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 15 replies
  • Subscribers 31 subscribers
  • Views 10251 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

Maximum demand calculation

vantech

Hi, 

I am trying to calculate a realistic and sensible maximum demand for a project:

Ring final (kitchen) - 32A (100%) 

Socket radial 1 - 20A 

Socket radial 2 - 20A 

Socket radial 3 - 20A 

Lighting 1 - 10A (2A) 

Lighting 2 - 10A 2A) 

EV charger (with load curtailment) - 40A 

Cooker - 15.3Kw = 10A + (30%) 16.95 = 27A. 

Can anyone advise what should be applied to the socket radials? These cover sockets on the ground and first floor of the property. I have allowed 100% of the kitchen ring, but what would be appropriate for the other radial socket circuits?

I am temped to treat them all as a single 32A ring circuit, and base this on the 40% value, equalling 12.8A.

Am I also safe to allow 40% for the kitchen ring, this allowing a maximum socket outlet value of 25.6A? 

Thanks. 

 

 

Parents
  • 0

    I can see two approaches, both of which may suggest that the supply will be adequate.

    Firstly, most domestic socket outlet circuits are very lightly loaded most of the time, but a good design should allow for use of multiple portable electric heaters when the central heating breaks. In this case however an electric heat pump is proposed. That should provide sufficient heating so as not to need portable electric heaters. When it breaks, then it is NOT consuming anything, and the 28 amps that it would have used is available for perhaps three or four portable heaters.

    Secondly, consider the calculated maximum demand WITHOUT the EV charger, is it less than 100 amps ? I suspect that it is. 

    Now add the EV charger which is stated to incorporate load curtailment. Does this in fact add ANYTHING to the maximum demand ? Perhaps not, presuming that the load curtailment feature is actually fitted, works correctly, and is used.

Reply
  • 0

    I can see two approaches, both of which may suggest that the supply will be adequate.

    Firstly, most domestic socket outlet circuits are very lightly loaded most of the time, but a good design should allow for use of multiple portable electric heaters when the central heating breaks. In this case however an electric heat pump is proposed. That should provide sufficient heating so as not to need portable electric heaters. When it breaks, then it is NOT consuming anything, and the 28 amps that it would have used is available for perhaps three or four portable heaters.

    Secondly, consider the calculated maximum demand WITHOUT the EV charger, is it less than 100 amps ? I suspect that it is. 

    Now add the EV charger which is stated to incorporate load curtailment. Does this in fact add ANYTHING to the maximum demand ? Perhaps not, presuming that the load curtailment feature is actually fitted, works correctly, and is used.

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