this cable size cant be right , can it?

[thatbloke]

8.5 kw shower , 12 meter run , cable clipped straight to a wall , not bunched up , ambient temp 30 , one circuit.

its saying i need 4mm cable.

i really did think i needed 10mm cable.

http://www.tlc-direct.co.uk/Technic...230&length=12&submit=Calculate+Min+Cable+Size

 

[ricicle]

4mm² would be ok, but only a fool would nowadays run in that for a shower. Even 6mm² is becoming less frequently used for new installs.

Think of spare capacity for the future upgrade.

Come to think of it why are you bothering with a 8.5kw shower anyway ?

 

[SUNRAY]

8.5 kw shower , 12 meter run , cable clipped straight to a wall , not bunched up , ambient temp 30 , one circuit.

its saying i need 4mm cable.

i really did think i needed 10mm cable.

http://www.tlc-direct.co.uk/Technic...th=12&submit=Calculate+Min+Cable+Size[/QUOTE]

Weellllllll !

The 4mm calcs have it as ok.....

Buuutt......

Next year or 3 when the shower breaks down, the reaction will be 'well it wasn't that good, lets replace it with a better one, in fact a 8.5KW probably will not be available.

The better one will be 10-11KW which the same calculator will say 6mm is marginal.

The additional cost of 10mm over 4 mm now will be negligible compared to the hassle to replace it later and will allow upgrade to 14KW.

 

[thatbloke]

is an 8.5kw shower a bit pants then? i wont be upgrading it at all , its just a temporary solution until i get my gas boiler put in which will be 3 or 4 weeks , perhaps sooner.
what can i expect from an 8.5 kw shower then? i thought it was all to do with flow rate? ive got very good mains pressure ,well above average.

if i do go with 8.5kw would i be better to use 6mm? best to have it and not need it rather than need it and not have it.

 

[electronicsuk]

is an 8.5kw shower a bit pants then? i wont be upgrading it at all , its just a temporary solution until i get my gas boiler put in which will be 3 or 4 weeks , perhaps sooner.
what can i expect from an 8.5 kw shower then? i thought it was all to do with flow rate? ive got very good mains pressure ,well above average.

Flow rate is pretty irrelevant, as even a top-end domestic electric shower in terms of power does not require a particularly high flow rate. There's only so much water you can heat to a given temperature when you've only got a fixed amount of power to put in.

If it's only temporary then you may as well go for the cheapest possible cable and shower.

 

[Steve]

what can i expect from an 8.5 kw shower then? i thought it was all to do with flow rate? ive got very good mains pressure ,well above average.

Indeed, and the faster you push the water through the shower, the colder it will be! Electric showers run at full wattage (8.5kw) all the time they are on. The "temperature" dial alters the water pressure through the heater, such that if you turn it "up", the water slows down, and if you turn it "down", the water gets faster!

8.5kw showers are ok, we used to have one. But I wouldnt fit anything less than 9.5 now.

If this is temporary and will be removed in a few weeks, then use 6mm². But if its a temporary shower and you wish to keep the cable in situ for future use, use 10mm².

 

[ban-all-sheds]

If you assume the water comes in at 10°C and you want it at 40°C, then an 8.5kW shower will provide a flow rate of about 4l/minute.

To put that in perspective, ordinary showers are recommended to be no more than 9l/minute, to conserve water.

 

[Diyisfun]

For a 3 week period, I can go without a shower, join a local gym.

 

[thatbloke]

cheers Steve , 8.5 on 6mm it is.
ive been living on a building site for 3 weeks now with no hot water , they wouldnt let me through the front door of a gym.

 

[thatbloke]

If you assume the water comes in at 10°C and you want it at 40°C, then an 8.5kW shower will provide a flow rate of about 4l/minute.

To put that in perspective, ordinary showers are recommended to be no more than 9l/minute, to conserve water.

i cannot remember what my mains flow rate was but if its too much i can always partially close the service valve to slow it down , or would a leccy shower reduce water pressure anyway? its only a cheapo unit.

 

[Steve]

or would a leccy shower reduce water pressure anyway? its only a cheapo unit.

Yes. Thats how they work.

If you want hotter water, it slows the water down so that it spends longer in the heater.

 

[thatbloke]

or would a leccy shower reduce water pressure anyway? its only a cheapo unit.

Yes. Thats how they work.

If you want hotter water, it slows the water down so that it spends longer in the heater.

thats what i thought , hopefully an 8.5kw will give me a bit more than a dribble , i am so looking forward to this , i have never been this excited over a potentially pants shower before.
it being a new unit it should work ok though ,i would hazard a guess that its usually when limescale builds up inside them that they suffer from reduced performance.

 

[Stoday]

thats what i thought , hopefully an 8.5kw will give me a bit more than a dribble , i am so looking forward to this

Try out how much of a dribble with a tap.

4 litres per minute fills a wine bottle in 12 seconds. Adjust your tap until it takes 12 seconds to fill a wine bottle and that's the flow you'll be able to get (unless you want a cold shower).

 

[SUNRAY]

is an 8.5kw shower a bit pants then? i wont be upgrading it at all , its just a temporary solution until i get my gas boiler put in which will be 3 or 4 weeks , perhaps sooner.
what can i expect from an 8.5 kw shower then? i thought it was all to do with flow rate? ive got very good mains pressure ,well above average.

if i do go with 8.5kw would i be better to use 6mm? best to have it and not need it rather than need it and not have it.

If the shower unit AND the cable are literally only going to be there for a month and then ripped out again, then use 4mm, it is fully rated [just] for the job so there is no point in wasting your money. If there is any chance that the cable will stay in for future use then use 10mm.

The 8.5KW will be fine for the short term fix.

My first electric shower unit was 6KW and we thought that was fantastic till it packed up and was replaced with a 7.2KW unit then 9KW now 10.5KW. where will ist end?

 

[londonboy]

Use 6mm, remove it when your finished then strip it and scrap it