EV charger and other appliances

[zoolander]

We have a MG EV car.

To charge this at home we have a dedicated electric meter and consumer unit where the charger is fed from .

The meter is a Tou meter.

We have several spare ways on the consumer unit and was thinking we could move the washing machine from our house electric supply to the EV charger  supply.

Will this be ok or will it impact in charging the EV.

 

[Crossy]

It will have no effect upon your EV charging.

 

I'd go for it and get cheap power for your washer.

 

 

[sometimewoodworker]

Just be absolutely sure that you use the Power during the cheap period, as the daytime power is about 25% more expensive than the most expensive normal power

[MJCM]

Just FYI the TOU Peak and Off-Peak times

 

Quote

 

Peak

09:00 a.m. - 10:00 p.m.
Monday-Friday

 

Off - Peak : 10:00 p.m. - 09:00 a.m.

Monday-Friday and Royal Ploughing Ceremony Day
00:00 a.m. - 11:59 p.m. (24 hrs) Saturday - Sunday, Labor Day,
The Royal Ploughing Ceremony Day which is on Saturday or Sunday,
Public Holiday (except Compensatory Holiday)

 

So it would be safe to say if you do your washing and charge your car at Night then you will be using the off-peak rate

 

https://www.pea.co.th/en/electricity-tariffs

[MJCM]

@Crossy

 

Is the TOU meter usually a 30/100 or .... ?

[Crossy]

11 minutes ago, MJCM said:

Is the TOU meter usually a 30/100 or .... ?

 

IIRC PEA are offering a 15/45 supply for the EV charger.

 

That said, the electronic meters are all 5/100 rated and effectively "universal".

 

[digbeth]

if one were to wire the house aircon to the EV TOU meter with a crossover switch for cheap rate at night, do you have to be careful with the grounding in case the TOU meter were taken of different phase wire of the pole? 

[Crossy]

Just now, digbeth said:

if one were to wire the house aircon to the EV TOU meter with a crossover switch for cheap rate at night, do you have to be careful with the grounding in case the TOU meter were taken of different phase wire of the pole? 

 

No problem with grounding, all your grounds are referenced to the common neutral in a TNC-S system.

 

Oddly enough I was thinking along exactly those lines. One could adapt the ESP8266 internet timer that I'm using to control the export system on our solar to operate the transfer switch. Give it a calendar file as well and it could set up for holidays as well as weekends.

[digbeth]

21 minutes ago, Crossy said:

 

No problem with grounding, all your grounds are referenced to the common neutral in a TNC-S system.

 

Oddly enough I was thinking along exactly those lines. One could adapt the ESP8266 internet timer that I'm using to control the export system on our solar to operate the transfer switch. Give it a calendar file as well and it could set up for holidays as well as weekends.

I wonder if enough people are doing this, would PEA disallow 2nd meter to be TOU while the main one is normal rate or if they have a clause when signing up that the TOU meter is for EV charging only

 

MEA in Bangkok will only let you have 2nd meter if you switch the whole house over to TOU

 

 It's probably the same as exporting from Solar, as long as they don't see you doing it it's probably fine

[MJCM]

1 hour ago, digbeth said:

MEA in Bangkok will only let you have 2nd meter if you switch the whole house over to TOU

That s........ ????

 

@zoolander

 

Question please.

 

Do you now have 2 Electricity Meters?

 

Meter 1 normal Disc Meter for the House

Meter 2 a Digital Meter for the TOU / EV?

[sometimewoodworker]

1 hour ago, Crossy said:

No problem with grounding, all your grounds are referenced to the common neutral in a TNC-S system.

Are you sure of the grounding and supply situation?

 

As I understand there are rather special requirements for an EV charging station and you can manage to have your vehicle live at mains potential if you don’t get things absolutely correct. 
 

it also seems that an EV station may need to be TT not TNC-S for safety 

 

That could be a bit of a shocking experience ???? 

 

 

 

 

Edited December 7, 2022 by sometimewoodworker

[Crossy]

1 hour ago, sometimewoodworker said:

As I understand there are rather special requirements for an EV charging station and you can manage to have your vehicle live at mains potential if you don’t get things absolutely correct. 
 

it also seems that an EV station may need to be TT not TNC-S for safety 

 

Yes, but that's the actual station NOT the CU it's fed from!

 

You need Type-B RCDs too for proper protection.

 

The installation instructions for the EVSE should have all the relevant detail.

[digbeth]

2 hours ago, digbeth said:

MEA in Bangkok will only let you have 2nd meter if you switch the whole house over to TOU

to clarify, they'll also let you have 2nd meter with normal non-tou rate the same with the house, but the catch is that they have to be both on the same plan, so the 2nd meter is only good for case where you don't want to touch or rewire the existing house connection when they come to inspect it, so just run another meter from the pole to the charger and put it on the same account

 

whereas PEA will let you have the 2nd meter be TOU while the main house on standard tariff, best of both world.

