6491x cpc sizing

[Lee321]

anyone install 1.5 with 2.5 and 2.5 with 4.0mm etc?

seen designs with this but table 54.7!

 

[Zeespark]

Lostit, the cable circuit designs that you mention above are used completely by AMEC M+E at Heathrow and Gatwick Airports.

AndyGuinness

 

[ianmacd]

You can calculate it too. Read 543.1.2 - 543.1.4. I tend to use 1.5 with 2.5.

 

[spinlondon]

Minimum CSA should be 2.5mm

 

[ianmacd]

Minimum CSA should be 2.5mm

 

[Lee321]

spin would you put 2.5 cpc with 1.5mm circuit?

was it previously in editions gone by that table 54g? was it just said half upto certain size?

 

[spinlondon]

Wasn't aware that it was in conduit, sorry.

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, or

(ii) selected in accordance with Regulation 543.1.4.

Calculation in accordance with Regulation 543.1.3 is necessary if the choices of cross-sectioal area of line conductors

has been determined by considerations of short-circuit current and if the earth fault current is expected to be less

than the short-circuit current.

If the protective conductor:

(iii) is not an integeral part of a cable, or

(iv) is not formed by conduit, ducting or trunking, or

(v) is not contained in an enclosure formed by a wiring system,

The cross-sectional area shall be not less than 2.5mm

 

[Lee321]

you cant install singles without conduit spin

 

[spinlondon]

Sorry, I haven't explained myself very well.

If the CPC is part of a cable such as in T&E, the CSA can be less than the line conductors.

If it is installed as a separate conductor in an enclosure formed by a wiring system, such as singles in trunking or conduit then it should have the same CSA as the line conductors.

Finally, if it is run as a separate conductor not in an enclosure formed by a wiring system, such as when a CPC is added to a lighting circuit that originaly did not have a CPC then the minimum CSA is 2.5mm

 

[ianmacd]

Sorry, I haven't explained myself very well.If the CPC is part of a cable such as in T&E, the CSA can be less than the line conductors.

If it is installed as a separate conductor in an enclosure formed by a wiring system, such as singles in trunking or conduit then it should have the same CSA as the line conductors.

Finally, if it is run as a separate conductor not in an enclosure formed by a wiring system, such as when a CPC is added to a lighting circuit that originaly did not have a CPC then the minimum CSA is 2.5mm

 

[Andy™]

you cant install singles without conduit spin

if its just an earth you can

 

[Lee321]

[quote name='Andy

 

[Andy™]

correctbut we was talking about sizing in relation to a circuit

you can still install singles without conduit. look at how some factories etc have been wired!

try and tell the owners its dangerous, and all you get is 'well it works so it must be safe!'

 

[Lee321]

:^O

 

[Badger]

[quote name='Andy

 

[spinlondon]

Eh? Where do you read that from? You even posted the relevant part:

I would suggest reading all of the Regulation, not just the first couple of lines.

Specifically the last two lines:

"The cross-sectional area shall be not less than 2.5mm

 

[spinlondon]

Some people have been known to run CPCs in single for lighting circuits, that have no CPC. Other people rip out the T, and instal T&E.

Then there are those people who run supplementary bonding, in order to lower the Zs on a circuit, and even others who refuse to use the Armour of SWA as a CPC, and install a separate CPC.