Load Rating of Electrical Cable?

[Lord0]

Hi there,

My electric shower died. I'm pretty sure it was a 9.5kW - it certainly has this stamped on the "element". I was considering *maybe* replacing it with a 10.5kW version. My obvious concern is whether the cable from the fuse box will handle the load. The cable has the following stamped on it:

"BASEC BS 6004 ATOM KABLO 2x6+2.5"

I've searched around a bit, google, and can't find anything which would indicate the load the cable can take. I'm guessing the important bit is "2x6+2.5"

As ever thanks in advance

Lord0

[adsie]

10% is a relatively small change in power. The fuse should blow a long time before the cable becomes dangerously hot. If your cable got hot with the old element then you already had a problem. If it didn't then the bigger element won't make any detectable difference.

Adsie.

[tiscali]

10kW is one helluva heating element!

[Lord0]

Is it? Is my use of "element" incorrect? For example (9.5kW):

[Lurch]

On 12 Mar 2007 10:15:50 -0700, "Lord0" mused:

It would appear that you have 6mm twin and earth which, unless your run from the shower to the consumer is particularly short, is generally inadequate for 9.5kw. I tend to stick to 8.5kw showers on

6mm, anything over 8.5kw gets a 10mm supply cable.

The cable rating depends on many factors though, length, ambient temperature, how many other cables it's run with, whether it's wrapped in insulation and a few others.

[Lord0]

I was reading a book which said "showers" should be wired in with 2x10 cables and not 2x6. Am I in danger of fire etc by using 2x6 cable? Note: it's been working okay for years and years.

[Lord0]

Being that I've had no problems with the existing 9.5kW shower on the

6mm will it be safe to install a new 9.5 shower on the existing 6mm?

[Dave Plowman (News)]

[Owain]

2 conductors of 6mm and a cpc of 2.5mm?

Owain

[Lurch]

On 12 Mar 2007 12:17:39 -0700, "Lord0" mused:

Just because it works doens't make it right. as I said though, it may be fine, it may not, many facors determine the rating of the cable.

[Lord0]

Well pluging the details of my cable run into the calculator on the link above gives a required cable size of 6mm! Hmmm

FYI - Twin and Earth, clipped direct to wall (well all but 1.5m which is in trunking), 240V, 9m of cable, 9.5kW load.

So I still kinda confused. I seem to be getting mixed messages.......the 6mm cable has been in place, and used daily, for the last 4 or 5 years.....

[Alistair Riddell]

6 mm T&E is officially rated at 46 amps when clipped direct, (=11 kW @ 240 V) or 38 amps (=9.1 kW) when enclosed in conduit.

So, in terms of current rating, the existing cable in fine for 8.5 kW load but slightly underrated for 9.5 kW load.

If the cable is clipped direct then it should be a fairly straightforward job to replace it, no?

If your 'fuse box' contains fuses of the rewireable type then it should probably be replaced before thinking about installing an even bigger electric shower.

[Lord0]

You'd think so eh? But it goes through the ceiling into loft etc. thanks for the feedback tho

[fred]

In article , Lord0 writes

Showers are one of those situations where you can get by with quite a bit as they are used for a relatively short period, overloaded circuits don't quite reach critical temperatures and as a result things work fine for years. I'd say you were skating pretty close with a 9.5kW shower on 6mm2 and

10.5kW would be a step too far. In your place I would take the advice of Lurch who AIUI works daily as an electrician and so has seen what can go wrong and recommends a re-wire with 10mm2.

Re the TLC calculator, is your cable really surface mounted, ie visible for the majority of its length and not enclosed at all?

BTW: When they do go just slightly wrong there's loads of current to melt all in the way to a guey (usually smoking) mess.

[Lord0]

I have definitely ruled out the 10.5kW :)

I know I *should* rewire but TBH it would be a pain in the a$$. Obviously not as much as a pain in the a$$ as a "meltdown". The reason I am thinking about *not* rewiring i.e. keeping the 6mm cable is that it has been working okay, with no sign of melting etc, on a 9.5kW shower for about 5 years.

Yes. It runs from the consumer box, in ground floor, surface mounted, then through ceiling/floor into upstairs bedroom (here it is in trunking from floor ot ceiling), then into loft where it is surface mounted and then drops down into bathroom from loft (again surface mounted) i.e.

Loft (surface mounted) ==>==============>======= | | Shower | Bedroom (in trunking) * | =========== | | Consumer Box (surface mounted) |

[Andy Burns]

By which you mean _no_ it is partially in trunking!

You have asked for advice, been told that the cable is at best marginal for your current shower, yet seem determined not to replace it despite increasing the power for a new shower.

Why not take the best suggestion, especially when you know the possible consequences?