Shower

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I have just ripped out my bathroom ready for a total re-plaster job and new suite. Under my bath the cable for the shower run freely by the side of the bath so I can see how thick the cable is. I want to know if there is any way to measure the capacity, i.e, is it 8.5 or possibly 9.5+ KW. I have an 8.5 kw shower to put in, if I can put a high kw in I will. How can I check? Thanks in advance for advice.
 
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see sticky for refernce it has a guide on the outside diameter of cables, then tell us what size cable you have
 
I'm really sorry, I have had a look and cannot find what you have suggested, is there any chance you would mind posting a direct link. Thanks ever so much.
 
Judging what cable size you have:

1mm² CSA T&E has overall dimensions of 7.8mm x 4.25mm
1.5mm² CSA T&E has overall dimensions of 8.2mm x 5mm
2.5mm² CSA T&E has overall dimensions of 10.3mm x 6mm
4mm² CSA T&E has overall dimensions of 11.9mm x 6.25mm
6mm² CSA T&E has overall dimensions of 13.5mm x 7mm
10mm² CSAT&E has overall dimensions of 17.1mm x 10mm
16mm² CSA T&E has overall dimensions of 19.4mm x 10mm

Source: http://www.tlc-direct.co.uk
 
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Looking at that table I have probably got:

10mm² CSAT&E has overall dimensions of 17.1mm x 10mm

It could possibly be one higher but I wouldn't like to push it. Would I be ok with a 9.5kw or slightly higher shower?
 
It depends how its installed, the length etc, but 10mm² shouldn't present a problem, its very rare anything bigger is needed for a shower, its the 6mm² which is troublesome, it was the norm when showers were lower powered but is not suitable for today's high output units

So your new shower shouldn't be a problem on your existing cable :)
 
Well the cable runs freely from the CB through an external opening/internal store then goes under floor and then into bathroom, realistically there is probably 10 - 15 meters of cable, apporximately 2 metres behind plaster running alongside the cold water feed. Whats the highest KW I could use in the worst case?
 
Cable will take a 10.5kW comfortably. But as this is in a bathroom you should have it installed professionaly, making sure all other considerations are met such as bonding and earth loop impedance.
 
A plumber is going to swap the original shower for the new one, its just that we played it safe and purchased an 8.5 as we could not see the cabeling. When I stripped out the bathroom we found the shower cable running underneath te bath and I just thought it looked like quite thick cable. To get a better idea what actual cable I have I'm going to pay a visit to B&Q to look at cable thats packaged up to see the difference in size betweem 6mm2 and 10mm2
 
Had a good look at the cable now. The cable that runs from the consumer unit is 6mm2 as it has a single copper core for the earth and is slightly thinner then the cable running from the isolator to the shower that has multiple copper core earth. The running of the cable is pretty striaght forward, I can trace it from the consumer unit up through an external store into the floor and then into the bathroom. I'm going to re-run the cable by attaching it to the old cable and pulling it through. My next question is what trip ampage do I need in the consumer unit. It currently has a 32 amp trip wired for the shower. Thanks for advice.
 
the shower consumes 36.95A - you need a 40A MCB.

8500w/230v=36.95a
p / v = i
 
whitfields guide said:
Note on Supply Voltage Level
For many years the supply voltage for single-phase supplies in the UK has been 240V +/- 6%, giving a possible spread of voltage from 226V to 254 V. For three-phase supplies the voltage was 415 V +/- 6%, the spread being from 390 V to 440V. Most continental voltage levels have been 220/380V.

In 1988 an agreement was reached that voltage levels across Europe should be unified at 230V single phase and 400V three-phase with effect from January 1st, 1995. In both cases the tolerance levels have become -6% to +10%, giving a single-phase voltage spread of 216 V to 253 V, with three-phase values between 376V and 440 V. It is proposed that on January 1st, 2003 the tolerance levels will be widened to +/- 10%.

Since the present supply voltages in the UK lie within the acceptable spread of values, Supply Companies are not intending to reduce their voltages in the near future. This is hardly surprising, because such action would immediately reduce the energy used by consumers (and the income of the Companies) by more than 8%.

In view of the fact that there will be no change to the actual voltage applied to installations, it has been decided not to make changes to the calculations in this book. All are based on the 240/415V supply voltages which have applied for many years and will continue so to do.

In due course, it is to be expected that manufacturers will supply appliances rated at 230 V for use in the UK. When they do so, there will be problems. A 230 V linear appliance used on a 240 V supply will take 4.3% more current and will consume almost 9% more energy. A 230 V rated 3 kW immersion heater, for example, will actually provide almost 3.27kw when fed at 240 V. This means that the water will heat a little more quickly and that there is unlikely to be a serious problem other than that the life of the heater may be reduced, the level of reduction being difficult to quantify.

Life reduction is easier to specify in the case of filament lamps. A 230 V rated lamp used at 240 V will achieve only 55% of its rated life (it will fail after about 550 hours instead of the average of 1,000 hours) but will be brighter and will run much hotter, possibly leading to overheating problems in some luminaires. The starting current for large concentrations of discharge lamps will increase dramatically, especially when they are very cold. High pressure sodium and metal halide lamps will show a significant change in colour output when run at higher voltage than their rating, and rechargeable batteries in 230 V rated emergency lighting luminaires will overheat and suffer drastic life reductions when fed at 240V

There could be electrical installation problems here for the future!


Its further complicated in the case of showers because the "headline rating" is at 240v, Consistancy? We don't need no stinkin' consistancy... :LOL:
 
we have to design at 230, since this is the "official" harmonised voltage with europe, and current is higher at 230v.

but you are right, most of the UK still runs at 240v.
 
crafty1289 said:
we have to design at 230, since this is the "official" harmonised voltage with europe, and current is higher at 230v.
But when you do, make sure you use the ratings for equipment at 230V, not 240V.

crafty1289 said:
the shower consumes 36.95A - you need a 40A MCB.

8500w/230v=36.95a
p / v = i
Almost certainly an "8.5kW" shower is 8.5kW at 240V, and in the small print the 230V rating will be 7.8kW...
 

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