 

The 2nd meter for just EV is probably for case where the existing meter is too small, if you already has 30(100)A meter and good wiring, just run the wire from the consumer unit to the charger, For people with smaller meter or older house, getting a separate meter is probably easier than to rewire the house to pass inspection in order to get upgraded meter, 

[Crossy]

I did post the installation instructions for the BYD Good-Cat charger, but of course now I can't find them on AseanNow or the BYD website ???? 

 

[zoolander]

1 hour ago, MJCM said:

That s........ ????

 

@zoolander

 

Question please.

 

Do you now have 2 Electricity Meters?

 

Meter 1 normal Disc Meter for the House

Meter 2 a Digital Meter for the TOU / EV?

Yes, 2 meters. Old disc one for the house. New digital one for the EV 

[zoolander]

4 hours ago, Crossy said:

 

No problem with grounding, all your grounds are referenced to the common neutral in a TNC-S system.

 

Oddly enough I was thinking along exactly those lines. One could adapt the ESP8266 internet timer that I'm using to control the export system on our solar to operate the transfer switch. Give it a calendar file as well and it could set up for holidays as well as weekends.

So could I use a single pole transfer switch for the live wire to the air conditioning. Or is it best to try to locate and switch the neutral too...

[JBChiangRai]

At my house I have lots of solar with a weak PEA supply, so I tend to charge one sunny days only.

 

At the house in Chiang Mai I bought for my two daughters at university there for the next 3.5 years, we have 30/100amp meter and I fitted a 3rd party charger,

 

I have considered getting a 2nd TOU meter and using a couple of programmable 63amp Sonoff contactors, switching the entire house over to the TOU meter at 10pm and disconnecting the normal meter 1 minute later and vice-versa in the morning, i.e. achieving make-before-break, not only would charging be cheaper but their 2 air conditioners in their bedrooms, refrigerator etc would be cheaper overnight too and we'd still get the standard rate during the day.  I am not sure I would get an ROI over 3.5 years though.

[Gweiloman]

14 hours ago, zoolander said:

Yes, 2 meters. Old disc one for the house. New digital one for the EV 

Did you have to pay for the 2nd meter and if so, how much? Also, how long did it take PEA to install it?

[zoolander]

42 minutes ago, Gweiloman said:

Did you have to pay for the 2nd meter and if so, how much? Also, how long did it take PEA to install it?

2nd meter about B4500 three weeks to fit from order. Udon Thani office 

[Crossy]

1 hour ago, JBChiangRai said:

and disconnecting the normal meter 1 minute later and vice-versa in the morning, i.e. achieving make-before-break,

 

Warning Will Robinson! Warning!!

 

Be very careful.

 

If your meters are not on the same phase some pretty major bangs will result. Even if they are on the same phase NOW it's always possible that PEA will come along and move one of them to a different phase to balance their load.

 

Break-before-make every time when switching supplies.

 

EDIT I would also use electrically and mechanically interlocked contactors, have a look at my 3-way transfer switch thread for examples and source.

 

 

[JBChiangRai]

For sure, make-before-break only if on the same phase

[Crossy]

17 minutes ago, JBChiangRai said:

For sure, make-before-break only if on the same phase

 

It is of course entirely up to you, but IMHO the risk of accidentally connecting two phases together via your transfer arrangements is really too great. You have no control over what and when PEA do any work in the street.

 

The resulting bang isn't going to be small. In fact, it will be potentially explosive, leading to the destruction of your contactors and very possibly your meters.

 

I've not actually measured it, but the transfer using our interlocked contactors is sufficiently fast that none of our kit objects, there's barely a flicker of the lights.

[JBChiangRai]

11 minutes ago, Crossy said:

 

It is of course entirely up to you, but IMHO the risk of accidentally connecting two phases together via your transfer arrangements is really too great. You have no control over what and when PEA do any work in the street.

 

The resulting bang isn't going to be small. In fact, it will be potentially explosive, leading to the destruction of your contactors and very possibly your meters.

 

I've not actually measured it, but the transfer using our interlocked contactors is sufficiently fast that none of our kit objects, there's barely a flicker of the lights.

Yes, you are right, PEA could change something without my knowledge, could you share a wiring diagram for your interlocked contactor setup?

[Crossy]

1 minute ago, JBChiangRai said:

Yes, you are right, PEA could change something without my knowledge, could you share a wiring diagram for your interlocked contactor setup?

 

You need to do something like this, contactors are shown in the earlier linked thread.

 

[JBChiangRai]

Actually, on reflection, I could just use a double pole changeover contactor, I don't think there is anything in my daughter's house that would object to the absence of power whilst the contactor changes over, and I would use a Sonoff device to operate the coil, that way it's RTC would be synced to the internet.