Speak EV - Electric Car Forums banner

1 - 13 of 13 Posts

·
Registered
Joined
·
85 Posts
Discussion Starter #1
I'm after some electrical advice to help me charge two cars within the Octopus Go 4 hour window.

I have a ChargedEV Smart+ 7.2kW charge point fitted in my garage. The supply for it is fed from a T junction box in the meter cupboard so it's independent of the consumer unit. It'll be used to charge an e-Golf that I'll be getting when the lock down is lifted or relaxed, when the dealer re-opens.

We have ordered a Ford Kuga PHEV (which might appear in June/July - depends when the Ford plant in Germany re-opens) which is supplied with a 13 amp granny cable - it'll take around 6 hours to charge. A 3.6kW charge cable will reduce this to 3.5 hours which would fit in with the Octopus Go four hour window. I the cable will need a 16 amp commando supply.

Having researched the various types of circuit breakers, my plan is to use a spare way in the consumer unit and fit a type C 20 amp RCBO (for over load and earth leakage protection) such as 20 Amp 30mA RCBO - BG - Type C (compact) and wire it to a 16 amp commando socket with built-in isolator such as 16A 2 Pin + Earth 240V Interlocked Switched Socket IP44

Can anyone with the requisite knowledge comment on the plan? It'll all be internal to the garage. Note that I do not plan to designate the commando plug for EV charging as that would require informing the local DNO - it'll just be a 16 amp socket that I could connect any 240v appliance or extension cable to. It's a new build house and the main fuse is 80 amps. Charging will be overnight when load around the house is at its lowest.

Many thanks in advance.
 

·
I'm not crazy, the attack has begun.
Joined
·
29,849 Posts
Seems fine if the garage supply/consumer box is fully independent of your domestic consumer unit as you say. What is your doubt to ask?

Just curious then, so after the meter into the property, what does the wiring look like? You get two branches off it to two consumer units?
 

·
Registered
Joined
·
85 Posts
Discussion Starter #3
Seems fine if the garage supply/consumer box is fully independent of your domestic consumer unit as you say. What is your doubt to ask?

Just curious then, so after the meter into the property, what does the wiring look like? You get two branches off it to two consumer units?
Thanks Donald. It's a single consumer unit that supplies the entire house including the garage. The garage is integral - I realise now I missed that bit of information.

Without pictures/schematic it's as follows:

MAIN FUSE (80 amp in a 100 amp holder)
METER (100 amp)
MAIN SWITCH (100 amp)
JUNCTION BOX output #1 to 32 amp circuit for 7.2kW charge point
JUNCTION BOX output #2 to CONSUMER UNIT for ring mains, lighting circuits, oven, immersion heater, central heating.....and (hopefully) 16 amp supply to commando socket.
 

·
Registered
Joined
·
3,973 Posts
Thanks Donald. It's a single consumer unit that supplies the entire house including the garage. The garage is integral - I realise now I missed that bit of information.

Without pictures/schematic it's as follows:

MAIN FUSE (80 amp in a 100 amp holder)
METER (100 amp)
MAIN SWITCH (100 amp)
JUNCTION BOX output #1 to 32 amp circuit for 7.2kW charge point
JUNCTION BOX output #2 to CONSUMER UNIT for ring mains, lighting circuits, oven, immersion heater, central heating.....and (hopefully) 16 amp supply to commando socket.
The OP description is missing the circuit protection details, eg MCB for the charging branch #1.
 

·
Registered
Joined
·
85 Posts
Discussion Starter #5
The OP description is missing the circuit protection details, eg MCB for the charging branch #1.
'Branch #1' is protected by a MattE (instead of an earth rod) and its own small distribution board (63 amp input breaker/32 amp output breaker).

'Branch #2' has standard MCBs for the various circuits. I plan to use an RCBO for the 16 amp commando circuit for over load and safety protection.
 

·
Registered
Joined
·
3,973 Posts
Might be worth double checking that your granny charger for use with CEE socket has DC 6mA detection/switching to avoid blinding your house domestic RCDs and making them unable to protect you from ordinary domestic electric shock hazard.
 

·
Registered
Joined
·
85 Posts
Discussion Starter #7
Might be worth double checking that your granny charger for use with CEE socket has DC 6mA detection/switching to avoid blinding your house domestic RCDs and making them unable to protect you from ordinary domestic electric shock hazard.
Thanks @freddym - I need to look for a 16 amp granny cable but I'll make sure to check that is has the detection/switching you mentioned. Initially, I wanted to make sure my plan was sound before going too far.
 

·
Registered
Joined
·
4,919 Posts
Thanks @freddym - I need to look for a 16 amp granny cable but I'll make sure to check that is has the detection/switching you mentioned. Initially, I wanted to make sure my plan was sound before going too far.
As long as the RCBO for the 16A portable device (it's not really a granny, that's the 3-pin socket ones) is not fed through the house RCD DC blinding of the rest of the house won't be a problem. It might blind is own RCBO, so best to get a DC sensing one if possible, but that's all.
 

·
Registered
Joined
·
85 Posts
Discussion Starter #9
Thanks @mikegs The RCBO for the 16 amp circuit would be fed from one of the two house RCDs - here is a picture showing the two spare ways (5 and 10). Is this is a big no-no?

129659
 

·
Registered
Joined
·
7,312 Posts
Why not just fit a second 16 amp normal wall charger fed from that same 16 amp circuit that you plan to fit a commando socket to and then have to buy an expensive RCBO mobile device to plug in there?

It might mean upgrading the main fuse to 100amp but that isn't a real issue.
 

·
Registered
Joined
·
3,973 Posts
As long as the RCBO for the 16A portable device (it's not really a granny, that's the 3-pin socket ones) is not fed through the house RCD DC blinding of the rest of the house won't be a problem. It might blind is own RCBO, so best to get a DC sensing one if possible, but that's all.
I suspect based on OPs description of his system that his granny charger is going to fed through the domestic RCD in his consumer unit, whoops just seem his reply.

RCDs in series should be configured to ensue discrimination as well.
 

·
Registered
Joined
·
4,919 Posts
here is a picture showing the two spare ways (5 and 10). Is this is a big no-no?
It's not a no-no, just pointless, because
RCDs in series should be configured to ensue discrimination as well.
You already have 30mA RCDs in the circuit, so a 30ma RCBO adds nothing (except redundancy). You may as well just use a 16A MCB and save the difference.
Or you could rearrange the CU :)
 

·
Registered
Joined
·
85 Posts
Discussion Starter #13
Thanks guys. So, stick with a type B 16 amp MCB? I was thinking a 20 amp type C but again, is that overkill? Either way, get a DC sensing cable?
 
1 - 13 of 13 Posts
Top