Discuss 6mm2 for 8.5 kw shower in the Electrical Forum area at ElectriciansForums.net

S

scott g

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:  American Electrical Advice Forum

can i fitt 8.5 kw shower using 6 mm2 cable 3m from mains board
only thing is its going through loft insulation more than 100mm
would it be ok to use trunking with insulation on top would this effect cable calculations
 
Electrical2Go - Online Electrical Supplier
This official sponsor may provide discounts for members
K

KFORDHUNTER

  • Thread Starter Thread Starter
  • #2
3 metres of cable, just put 10mm in mate, never know in future they could want 10.5 kw shower.
 
S

Spudnik

  • Thread Starter Thread Starter
  • #3
Def use 10mm with 32A MCB.

Peace of mind as its only 3 meters!!!
 
S

simopesh

  • Thread Starter Thread Starter
  • #4
Hi Scott
Yes, you can use 6.0mm twin and earth cable for 8.5Kw shower. (8.5 multiply by 4.2 equals 35.7 current) 6.0mm cable will be just about enough for 11.5Kw shower if cable ends are crimped or welded for a better and stronger contact. (48.3Amps)
6.0mm cable in wall or trunking ~52 Amps!



can i fitt 8.5 kw shower using 6 mm2 cable 3m from mains board
only thing is its going through loft insulation more than 100mm
would it be ok to use trunking with insulation on top would this effect cable calculations
 
1

12345aob

  • Thread Starter Thread Starter
  • #5
8500/230 =36.9

Table 6E1 in the onsite guide states that a 6mm in an insulated wall has the current carrying capacity of 32 amperes.

I would put in 7.2 shower. (or 10mm cable)
 
S

simopesh

  • Thread Starter Thread Starter
  • #6
I’m using some old fashion maths! Coefficient for single phase (4.2) and for tree face (2.8) done enough showers with 6.0mm cable – no problems so far!

8500/230 =36.9

Table 6E1 in the onsite guide states that a 6mm in an insulated wall has the current carrying capacity of 32 amperes.

I would put in 7.2 shower. (or 10mm cable)
 
S

Spudnik

  • Thread Starter Thread Starter
  • #7
6mm will be fine, but for the sake of 3 meters, and easy access, id put in 10.

But thats me.
 
D

DanBrown

  • Thread Starter Thread Starter
  • #9
Hiya Guys!,
I must be missing something here!

I did the calculation 8500/230 = 37amps

cable current capacities table 6e1 on-site guide -
6mm2 in thermal insulation etc = 32amps
10mm2 in thermal insulation etc = 43amps

Isnt 6mm2 too small and require 10mm2? or does diversity come onto this?
According to diversity table,
1,water heaters (instantaneous) = 100% f.l.
2, water heaters (thermostatically controlled) = no diversity allowable.

What's missing??
Thanks
 
hi dan,
scott is asking for ways to install the cable so that he can use 6mm even though its borderline.
putting it in conduit would help with the thermal insulation problem but for the sake of a few extra quid he needs to do the job right and install 10mm.
you are quite right with your cable calcs but he is looking for the thumbs up to use what he has got which must be 6mm :confused:
 
S

scott g

  • Thread Starter Thread Starter
  • #11
  • ze 0.17 60898 type b 32 6mm2 cable clipped direct with loft insulation on top
  • protected by 30 mamp rcd x1 69 ms
  • thank you for eny feed back
  • its an old lady 87 just had bathroom dones not wont damage to tilles
  • i know it would be ok but boss insists shoud be 10mm
  • im in two minds regs say 10mm common sence says leave it for what she is going to use
  • what would you recommend
  • think boss is thinking of money
 
Once again scott, whatever the big red book says is the way to go ;)
little old ladies shouldnt cloud your judgement :p
 
E

eskimo39

  • Thread Starter Thread Starter
  • #13
I'm with the guys on this one. The big red book is king!!

Have you thought about installing a smaller Kw shower to be compatable with 6mm cable?

If she doesn't want that, I am sure after telling the old dear what a mess an electrical fire can cause, she will be pulling the tiles off for you.
 
S

simopesh

  • Thread Starter Thread Starter
  • #14
I don't think that that would suffice on an EIC.

