Exporting final circuits

The Local Authority I work for as an Electrical Engineer is developing low carbon three story flatted residential properties with six flats in each block.

Each flat has its own single phase supply and there is 3-phase landlord's supply covering the common areas

The Mechanical Consultant has specified Air Source Heat Pumps as heating and hot water solution which is fine.

I am not at ease with the arrangement of the equipment the indoor unit is in the flat which is OK but the outdoor unt rather than being mounted on a balcony or wall of the flat it serves is located in separate out building.

This does not seem right as I have export a final circuit from the tenants consumer unit out with the boundary of their property through the common area then right outside the building to an out building.

Also the out building accommodate six final circuits all from different metered installations and also circuits from the landlords supply.

This seem highly irregular to me as all the guidance I have looked at for installed ASHP's states that in a flatted properties that ASHP's should either be a individual systems installed in the flats or a central system in which case it would be on common ground and be fed from the landlords supply.

Does anyone know of any regulations that advises against or prohibits final circuits from different DNO metered installation being mixed in the soom area / room? I have also asked this question to the DNO

Any feed back will be appreciated

Thanks

Alan Gray

Parents
  • I understand your concerns - the arrangement certainly fails on the 'least astonishment' principle. But having multiple supplies in the same area isn't unknown in the broader sense - in many critical situations (e.g. life support or data critical systems) it's very usual to have duplicated independent supplies (some with UPSs that stay hazardous live even when every upstream isolator is fully open), so there's not going to be any fundamental regulation to simply prohibit this sort of thing in principle. Going back a few years it was common to have off-peak storage heaters on a completely different DNO supply within a home (well same cut-out but separate metering and separate CUs and everything else downstream) and people got used to that. So it's really down to being clear about what goes where (and is fed from what) - so lots of clear labelling and things like tidy distinct cable runs and general layout could help too.

        - Andy.

  • Thanks for your replay and yes places like hospitals have NPS, EPS and UPS supplies and a domestic dwelling can have an off peak supply but even in these circumstances the final circuits remain within the boundary of the customers property, I the situation I am describing final circuits are leaving the customers property and going into common areas.

  • I the situation I am describing final circuits are leaving the customers property and going into common areas.

    How would you feel about a parking space (for 2 cars) between two adjacent properties with 2 adjacent EVCPs?

  • Normally EVCP including a vehicle which may be plugged into it must be at least 2.5M from any other supply or extraneous metal work bonded to a LV PME, would that include another EVCP fed from another supply I would think so, I believe if the EVCP is supplied by from an O-PEN device it helps with the proximity of 3rd party supplies.

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  • Normally EVCP including a vehicle which may be plugged into it must be at least 2.5M from any other supply or extraneous metal work bonded to a LV PME, would that include another EVCP fed from another supply I would think so, I believe if the EVCP is supplied by from an O-PEN device it helps with the proximity of 3rd party supplies.

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  • would that include another EVCP fed from another supply I would think so

    That depends on whether the other supply has the same earthing system - so two EV's fed from two different buildings supplied from the same TN-S private network on a large site might be OK, but two vehicles fed from two independent electrical installations with separate supplies perhaps not.

    The relevant Regulation to consider is 411.3.1.1 (particularly 2nd paragraph)

  • OK, if you have a parking space between two buildings and the EVCPs are on the sides of the houses, they might be 5.0 m apart. On the face of it, that is compliant, but what is the situation when both neighbours have their EVs plugged in?

    Leaving aside the question of "why would you?", of greater concern is that the cables could be unwound and one plug held in each hand.

    This is the situation which recently cropped up here.

  • EVCPs are on the sides of the houses, they might be 5.0 m apart.

    The IET CoP recommends the "simultaneous contact assessment" is done with respect to the EV not the charging point.

    You can, from there, reach your own conclusions ... All I could say at this point is that, per Reg 411.3.1.1, ADS requirements would not be met ... so an alternative means of protection against electric shock (to ADS) is the only option.