no the other shower will come of the cu down stairs.can you only have one shower of a cu?
Cable in wall cavity
- Thread starter talyllynman
- Start date
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Err - can you multiply the current demand of a shower by 2?jbonding said:
having two showers off a CU is somewhat borderline especially when you consider other loads
having said that it may well be that the water pressure is too low for both showers to stay on at the same time anyway
one option is to use a supply changeover switch wired in reverse so only one shower can be on at a time (i think you can get some more automated switchover devices for this kind of thing but i don't think they are cheap).
having said that it may well be that the water pressure is too low for both showers to stay on at the same time anyway
one option is to use a supply changeover switch wired in reverse so only one shower can be on at a time (i think you can get some more automated switchover devices for this kind of thing but i don't think they are cheap).
so whats the best way to power the loft for a socket ring main, lights and shower would it be easier to feed of the lights down stairs and extend the socket ring main and run the shower of the cu down stairs, both showers wont be on at the same time. cheers plugwash. PS hes aware of part P and hes getting it checked when its done.
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if you are going to run up the outside of the house i would say use 16mm 3 core SWA preferablly XPLE insulated.
at the main fuseboard end terminate this into a 60A metalclad switchfuse and connect to existing tails with henly blocks (probablly best to get an expert to do this pulling the service fuse isn't generally reccomended for diyers)
at the loft end fit a metalclad CU of appropriate size and type (split load is probablly best)
at the main fuseboard end terminate this into a 60A metalclad switchfuse and connect to existing tails with henly blocks (probablly best to get an expert to do this pulling the service fuse isn't generally reccomended for diyers)
at the loft end fit a metalclad CU of appropriate size and type (split load is probablly best)
That's very easy to say.jbonding said:
How do you absolutely guarantee that it can't happen, though?
cheers plugwash, hes decided not to go up the outside and hes gonna chase out on the inside, he got 25mm cable of site can he use that. hes not gonna be doing any of the connecting up to the fuse boards he wants the right wires in so he can board and plaster. cheers, dont know if he wants the second shower but he wants the power to it just in case. he originally wanted six showers but couldnt guarantee theyde be on at once 
25mm will be fine as long as its a suitable type
dunno if tail type cable would be a good idea over that kind of length. I guess DI tail is no worse than T&E on the other hand its a very large size of cable and i dunno if the planned route is completely inside the permitted routes for unprotected cables so steel wire armoured may still be a more sensible choice.
dunno if tail type cable would be a good idea over that kind of length. I guess DI tail is no worse than T&E on the other hand its a very large size of cable and i dunno if the planned route is completely inside the permitted routes for unprotected cables so steel wire armoured may still be a more sensible choice.
B
Big_Spark
ban-all-sheds said:
How on Earth do you arrive at 29kW from the comment "Two showers, five sockets and a couple of lights"
29kW is 126A@230V and 120A@240V
That will not necessarilly require a second supply in, but it should be done with a lot of thought, the loading will still potentially be significant and the existing supply may need uprating in order to supply it.
Has he got cable with 25mm² conductors, or something which measures 25mm across?jbonding said:
jbonding - plug makes a point here which is literally of life and death importance.plugwash said:
If your friend is planning to conceal this cable then he must make sure that he follows the rules for doing so:
http://www.niceic.org.uk/downloads/C5-43.pdf
http://www.niceic.org.uk/downloads/concealedcables.pdf
2 x 10+ kW showers = 20+kWFWL_Engineer said:
1 x 32A ring final = 7.63kW
1 x 6A lighting = 1.38kW
Yes, I do know that that is not how you work out maximum demand, but I just felt that jbonding needed a wake-up call to shock him out of his vagueness - he didn't seem to think that any of this was at all significant - thinking you could just add showers willy-nilly, being surprised when told that even 2 of them would be a struggle and solving that by simply deciding that they would never be used together, doing all this on behalf of a friend who originally thought he could have 6 showers....
the six showers was sarcasm, ban all sheds if youve got nothing but scare tactics dont bother commenting, i know electric kills, if you go back through the posts you see no live power involved. b.a.s said ( being surprised when told that even 2 of them would be a struggle and solving that by simply deciding that they would never be used together,) is it just a struggle or possible? b.a.s said (but I just felt that jbonding needed a wake-up call to shock him out of his vagueness - he didn't seem to think that any of this was at all significant ) im on a forum asking for advise about electrics (HELLO)
Hello.
very few domestic supplies are adequate to support two electrically heated showers simultaneously, or if so only when nothing else is on. (being 60, 80 or possibly 100A fuse absolute max.)
Unless you can guarantee to the contrary there needs to be a positive mechanism (not just hoping) that they will never be switched on together. Otherwise, when you have visitors coming for dinner, and the oven is on and you both dive in to a quick shower to freshen up in the hour before you expect the doorbell to ring , you may find yourself in the dark and cold calling out the electricity board to replace the main fuse.
Hope that helps explain the concerns.
Aditionally many makes of domestic consumer units specify not more than one 40A load is allowed, for reasons of overheating the bus-bars.
very few domestic supplies are adequate to support two electrically heated showers simultaneously, or if so only when nothing else is on. (being 60, 80 or possibly 100A fuse absolute max.)
Unless you can guarantee to the contrary there needs to be a positive mechanism (not just hoping) that they will never be switched on together. Otherwise, when you have visitors coming for dinner, and the oven is on and you both dive in to a quick shower to freshen up in the hour before you expect the doorbell to ring , you may find yourself in the dark and cold calling out the electricity board to replace the main fuse.
Hope that helps explain the concerns.
Aditionally many makes of domestic consumer units specify not more than one 40A load is allowed, for reasons of overheating the bus-bars.
OK - but that wasn't obvious..jbonding said:
You asked a question with none of the information needed to answer it - it was impossibly vague.
When asked to elaborate you replied with more utter vagueness that did not provide any more information.
You were asked a second time not to be so vague, and you came back with a requirement where the breaker capacities totalled approx 125A.
What I did was not "scare tactics", i.e. it wasn't meant to "scare" you - it was supposed to shake you out of your complacency - your vagueness, and lack of thought, and inability to add up loads seemed to me to indicate that you were not taking any of this seriously.
What on earth does that mean? Ignoring the fact that you have not said "no live power involved", it's a meaningless concept, unless you're trying to say that what your friend plans to do is to install the cable, and the CU in the loft, and the circuits and accessories and appliances in the loft, but never connect it, or have it connected, to the supply. Which I doubt.
So what does "no live power involved" mean, and in what way is it relevant to any of the advice you've been given?
You tell me - 2 showers on together is 80-90A. What is the size of your friend's service fuse? What else would he like to have on at the same time?
Yes, you are, and you're getting advice, even if you seem not to like all of it. But you can't get useful advice without providing useful input, and the words "stone" and "blood" come to mind there.
Anyway - a bit more advice for you:
There's more to Part P than "getting it checked when it's done". Doing that will not meet the requirements of Part P of the Building Regulations and leaving it until then will be too late to meet the requirements of Part P of the Building Regulations....
unless youve got six showers, then it wasnt obvious.cheers mapj starting to understand it a bit more, b.a.s when i said no live wires i meant hes putting the wires in place, he needs, and a spark is gonna take it from there. so start from scratch and tell me how to power the loft for what i mentioned instead of jumping onto it when you notice a mistake, lets see if you can say anything positive .cheers
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