also on the inspection report, that no IP issues were raised, this would be coded.

Thanks for the advice, i knock nails in for a living, you may as well be talking Latin to me not sure he has had a test done, and we didn't ask for one.

 

[PrenticeBoyofDerry]

You did say in your opening post that electrical test were made by the vendor, I assume these had been passed on to you, if the report had been done correctly then the information asked for should be available.

 

[podgypaul]

You did say in your opening post that electrical test were made by the vendor, I assume these had been passed on to you, if the report had been done correctly then the information asked for should be available.

No, the actual words the previous owner used was "checked" looking at every ones advice and reading other post on this forum it may have been prudent to have a test done.

 

[swampy2]

Knock £200 off your price & then get it checked, guys sparkies issue seems to be cable size only, make sure the cable isn`t covered in insulation.

 

[PrenticeBoyofDerry]

No, the actual words the previous owner used was "checked" looking at every ones advice and reading other post on this forum it may have been prudent to have a test done.

And what would checked mean?
Checks to me would mean that some investigating, a visual inspection and testing of circuits.
How else could it be checked, appliance plugged in and light switches opened/closed?

 

[podgypaul]

No, the actual words the previous owner used was "checked" looking at every ones advice and reading other post on this forum it may have been prudent to have a test done.

And what would checked mean?
Checks to me would mean that some investigating, a visual inspection and testing of circuits.
How else could it be checked, appliance plugged in and light switches opened/closed?

Semantics my friend, lawyers make a living out of semantics, the previous owner said "i got an electrician in to check the wiring, he said everything was ok apart from the shower cable" and the rest is as i posted earlier.

 

[PrenticeBoyofDerry]

Well if there is no observations and schedule of tests to go by, all I can say is the design of circuit is okay, which the vendors electrician seemed to think not.
So not sure how well that bodes with you?
Without a recent report, I would not be able to tell you it was safe, although the circuit design is!