How are you going to claim that you've complied with BS 7671 if you've got a load greater than the tabulated current carrying capacity of the cable and a protective device rated higher than the tabulated current carrying capacity of the cable?
Very simple and I will certify it too. You’ve got free metres run that means voltage drop will be almost non existent. It will simply allow for a much higher current.
The big red book is a guide only. (Non statutory)
Where is the usual cable burns, is it at the beginning, in the end or in the middle?
According to any physical laws if your connection is good the cable caring capacity does increase. That is one of the main reasons why in other western European countries crimping or soldering the cable ends is absolutely compulsory!
 
you are quite right, the red book isnt statutory but i find that by abiding by it on simple things like cable selection i sleep better at night ;)
the fact that the customer is a little old lady with new tiles is irrelevant and not a viable defence when it all goes wrong :eek:
each to their own i suppose but i will be sticking with the regs safe in the knowledge my install is 100% correct ;)
 
S

simopesh

  • Thread Starter Thread Starter
  • #16
you are quite right, the red book isnt statutory but i find that by abiding by it on simple things like cable selection i sleep better at night ;)
the fact that the customer is a little old lady with new tiles is irrelevant and not a viable defence when it all goes wrong :eek:
each to their own i suppose but i will be sticking with the regs safe in the knowledge my install is 100% correct ;)
My install of 6.0mm twin and earth cable for 8.5Km consumable on a 3 metres run will be 100% safe and secure as well!
 
W

WarrenG

  • Thread Starter Thread Starter
  • #17
But what is statutory is the requirement to make reasonable provision in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury.

If you disregard the current carrying capacities in BS 7671, which are not arbitrary, have you made reasonable provision?


Read 134.1.4 - it's a fundamental principle of BS 7671 that joints will be properly made, and therefore the capacities tabulated in Appendix 4 will be based on the assumption that they have been.



But in what way does it comply with BS 7671?

I see the DIYer Banallsheds is starting to create arguements on this forum also.

Why are you looking to comment on a document that you don't consider to be relevant (BS7671) and more importantly why worry about an EIC when you have clearly stated on other forums that its not needed?

It appears to me that you seem to visit alot of the forums to cause problems with the members for your own kicks. Why bother?
 
simopesh,
i think you are missing the point here.
6mm doesnt meet the requirements of bs7671 which we all work to.
why would you want to install 6mm when you can install the correct 10mm and charge the correct amount for the job too.
the fact that the customer is old and has new tiles has no bearing on us as electricians to feel that because she doesnt want the decor damaged we must bend the rules.
you are quite right in saying that your way will work and i dont dispute that but what will your defence be if it did all go wrong??
as i said each to their own but i feel by keeping to the regs i will always have a clear conscience should the unthinkable happen
 
C

coxy

  • Thread Starter Thread Starter
  • #19
Hi Guys,
Read all the comments,where as i do feel that bs7671 does go over the top, i have just spent £280 on 17th edition course £100 on books,£450 to renew nic.I will stick to the regs as i have to and anyone else doing electrical instrallation work should do so as well.Its the only way to try to get standards up.It amazes me that for a few pounds more people compromise safety.Why is it our industry allows this i thought part p would sort it out,but it has not !!!
 
well said coxy.
i think you will find most electricians do adhere to the regs, that is after all what they are there for.
like you say theres no point paying out on latest edition courses if you dont intend to use the book properly. :confused::confused:
 
C

coxy

  • Thread Starter Thread Starter
  • #21
Hi Flukey,
You may be right but the real problem is people walking into b&q seeing on a big board how to connect lighting circuits etc.They do not explain the regulations to these people,then when you try to do a proper install and then mention the price you always get funny looks !!! one guy recently called me in because his kitchen install was a complete balls up,said if i could first fix for him could he second fix to save money !!! Would he say that to a heating engineer - pipes are in, i will fit boiler - no.Most sparkys have spent years doing a good job unfortunatly some people still do not understand how skillfull you sometimes have to be,and knowledge we have to learn.Thats it moan over.!!
 
S

sparkyork

just to have me two pennies worth, i wouldnt even contemplate putting 8.5kw shower on a 6mm, the regs may not be statutory but when the **** hits the fan the court is gonna ask if it was done to current regs, your reply would be no sir, then its see ya later enjoy getting bent over in jail!

7.2kw is all i would put on a 6mm, be safe, keeo others safe and dont increase your chances of going to jail, is it really worth it???
 
S

scott g

  • Thread Starter Thread Starter
  • #23
has anyone had to install 16mm for shower ref 101
10.5kw shower
 
HI SCOTT,
DEPENDING ON THE CONDITIONS THIS IS VERY POSSIBLE. I KNOW IT SOUNDS MAD NEEDING A 16mm TO RUN A SHOWER AND THE CONNECTIONS WILL BE A NIGHTMARE, BUT IF THE CALCULATIONS TELL YOU THAT IS THE CASE THEN SO BE IT. IN THIS CASE YOU HAVE TO LOOK AT YOUR INSTALLATION METHOD AND SEE IF RE ROUTING IS MORE PRACTICAL TO KEEP THE CABLE TO A SENSIBLE SIZE. ONCE AGAIN DO THE SUMS, REFER TO THE REGS AND YOU CANT GO WRONG ;)
 
Last edited:
K

KFORDHUNTER

  • Thread Starter Thread Starter
  • #25
I to work to current regs, have done my updated 17th course, registered with niceic as domestic installer, have all relevant insurances etc etc.

