Will your home electic service support a charger? - Renault Z.E. Forum
 
LinkBack Thread Tools
post #1 of 6 (permalink) Old 11-18-2012, 03:23 AM Thread Starter
Member
 
Join Date: Nov 2012
Posts: 158
Will your home electic service support a charger?

As part of my pre-purchase planning, I've been investigating connecting a wall charger to our home.

A very brief overview of the UK Power Distribution system.

National Grid owns and operates the national high voltage power transmission system. Power from the National Grid flows into regional distributors on a High Voltage network. Voltage on the HV network can be as high as 400,000 volts. The HV network connects to substations operated by Regional Distributors. From the substations, 11kV connections run to provide residential power. The network is mostly 11kV although 6.6kV is used in some locations.

Local transformers (poll mounted or buried) convert the 11kV down to 230V for domestic use.


Map of Regional Distributors:

http://www.nationalgrid.com/uk/Elect...nCompanies.htm


Each regional distributor has their own documentation on the low voltage network and residential service. I've read a few of them.

I'm going to refer to E.ON manual in the next sections.

E.ON Network Design Manual

http://www.eon-uk.com/downloads/netw...ign_manual.pdf
Andrew*Debbie is offline  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old 11-19-2012, 05:30 AM Thread Starter
Member
 
Join Date: Nov 2012
Posts: 158
Scotty, I need more power

How much total power is available to a typical UK residence?

The power cable coming into your home terminates in a cut-out box. Inside that little black box is a 80 or 100 Amp fuse. (E.On manual Page 21, last row in Table 1.2.3)

Watts = Amps * Volts: 220V * 100A = 22kW. If the house draws more than 22kW from the network, the fuse will blow.

22kW is an upper limit. What is available to charge a car is considerably lower.


There are two reasons for this. First, that 100A fuse is as a last resort to protect the LV distribution network. Design power is lower. Second, other devices in your home are consuming power.

The big power consumers in a house are electric heaters and major appliances. You can safely ignore cell phone chargers, clock radios and things like that. Combined they use maybe a few watts.

In our home the major consumers are:

Electric Shower: 7kW Electric Showers can use as much as 10kW
Hot Water Cylinder Immersion Heater 3kW * 2. For some reason, our cylinder has two of them.
Tumble Dryer 2.6kW
Clothes Washer 2.3kW (not all the time though)
Dish Washer 2.3kW
Electric Heaters 2kW * 3. (not all on at the same time)
Refrigerator ??? A+++ rated, but it might draw 2kW when cooling
Freezer
Microwave 1.6kW ????
Oven ??? Can't find spec, but about 2.5kW
Hob up to 6.6kW, but closer to 3kW in typical use.
Electric Kettle 2.2kW ????
Everything Else < 1kW

Add all of these up and it is obvious we can't have everything on at once, even with out an EV charger.








References:



Typical 100A 1 Phase power install ---

http://www.spenergynetworks.co.uk/co...se_Rev%20A.pdf
Andrew*Debbie is offline  
post #3 of 6 (permalink) Old 11-19-2012, 06:11 AM Thread Starter
Member
 
Join Date: Nov 2012
Posts: 158
I'm giving her all she's got, Captain!

I've noticed the house lights dim noticeably when our 7kW shower is on. That started me looking for design documents.

Designed load is lower than the 22kW fused maximum.

The essential design assumption is that you and your neighbours won't have everything on all at the same time.

As you add load, the voltage will drop due to losses in the network. The design spec calls for voltage regulation of about 6% of 230V.

The important part

Oil/Gas/Coal Central Heating: The design load is 12kW.
No Central Heating: The design load is 14kW.
Direct electric heaters (panels) 12kW + 50% of heat load
Storage Heaters: 4kW + Storage Heaters + Water Heater

If you don't have electric heating the main fuse is 80Amps. Maximum power is 230*80 = 18.4kW.






Want the details?
See page 22 of the E.ON manual. This section is for sizing the service cables from the transformer to a residence.
See Section 1.2.10 starting on Page 49. This section covers sizing of 11kV to 230V transformers
Google "After Diversity Maximum Demand"




Andrew*Debbie is offline  
post #4 of 6 (permalink) Old 11-19-2012, 12:04 PM Thread Starter
Member
 
Join Date: Nov 2012
Posts: 158
Does any of this matter?

If you are adding a 7kW charger, yes.

The current Generation 1 charger is 3 or 3.5kW. If you pay a little attention to other large loads that won't cause an overload.


Adding 7kW could cause problems if you don't pay attention to what else is running at the same time. In our case, taking a shower and charging at the same time is not going to work. Those two loads alone would go over the design load. Cooking dinner, running laundry and charging at the same time also may cause problems.


If you do see unacceptable voltage sags, or that main fuse blows:


Don't charge your car when other large loads are on.
Possibly upgrade your single phase service.
Upgrade to 3 phase power. Residential 100Amp 3 phase is often available in the UK.

Andrew*Debbie is offline  
post #5 of 6 (permalink) Old 11-20-2012, 03:56 AM
Junior Member
 
Join Date: Oct 2012
Posts: 47
RE: Will your home electic service support a charger?

Thanks, this is all really useful, even if some of it still goes over my head. I assumed it'd be straightforward getting a dedicated charger, but it looks like there's some research to be done. I'm thinking that if I only charge the car overnight, then the only thing in my house that's likely to be running would be our chest freezer.
Deejay is offline  
post #6 of 6 (permalink) Old 09-27-2013, 06:42 PM
Junior Member
 
Join Date: Sep 2013
Posts: 3
RE: Will your home electic service support a charger?

Possibly upgrade your single phase service.
Upgrade to 3 phase power. Residential 100Amp 3 phase is often available in the UK.

Residential 3 phase supplies are not available in the UK unless you convert to a commercial tariff. You would have to pay an unrealistic amount to get that upgrade.
Chunk is offline  
Reply

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome