Splitting supply to a shower!!!

[carhartt kid]

All sorted... My sparky mate Buzz Lightgear came over and slung in some 2x60amp connectors, and two lenghts of 6mm to my ceiling pull switch!!! Took a photo of it, signed it off and sealed it all in under the floor boards....... Whole lot took him 30 mins..and cost me a bottle of Vino!!!

[ban-all-sheds]

So the pullcord interrupts both Live and Neutral!

Excellent!

Just as it should be!

Nothing wrong there!

Just measured the cable and its 6mm (thats 5 x 1mm strands in a harmonised sheath, then a 1mm outer grey sheath)

How did you measure the cable?

First you said it was 10mm, now you say it's 6mm...

I see you got a "sparky mate" to sort it in the end, so hopefully he has used the right sized cable, but given that he went for the inferior solution of extending the cable rather than doing a proper job, and has left junction boxes sealed under floorboards, then I'm not entirely convinced he's any good....

Also, what is the total length now of the cable run from the CU to the shower?

[ban-all-sheds]

Also dont forget cross bonding in your bathroom,linking, hot,cold,towel rail/radiator if present,metallic light fitting,shaver point and shower together with a loop of 4mm green/yellow insulated cable.

Ooh no - don't bond to a metallic light fitting.

1) If it's a Class I item then the body will be an exposed-conductive-part, therefore connected to the cpc of the lighting circuit, and therefore bonded via that.

2) If it's Class II, then the body is not an exposed-conductive-part nor an extraneous-conductive-part, and therefore does not require bonding.

And the advice to bond radiators and towel rails etc ignores the possibility that they could be fed by plastic pipes and are therefore might not extraneous-conductive-parts....

[ban-all-sheds]

as for the bonding my spark tells me to bond, basin, bath and rad using 4mm earth back to the light fitting

Get a new spark.

[ban-all-sheds]

Tim, you are now meant to use 230V as your calculation voltage, not 240 or 250, as i suppose the way they look at it is if you work it out with 230V thats the worst case scenario, cant get worse than that really.

I always think you should use the figures that the appliance manufacturer gives you.

So if he quotes the power consumption at 240V (which AFAICT is the case for 99.999999999% of shower makers) use 240V.

It makes no sense to use the 240V rating of an appliance in a 230V calculation.

If they also quote a 230V power consumption, then you can use that. If not, then a pretty good approximation for what the current would be at 230V is (where P is the quoted power consumption at 240V):

P x 230
240²

As for the table mr hinton, that table relates to flexible cables only , as you cannot obtain 1.25mm twin and earth LoL, any cable which has fine stranded cores, has a slightly higher current carrying capacity than a normal stranded core cable.
Will try and find a table somwhere which shows the sizes and ratings.

Anybody who wants such a table will find it in the Wiring Regulations, Table 4D5A, or the On-Site Guide as Table 6F.

[ultimatehandyman]

Also dont forget cross bonding in your bathroom,linking, hot,cold,towel rail/radiator if present,metallic light fitting,shaver point and shower together with a loop of 4mm green/yellow insulated cable.

Ooh no - don't bond to a metallic light fitting.

1) If it's a Class I item then the body will be an exposed-conductive-part, therefore connected to the cpc of the lighting circuit, and therefore bonded via that.

2) If it's Class II, then the body is not an exposed-conductive-part nor an extraneous-conductive-part, and therefore does not require bonding.

And the advice to bond radiators and towel rails etc ignores the possibility that they could be fed by plastic pipes and are therefore might not extraneous-conductive-parts....

I am sure that all the documents out there are specifically designed to confuse people.

Paul Cook from the IEE published a PDF booklet on earthing plastic pipes and it says
" The protective conductors of
all power and lighting points
within the zones must be
supplementary bonded to all
extraneous-conductive-parts
in the zones, including metal
waste, water and central
heating pipes, and metal
baths and metal shower basins."

?

[ban-all-sheds]

I am sure that all the documents out there are specifically designed to confuse people.

Well - no, they are not, but they might be confusing to people who don't understand what they mean. They are written, not to confuse, but to be precise.

Paul Cook from the IEE published a PDF booklet on earthing plastic pipes and it says
" The protective conductors of
all power and lighting points
within the zones

My first point above - it is the protective conductors that are connected to the bonding, not the bodies of metallic light fittings.

must be
supplementary bonded to all
extraneous-conductive-parts
in the zones, including metal
waste, water and central
heating pipes, and metal
baths and metal shower basins."

And here you must know what an extraneous-conductive-part is. NICEIC have a good document here explaining it.

The examples in Paul Cook's list are things which must be bonded if they are extraneous-conductive-parts, it is not saying, for example, that a metal bath is an extraneous-conductive-part.

[skiking]

I think its to do with 'official' organisations unable to use Plain English. Just to make themselves sound a little more important

[tim'll fix it]

as for the bonding my spark tells me to bond, basin, bath and rad using 4mm earth back to the light fitting

Get a new spark.

a very helpful reply thanks

[ban-all-sheds]

Sorry - it was bit of a flippant reply.

But the thing is that advice is so incomplete, ignoring as it does the whole topic of whether items really are extraneous-conductive-parts, as to be worse than useless.

It's not a case of "better safe than sorry", or "can't do any harm" - if you apply supplementary equipotential bonding to an item that is not an extraneous-conductive-part then you have made things less safe, not more.

[tim'll fix it]

i seem to only fit concealed valves with the pipe work buried and he claims I dont have to bond then, but I still do