As long as it’s rated for 13A shouldn’t be an issue.

 

Hmm why does the manual for this plug say maximum W is 1500 bu

t
max output on the plug itself says 13A? 240x13=3.1kW.

Still trying to wrap my head around all this

 

Hmm why does the manual for this plug say maximum W is 1500 but
max output on the plug itself says 13A? 240x13=3.1kW.

Yes a bit strange that it contradicts itself. I use a simpler device like this: https://www.ebay.co.uk/itm/LCD-Powe...Electricity/223752370665?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649 which has no switching capability but simply displays the cost and usage etc on the built in screen. Been using this for a few weeks with no issues, nothing gets warm at all.

Ben

 

Its a modern way of doing things. The max value in this case, and most, is determined by the rating of the components, they can handle that current, in the short term. Long term is a different beast, thermal considerations move to the fore, and you end up with a lower value. We see the same game played with everything now, including DC car chargers/batteries!

 

1500w is about 9A @240v

 

I just had my house meters upgraded to smart meters , When charging my 24KW leaf it takes 10 hours on the granny charger , The meter shows a £0.40p per hour charge cost , So £4.00 for a charge , I get 71 miles 3 journeys to and from work for that , In my previous diesel I would get 60 mpg at £5.94 , am I happy . Oh yes and my Leaf does not have a rented battery pack

 

Heaters are a very inductive load which can cause spikes on the relay contacts. As the car has a soft start via electronics instead of a physical switch, I'd expect it to be fine. Just check after a few hours. Unplug everything and see if any pins are getting hot (slightly warm is ok, nothing more).

Regarding using the granny charger, as long as you're not using extension leads and are plugging it into a decent, modern socket on a main ring main then it's fine to run at 10A as much as you want.

 

Thanks Richard. This is exactly the kind of nuanced response I was looking for!

The flat is only a few years old, it's a new build so I suspect the socket is modern. How can I verify it's on a main ring main? I have access to the fuse box.

 

I've used the HS110 smart switch with the granny charger for over 6 months, always at full granny speed and often overnight without any signs of heating. The wifi energy monitor aspect works faultlessly. The only thing I've avoided, in the interests of switch longevity, is using the wifi app to turn ON/OFF .

 

Oh wow brilliant. Which granny charger/manufacturer is that? Switch longevity?

So did you just leave it on continuously and let the car manage power draw or switch it physically when needed?

Thanks a lot!

 

I've described the method I use for stopping charging for my e-Kona, possibly your car is different.

 

My question is whether the switch longevity issue you mentioned is still a problem if the car isn't drawing any current when you toggle ON/OFF from the smart plug app e.g. when it's stopped charging however it does.

 

You're correct. Once the current is low or zero there's no concern about the smart switch longevity

 

Thank you dave, you've been super helpful.

Yes a bit strange that it contradicts itself. I use a simpler device like this: https://www.ebay.co.uk/itm/LCD-Power-Consumption-Meter-Energy-Monitor-Calculator-Usage-Plug-In-Electricity/223752370665?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649 which has no switching capability but simply displays the cost and usage etc on the built in screen. Been using this for a few weeks with no issues, nothing gets warm at all.

Ben

Thanks for the suggestion.

As an update, I've been using the smart plug for nearly 4 hours with no issues so far.

I know that the circuit the charger is on is 32A capacity. Unless, I run the radiator (5A), kettle (13A) and microwave (5A) at the same time, I should be fine.

I do have a RCCD in the fuse box but how I do know which devices it is protecting? There's an arrow pointing towards the right where there are about 5 circuit breakers. Is it all of them? Does the RCCD have a max capacity?

Other thing I've heard being mentioned is an independent earth. Does this mean that normally everything on a single circuit/ring is connected to a single earthing point and it's worth having a independent one for high current loads?

Final consideration is this idea of 'ring faults' that @poddick mentioned. Essentially at this stage I'm just gathering information to be better informed and understand the material risk involved.

 

If you want to use a timer to control EV charging, wire it in series with the CP line on the charge plug, not the supply. This should make the car's OBC shut down cleanly with no current-carrying switch contacts opening under load

 

Whether or not the load is inductive, isn't a smartplug more likely to use a triac rather than a relay to switch the power? 40 amp triacs are cheaper and a lot smaller, plus they will prevent any need to worry about arcing. Where they may give a problem is causing distortion of the sine wave due to switching at each half-cycle of the mains. Also the smart plug will only switch the live line whilst the neutral will remain connected, although I doubt that would be a problem.

 

Whether or not the load is inductive, isn't a smartplug more likely to use a triac rather than a relay to switch the power?

The problem with triac based switches (and dimmers) is that often there is a small leakage current which means they don’t play nicely with very low current devices such as LED and CCFL lighting. It causes these devices to flicker or even just light up when ‘off’. All the smartplugs I’ve seen use a relay, presumably to avoid any complication about what type of load they might be switching.

 

A triac drops about 0.8V, so at 10 amps, that's 8 watts, which would need a pretty big heatsink for a plug-in device. a high-voltage MOSFET would probably be better, but for a consumer device, a relay may well be cheaper.