IET logo
 
IET
Decrease font size
Increase font size
Topic Title: EV charging and meeting BS7671
Topic Summary:
Created On: 15 July 2017 06:52 PM
Status: Read Only
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 15 July 2017 06:52 PM
User is offline View Users Profile Print this message



justinneedham

Posts: 85
Joined: 21 January 2005



As the EV population increases rapidly, there will be a demand for many more private charge points.

These typically need 32A. Also a majority of customers will want them externally mounted. (Who actually keeps a car in a garage.. Quite a small minority).
Disregarding (for the moment) UK generating capacity (A big topic on it's own), I'm coming up against two problems, immediate supply capability and earthing.

I'd be interested in what people think about these two.

Firstly, with more and more all-electric houses (and all-electric being the only way forward), there will increasingly be installers trying to accommodate an additional 32A, juggling supply diversity issues which are hard to square with customers while using the "dumb" chargers we have today. When will EV chargers have to be supplied (as standard) with not only the ability to charge/discharge in response to network-led DNO power leveling instructions, but also to use available gaps in response to the household real time current consumption?
There are already many houses (electric showers, induction hobs, heat pumps..) where the answer to "can I have an EV charger?" might need to be "No".

Secondly, I work by and large in areas where the soil is sandy and very high resistivity. I recently (before needing to give up) managed 2.5 Kohm on a 4' 5/8" earth electrode. (The second 4', which nearly killed me after an hour bashing into flinty gravel) provided about 300. On that occasion, the work needed to reach perhaps 50 Ohms Ra for an external EV charger would have been substantial, and was simply not worthwhile for the Customer. Add this to typically small driveways, lots of paving, small gardens, it's a real difficulty. Are we likely to see more "inventive" use of Risk Assessments for external EV chargers on PME systems? Is there some sort of industry plan to address this?
 15 July 2017 09:28 PM
User is offline View Users Profile Print this message



Fm

Posts: 1658
Joined: 24 August 2011

Its going to take a while to blow a 100 cut out fuse.
Earth Rods linked with with bare copper tape, with bentonite or marconite will help.
I think there was a link the other week for a SDS adapter for driving in rods, join a few together and off you go
 15 July 2017 10:05 PM
User is offline View Users Profile Print this message



justinneedham

Posts: 85
Joined: 21 January 2005

Hmm No experience of using resistivity improvers at all. . Bentonite, Marconite. How to use this stuff in "retro-fit" in limited areas? I assume to get some benefit there would need to be a reasonably wide hole, filled with it and the electrode within? I read that Bentonite is corrosive.

I did make up an SDS adaptor, but I found it ineffective. It just chattered on top of the rod, (at least with my smallish SDS). Not quite a sledge hammer.
 16 July 2017 09:44 AM
User is offline View Users Profile Print this message



jcm256

Posts: 2296
Joined: 01 April 2006

Don't forget that wealthy people who can afford an Electrical vehicle l taxi or otherwise, get a grant for a household charging unit, I as a fool cash cow tax payer will want it done right. This will cost the tax payer millions in the future, tripping hazard, fire, more ghastly wind turbines, and more power stations.


https://www.gov.uk/government/collections/plug-in-vehicle-chargepoint-grants




https://eandt.theiet.org/content/articles/2017/02/uk-needs-better-charging-network-for-electric-vehicles/

Edited: 16 July 2017 at 12:15 PM by jcm256
 16 July 2017 12:07 PM
User is offline View Users Profile Print this message



Zoomup

Posts: 3083
Joined: 20 February 2014

I read recently that the new chargers will have an inbuilt 70 Volt sensitivity Voltage operated earth leakage circuit breaker. So we won't need to worry about that aspect of the chargers.

Z.
 16 July 2017 01:29 PM
User is offline View Users Profile Print this message



alancapon

Posts: 6814
Joined: 27 December 2005

Originally posted by: justinneedham
As the EV population increases rapidly, there will be a demand for many more private charge points. . .

. . . When will EV chargers have to be supplied (as standard) with not only the ability to charge/discharge in response to network-led DNO power leveling instructions, but also to use available gaps in response to the household real time current consumption? . . .

There are two issues here. The use of the EV vehicle battery to support the grid - I can't see that happening for a long time (although I am willing to be proved wrong). It is conceivable that an incentivised tariff (cheaper than standard) may be needed for EV charging, perhaps through its own smart meter. This would then allow the charging to be restricted during periods of high use by command. This is nothing new, and can already be done with electric storage heating using the Radio Teleswitch infrastructure, where areas of the UK can be "instructed off" for a period of time.

. . . There are already many houses (electric showers, induction hobs, heat pumps..) where the answer to "can I have an EV charger?" might need to be "No". . .

It may well, and I think fairly soon three-phase supplies will be the norm in a domestic setup.

. . . I work by and large in areas where the soil is sandy and very high resistivity. I recently (before needing to give up) managed 2.5 Kohm on a 4' 5/8" earth electrode. (The second 4', which nearly killed me after an hour bashing into flinty gravel) provided about 300. On that occasion, the work needed to reach perhaps 50 Ohms Ra for an external EV charger would have been substantial . . .

That is an interesting point, which we will need to wait and see. There are some interesting proposals in the draft version of the 18th edition for EV chargers, but who knows how (of if) they will reach the final version.

Regards,

Alan.
 16 July 2017 03:14 PM
User is offline View Users Profile Print this message



MrP

Posts: 953
Joined: 24 March 2006

Just in the process wiring my house in the UK albeit been on it three months (not lost it), had a bit of 6mm left over so installed from the CU to a marshaling box at the front of the house for a car charging point for the future.
I would think the guys who undertake rewires this would be a nice little earner to sell to the customer "put it in now and its there"
MrP
 16 July 2017 10:06 PM
User is offline View Users Profile Print this message



ectophile

Posts: 728
Joined: 17 September 2001

Originally posted by: jcm256

Don't forget that wealthy people who can afford an Electrical vehicle l taxi or otherwise, get a grant for a household charging unit, I as a fool cash cow tax payer will want it done right. This will cost the tax payer millions in the future, tripping hazard, fire, more ghastly wind turbines, and more power stations.


More power stations, but fewer oil refineries. So fewer oil spills, less imported oil means better balance-of-payments for the UK economy, fewer oil tankers trundling around on our roads. Less pollution in our streets.

-------------------------
S P Barker BSc PhD IEng MIET
Statistics

New here?


See Also:



FuseTalk Standard Edition v3.2 - © 1999-2017 FuseTalk Inc. All rights reserved.

..