regs advice on shower cct

[NozSpark]

Well, I've quoted the overload regs while Robin quoted the fault protection regs:blushing

 

[steptoe]

but, they both concur that it is permissible,

yes?

 

[NozSpark]

This is also the very first time I've opened my BGB,,, so it's now officialy soiled

 

[steptoe]

This is also the very first time I've opened my BGB,,, so it's now officialy soiled

2nd hand,

I'll give you 20quid for it.

 

[Robin Spark]

well that was obviously a sh*7 example then? wasnt it? :Blushing ---------- Post Auto-Merged at 00:04 ---------- Previous post was made at 00:03 ----------

thats irrelevant, as long as the OCPD is low enough to protect the cable.

Steps thought you might have come back with 1.5mm MICC as get out of jail clause lol!

 

[Electroglow]

Hang on this is doing my head in lol....

Right the lay out...

100A main fuse dno.

100a main switch in cu or 80a

The 6mm cable then is feed from the 100a main switch in the cu same incoming side as the tails...

My q is how would this 6mm be protected as it can't take a load of over 40a

Although as the max load on the mcb is 40a then it wouldnt ever over loa as the pro device will trip

 

[Manator]

The shower can take say 40amps max over say an hour, this would not impede the draw, and would never build sufficient loss or heat to warrant the 100amp main fuse to detect any problem. the 40amp mcb or rcd would operate before any 100amp supply fuse would, therefore, whilst not best practice, it is still protected.

 

[SPECIAL LOCATION]

What about the CSA of the protective conductor?

Do I read this that its the earth in the 6.0mm T&E that is coming to the shower CU..

i.e. not a separate Protective conductor?

Will a 2.5mm CPC in a 6.0mm T&E protected by a 80A or 100A fuse, be big enough for

calculation by 543.1.3 ?

As it wont be big enough for selection from table 54.7 of reg 543.1.4

page 160 -160 BGB..

S<=16 Protective conductor CSA must = S.

May need a bigger earth strapped over to the shower CU if not?

:|

 

[steptoe]

good point SL,

but that wasnt the OPs question.

 

[SPECIAL LOCATION]

good point SL,but that wasnt the OPs question.

He wants me to go back and do some other work, so just needing help on any specific regs I can show customer to prove that the shower cct needs improving.

Is not the CPC in the 6.0mm supplying the Shower CU..

also by its very nature part of the shower circuit....

that may need improving.. (if its too small?)

NO?

 

[Robin Spark]

What about the CSA of the protective conductor?Do I read this that its the earth in the 6.0mm T&E that is coming to the shower CU..

i.e. not a separate Protective conductor?

Will a 2.5mm CPC in a 6.0mm T&E protected by a 80A or 100A fuse, be big enough for

calculation by 543.1.3 ?

As it wont be big enough for selection from table 54.7 of reg 543.1.4

page 160 -160 BGB..

S<=16 Protective conductor CSA must = S.

May need a bigger earth strapped over to the shower CU if not?

:|

Can definately say without doing adiabatic calculation that 2.5mm cpc is not sufficient to cover 543.1.3.

 

[SPECIAL LOCATION]

Can definately say without doing adiabatic calculation that 2.5mm cpc is not sufficient to cover 543.1.3.

You are obviously more sober at this time of night!!!!

:slapGuinnessGuinness

 

[steptoe]

it was a bit dodgy how the 6mm was linked direct from main switch

was the fault I read posted.

nothing about earthing or supplementary earthing being provided,

I used to work with a bloke that took a 10mm earth to every shower he wired, be it in 6mmT&E or even 10mmT&E, still had a 10mm earth to it as well.

 

[SPECIAL LOCATION]

Can definately say without doing adiabatic calculation that 2.5mm cpc is not sufficient to cover 543.1.3.

When did the other spark do the original work???

Wouldn't the same CPC issue have been relevant then as well??

Even so ..

I would hazard a guess that Yellow book 130-01-01 Good workmanship would have still applied...?

Do you know what size the main fuse is?

---------- Post Auto-Merged at 00:38 ---------- Previous post was made at 00:33 ----------

was the fault I read posted.nothing about earthing or supplementary earthing being provided,

I used to work with a bloke that took a 10mm earth to every shower he wired, be it in 6mmT&E or even 10mmT&E, still had a 10mm earth to it as well.

Ah..

thats just typical of you northern blokes..

Reading the wrong bit!!! :slap

But what about if we had a live-earth short in the 6.0mm inside or just before it reaches the additional CU? ]

Its got to go up the length of the shower circuit before it reaches the additional 10mm bond at the shower? ; \

Would the 2.5mm be melted by then with a 80A supply coming to it?

 

[pkbristol]

Huh ?? Pk main cut out fuse? How would a main cut out fuse protect a6mm tande ??

Exactly my point, that fuse is too big, maybe i should have worded it better. 25mm instead of the first bit of 6mm would be better. Sorry, in my head i knew what i meant but it didn't come out right.