where to stick a rod ?

[KEVINDOE]

Hi all,

Just a quick one on a rod position, I have run a 25mm s.w.a sub-main to a holiday cottage 20 meters from an existing property that has a 3 phase supply. customer has ordered d.n.o to connect the holiday cott to one of these phases. the existing 3 phase supply is T.T.,, now , if availible, i would hope they would connect as p.m.e, but if not at wich end would you recommend the rod for the holiday cott, the supply end or the cott end ??

Thanks

 

[rocker]

I could tell you where to stick your rod, but I might get banned....

Sorry, couldn't resist. Sorry for being no help.

 

[KEVINDOE]

Or arested !!!

 

[Sintra]

Rod at supply end as this will in effect be your sub main and protect SWA with a 100mA time delayed RCD.

 

[KEVINDOE]

Thanks sintra,

if its done p.m.e, will the switchfuse be good enough protection ?

 

[Sintra]

If its done as PME then switchfuse will be fine.
You will also have to make sure that your cpc to the cottage is large enough to satisfy the requirements for your main protective bonding or you will have to make the cottage a TT anyway.

 

[KEVINDOE]

Yep, understood, its 25mm swa 3 core, am i right in saying that min would be 10mm to export p.m.e to match min size of bonding conductors??

 

[Sintra]

For a PME system the csa of the main bonding conductors must not be less than that given in Table 54.8 ie a 10mm protective bonding conductor for a neutral conductor of 35mm or less. 544.1.1
So check the size of the supply neutral.

 

[KEVINDOE]

Yes , agree, but regarding the sub-main, if the bonding conductors are 10mm csa, the the cpc of the sub-main should be at least the same?

 

[Spudnik]

The 25mm cpc would be fine, however, in this instance i would install a rod, and divorce the cottage from the main house cpc regardless.