I.T room

[spinlondon]

don't think so spinso 2.5mm singles L & N and 4mm earth

as long as VD is covered

Gonna have to ask you to explain?

 

[Lee321]

Gonna have to ask you to explain?

i don't think that the 4mm rule for expected high leakage currents applys to single earth conductor only. i.e a ring will need 4mm earth also

not only that back at the db the earths of the ring should be connected independantly

 

[spinlondon]

i don't think that the 4mm rule for expected high leakage currents applys to single earth conductor only. i.e a ring will need 4mm earth also

How does that relate to using two 2.5mm

 

[Lee321]

How does that relate to using 2X 2.5mm

 

[spinlondon]

Totally lost me there.

It was asked, if we do not require a minimum CPC of 4mm

 

[Lee321]

normally a ring would consist of 2.5 L&N and 1.5 earth but because of the high earth leakage we have to use 4mm earth but that does not mean the line conductors need to be 4mm too.

so it doesn't matter if its a ring or radial it still needs 4mm earth

 

[spinlondon]

normally a ring would consist of 2.5 L&N and 1.5 earth but because of the high earth leakage we have to use 4mm earth but that does not mean the line conductors need to be 4mm too.so it doesn't matter if its a ring or radial it still needs 4mm earth

I'm not suggesting that the line conductors need to be 4MM

 

[Zeespark]

Andy, I always thought that 4mm2 T+E has a 1.5mm2 CPC? According to AEI cables, the size of CPC in T+E is dictated by the BSI to all cable manufacturers in the UK.

AndyGuinness

 

[Andy™]

do we not require minimum 4mm cpc if leakage exceeds more than 10mA total per circuit?

yes, for a single copper protective conductor (543.7.1.3(ii))

but i was referring to 543.7.1.3(iii), which does not state 4mm

 

[musicspark]

don't think so spinso 2.5mm singles L & N and 4mm earth

as long as VD is covered

 

[musicspark]

when I read 543.7.1.3(iii) it refers me to 543

In which there is a section on high earth leakage; 543.7 I

n which there is a reference to 543

headbangheadbangheadbang

I still think 2.5mm conductors and 4mm earth is compliant.

or maybe 2.5mm or 4mm T&E with extra 2.5 single cpc

:coat

PS How can we connect cpcs independently when CU has one earth block?

 

[spinlondon]

when I read 543.7.1.3(iii) it refers me to 543 In which there is a section on high earth leakage; 543.7 I

n which there is a reference to 543

headbangheadbangheadbang

I still think 2.5mm conductors and 4mm earth is compliant.

or maybe 2.5mm or 4mm T&E with extra 2.5 single cpc

:coat

PS How can we connect cpcs independently when CU has one earth block?

Yes it is compliant.

If using two conductors as CPC, the two do not have to add up to 4mm

 

[Lee321]

when I read 543.7.1.3(iii) it refers me to 543 In which there is a section on high earth leakage; 543.7 I

n which there is a reference to 543

headbangheadbangheadbang

I still think 2.5mm conductors and 4mm earth is compliant.

or maybe 2.5mm or 4mm T&E with extra 2.5 single cpc

:coat

PS How can we connect cpcs independently when CU has one earth block?

we had to add an earth bar to db's on a job once it was carp i tell thee

 

[green-hornet]

I remember an office suite installed in the early 80,s had two 2.5 ring circuits, floor mounted not RCD, and served about 30 pc's.

Just been rewired this year, or I should say last year.

 

[musicspark]

Yes it is compliant.If using two conductors as CPC, the two do not have to add up to 4mm

 

[spinlondon]

The reference to section 543.

543.7.1.3(iii) "Two individual protective conductors, each complying with the requirements of Section 543."

"543.1.1 The cross-sectional area of every protective conductor, other than a protective bonding conductor, shall be:

(i) calculated in accordance with Regulation 543.1.3." etc.

 

[musicspark]

The reference to section 543.543.7.1.3(iii) "Two individual protective conductors, each complying with the requirements of Section 543."

"543.1.1 The cross-sectional area of every protective conductor, other than a protective bonding conductor, shall be:

(i) calculated in accordance with Regulation 543.1.3." etc.

yes but the 543.7 is the section that deals with high earth leakage not 543.1

round and round we go! Wet Fish chicken or the egg????

bad day explode

 

[ianmacd]

OK I'm really lost here. So what is wrong with a ring of 2.5mm t&e?

 

[spinlondon]

yes but the 543.7 is the section that deals with high earth leakage not 543.1round and round we go! Wet Fish chicken or the egg????

bad day explode

One of the anomolies of the Regs. I'm afraid. Probably be sorted next year with the amendment.

 

[spinlondon]

OK I'm really lost here. So what is wrong with a ring of 2.5mm t&e?

Nothing.