However i think a point has been missed here, you can put whatever shower you want on a 6mmt+e, just back it up with a 32a mcb, then when it surpasses this amount it will take the breaker out, cable safe.

The real issue is whether or not we want to do the job properly or not. for those that do don't bother arguing with those that don't. They are not going to change their minds and all they will do is hoover up the work we refuse to do.

I sometimes wonder who the real fools are!!!!!!
 
Thats a very relevant opinion.
Not sure i would want to keep getting calls from a customer though when their breaker keeps tripping when i could have installed the job correctly in the first place. :eek:
If my workload gets that low that i need to consider competing with sparks that use inferior equipment then i will review my policy at that time.;)
Until that day arrives i for one will carry on installing every job under the scope of the regs as they are intended :)
 
C

coxy

  • Thread Starter Thread Starter
  • #27
When installing any cables now make sure you stay clear of insulation.If needed suspend cables in loft on cable tray then drop down,yes ridicilous but have you ever been in a loft in the middle of summer ????
The regs are there to make sure of a proper installation - simple !!
Yes they are over the top, as i said before but the more regs the better as hopefully it will stop the cowboy sparks !!!

Hi, on what kfordhunter said - think ! when would the 32amp mcb trip on overload ??
Look at the time/current tables - you may be surprised !!! to see how much it could take therefore the cable is as well !!
 
Last edited by a moderator:
S

simopesh

  • Thread Starter Thread Starter
  • #28
Hi Guys,
Read all the comments,where as i do feel that bs7671 does go over the top, i have just spent £280 on 17th edition course £100 on books,£450 to renew nic.I will stick to the regs as i have to and anyone else doing electrical instrallation work should do so as well.Its the only way to try to get standards up.It amazes me that for a few pounds more people compromise safety.Why is it our industry allows this i thought part p would sort it out,but it has not !!!
Compulsory “safety” does not come from cable size, however, it does come by adding an additional safety (in this case absolutely compulsory) called Residual Current Device!

When installing any cables now make sure you stay clear of insulation.If needed suspend cables in loft on cable tray then drop down,yes ridicilous but have you ever been in a loft in the middle of summer ????
The regs are there to make sure of a proper installation - simple !!
Yes they are over the top, as i said before but the more regs the better as hopefully it will stop the cowboy sparks !!!

Hi, on what kfordhunter said - think ! when would the 32amp mcb trip on overload ??
Look at the time/current tables - you may be surprised !!! to see how much it could take therefore the cable is as well !!
 
Last edited by a moderator:
S

simopesh

  • Thread Starter Thread Starter
  • #30
simopesh,
i think you are missing the point here.
6mm doesnt meet the requirements of bs7671 which we all work to.
why would you want to install 6mm when you can install the correct 10mm and charge the correct amount for the job too.
the fact that the customer is old and has new tiles has no bearing on us as electricians to feel that because she doesnt want the decor damaged we must bend the rules.
you are quite right in saying that your way will work and i dont dispute that but what will your defence be if it did all go wrong??
as i said each to their own but i feel by keeping to the regs i will always have a clear conscience should the unthinkable happen
I do know what I’m talking about. Float of electrons and multi-core cable are laws of physics that I can talk on a much higher level.
What will happen if you install a shower with 10.0mm cable with loose connections? I’m absolutely shore that you know the answer.
In accordance with the current 17th edition the supply tails from meter to board are bound to be 25.0mm double isolated tales. Ok, but how does EDF or the rest of the suppliers comply with the above? Well, I’m afraid to say but they don’t. Some of the domestic households are with 10.0mm main supply piro cable with 4-6 storage heaters, immersion heaters (Low and Normal), electric cocker shower and more. Did you ever ask yourself how do the mains last when people override the tele-switch and everything is pushed to its limits? Believe me it does last!
I know by pure calculations that cable current capacity is largely downgraded for safety; however, with the current technologies its safety issues are unnecessarily exaggerated!
Regards
 

Reply to 6mm2 for 8.5 kw shower in the Electrical Forum area at ElectriciansForums.net

Aico Carbon Monoxide Detectors
This official sponsor may provide discounts for members
Top Bottom