The IET is carrying out some important updates between 17-30 April and all of our websites will be view only. For more information, read this Announcement

Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 52 replies
  • Subscribers 31 subscribers
  • Views 6222 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

2 electricity supplies to one building

Former Community Member
Former Community Member
Hello, I am a not an engineer but need some advice on uk wiring regulations please. 

A national utility company is fitting a 32A charger in my garage for an electric vehicle. 

The garage is detached from my house but there is an existing circuit from the house consumer unit to the garage for lighting and a power socket. The cable runs along a garden wall. 

The new charger will have its own cable run from the same consumer unit in the house down to the garage. 

My problem is that the engineer who came to do the installation refused to do it as he said the garage is a building in its own right and regulations do not allow 2 supplies to one building.

My question is: Do 2 wiring circuits from the same consumer unit constitute 2 supplies If the consumer unit is located in an adjacent building? 

I would have thought that this was still a single supply and to have 2 supplies you need 2 separate meters with 2 consumer units which is not the case here but then, as I said, I’m no engineer. 

Edit.....The engineer stated that the regulation related to avoiding the risk of a voltage between 2 different earths. To me this again only makes sense if you were talking about 2 totally different supplies from different meters and therefore possibly different sub stations etc.
Parents
  • 0
    Simon Barker:
    perspicacious:
    This doesn't necessarily mean that the supply is capable of supporting 100A, just that the individual bits of equipment can. For example a cut-out may say "100A BS 1361", but that just means the maximum fuse it can support. It may well have an 80A fuse it.


    What colour is the cut-out? Grey or black?


    Regards


    BOD


    Has the anti-EV brigade taken over this forum?


    There's no problem running an EV charger off an 80A supply.  Or a 100A supply that can only supply 100A for short periods.




    No disagreement there Simon but I think that in most domestic installations the addition of a charge point rated at 7Kw will push the MD over 60A (using standard load assessment). That being the case, the DNO must be notified PRIOR to installation. With load management, notification can be given to the DNO within 28 days AFTER the install. If you communicate with the DNO in this area, you will be lucky to get a response by next Christmas! Hence it is highly beneficial for contractors to fit load management when the just want to get the job done.

    As MapJ has pointed out this only serves the individual property. Things may get tricky for DNOs as EV uptake increases. No doubt that is what the smarts and OCPP is all about. 


Reply
  • 0
    Simon Barker:
    perspicacious:
    This doesn't necessarily mean that the supply is capable of supporting 100A, just that the individual bits of equipment can. For example a cut-out may say "100A BS 1361", but that just means the maximum fuse it can support. It may well have an 80A fuse it.


    What colour is the cut-out? Grey or black?


    Regards


    BOD


    Has the anti-EV brigade taken over this forum?


    There's no problem running an EV charger off an 80A supply.  Or a 100A supply that can only supply 100A for short periods.




    No disagreement there Simon but I think that in most domestic installations the addition of a charge point rated at 7Kw will push the MD over 60A (using standard load assessment). That being the case, the DNO must be notified PRIOR to installation. With load management, notification can be given to the DNO within 28 days AFTER the install. If you communicate with the DNO in this area, you will be lucky to get a response by next Christmas! Hence it is highly beneficial for contractors to fit load management when the just want to get the job done.

    As MapJ has pointed out this only serves the individual property. Things may get tricky for DNOs as EV uptake increases. No doubt that is what the smarts and OCPP is all about. 


Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines