UK 3 Phase PME to domestic building?

[deckie]

Good evening all.. I have recently installed a new 100amp 3 phase supply for a domestic premises with outhouses. The incoming 100 amp supply is PME and approx 30 metres from the main dwelling, a new metering cupboard was built for the new head and meter. I installed a small sub board and two 100amp switched fused isolators.

No 1: Switched fused isolators are feeding SWA submains supplying two parts of the main property
No 2: MCB's supplying small wooden out houses/sheds

Question I guess.... Should I have made the five outgoing SWA supplies TT's and supplied an earth spike at each distribution board, and RCD protection on each outgoing submains or just PME it?

The original supply going into the main house was PME 100amp single phase, none of the outgoing supplies to any of the out houses where TT, just SWA with exported earth.

 

[westward10]

If main protective bonding is required then the armour must be of adequate csa to support it. If if it is not then a separate conductor should have been installed.

 

[thomaspotato]

single core copper 16mm (assuming mains are 25mm) ran with swa would be good but additional earth spike alongside the armour should be fine. Whats the zs at each sub board?
[automerge]1571175840[/automerge]

single core copper 16mm (assuming mains are 25mm) ran with swa would be good but additional earth spike alongside the armour should be fine. Whats the zs at each sub board?

Spike might not be necessary if good earth fault loop impedance or mccb

 

[deckie]

If main protective bonding is required then the armour must be of adequate csa to support it. If if it is not then a separate conductor should have been installed.

If main protective bonding is required then the armour must be of adequate csa to support it. If if it is not then a separate conductor should have been installed.

Hi westward
the csa of swa are ok , used 4 core 16mm doubled up on cores protected with 60 amp hrc fuse,swa outer sheath should be sufficent once properly glanded and earth fly leaded ?
The out houses are all run with outer sheath and inner core earths
was suddenly wondering if i had needed to run sll sub mains as TTs

 

[fairlight]

The steel armouring will not be deemed adequate for protective bonding. Are there any extraneous incoming services that require main bonding in the buildings served by the distribution circuits? If so if you can ditch the doubled up cores and use one as a copper cpc (minimum 10mm) that will be adequate to meet main bonding back to the MET, but may no longer be adequate to meet volt drop requirements on the live cores. If you cannot get at least a 10mm copper from the MET to an outbuilding with bonding requirements then you will have to either TT or use the SWA as you are now and sign it off as a departure on your EIC.