Alternative to Priority switch

The_B_Man · 18-12-2021 1:07am #1

Hi,

I had an electrician in to look at fitting an electric car charger. He said the house is wired to have the cooker and hob etc on the same fuse/RCBO or whatever so I'd need a priority switch.

I think my cooker is using a good bit of power. From what I remember, it was about 300w. I don't have an electric shower, it's a pump shower.

But anyway, from what I understand, if I'm charging the car, the whole cooker will be turned off. If I want to interrupt the charge to use the cooker, do I have to turn on/off the isolator switch or do I have to unplug the car? Coz from what I understand, the whole cooker gets shut off to the state that I'll have to set the clock every time (or actually, the clock would become useless unless I want to set it daily).

Ideally, I'd like to find a way around this so that I can at least have some power going to the cooker, and only shut off the car charger if I actually turn on the oven. I suspect the only alternative is to run a new wire to the kitchen from the fuse box, which would most likely have to go outside the house and back in.

But is there any other option that isn't crazy expensive or involves ripping walls down?

Thanks

18-12-2021 1:15am

Your cooker would be a lot more than 300W. More like about 7000 to 10000 watts at full power, and possibly even more in some kitchens.

It all depends on the size of the incoming power supply from ESB Networks. If it’s an older, smaller connection, you might not be able to operate both simultaneously.

Supplies can be upgraded, but often at considerable expense and it depends on the local infrastructure.

Ask your electrician for advice and then perhaps you could look at getting ESB N to conduct a survey for a bigger capacity connection.

It won’t require ripping down walls, rather it might require running a new feed into your house, depending on what size the incoming wires are.

It would need to be a discussion really between your electrician and ESBN.

The_B_Man · 18-12-2021 1:36am

Sorry I meant the cooker is 3000W. Or actually its 3385W. But then the induction hob is 4600W. We have the usual things like a dishwasher, washing machine and dryer, but would only use one at a time.

We got the house rewired a few years ago and got the incoming power supply upgraded. I can't remember what we got it upgraded to but I have it in my head it was about 16kW but I might just be making that number up. The house was built in the 70s, if thats any help.

I remember seeing a map of 3-phase base stations and there was one a few roads over from me, but that might be too far to get ESB to run so that's probably out of the question.

Given that the car charger will be, I think, 7.2kW then I'd say it might be pushing it to have the cooker going at the same time as charging the car. The electrician said I'd need the priority switch when he worked out all the wattage. Maybe it was a little under and he was being safe.

The car has a timer function on the charger as well, where I can set it to only start charging at midnight or whatever, but not sure I'd trust myself or herself to always make sure that setting was enabled. Maybe getting a smaller charger would be an option, eg 3.6kW but then that'd take twice as long to charge, as if I was charging from a standard plug socket. Or maybe just keeping it simple and getting an external plug socket installed might just do the job.

meercat · 18-12-2021 9:12am

If you haven’t already got a car charger,get one with load sensing built in. This prevents charging if there’s already too much power being drawn from your installation.

no need for a priority switch

I’ve never known for the need for a priority switch on a cooker circuit btw

antoinolachtnai · 18-12-2021 11:35am

There are good comments above.

if there really were a priority switch required it would make sense to wire it so that the cooker (or whatever) would have priority over the EV charger, not the other way around.

The_B_Man · 18-12-2021 11:47am

Yes the cooker would have priority, but from what I understand the power would be cut completely from the cooker as if I turned off the isolator switch. I'd have to reset the clock each time basically. And I don't know how I'd interrupt a charge if I wanted to use the cooker.

I think the charger with load sensing is the way to go. I presume you pay a premium for that? Will have a Google and see if I can find a decent one. The grant covers €600 so it'll lessen the blow to me wallet anyway.

10-10-20 · 18-12-2021 2:58pm

The cooking and car charging should - in the vast majority of cases - be mutually exclusive events as the car should be charging at night.

antoinolachtnai · 18-12-2021 7:45pm

If the cooker has priority then the car will stop charging when the oven comes on. At least in principle, the oven should always have power.

The small amount of power the clock draws shouldn’t trigger the EV to stop charging if everything is set up right. This is the same for a priority switch and a ‘smart’ charger.

But you really need to work this out with your electrician. You really need to get the electrician to take responsibility for the design of the solution

20-12-2021 12:46am

You also need to get an electrician who has familiarity with modern car chargers and isn't just doing some weird setup with priority switches and contactor relays, as if it's an old electric shower.

The_B_Man · 20-12-2021 1:34pm

https://www.boards.ie/discussion/comment/118343747#Comment_118343747

Ye, as silly as it sounds, I'd be happy with the priority switch as long as I don't have to keep setting the clock on the oven. It's a trivial concern but I know it would annoy me over the course of a number of years.

https://www.boards.ie/discussion/comment/118349662#Comment_118349662

He said he's installed some before, but you're right, he is probably thinking along the same lines as installing an electric shower. He seems good at his job though. Much better than the previous cowboy I had so rather than chancing another electrician, is there anything specific I can say to him so we're on the right track?

At the moment, I'm looking up chargers with load sensing built in. Would it be a waste to get the priority switch as well, as a backup in case the charger fails and I need to get a new one in the future without load sensing? From looking up regulations and other installs, it seems I also need an isolator switch next to the charger. Did I pick this up correctly? So from what I understand, the priority switch is a box that goes on the fuse board in the house, and the isolator goes outside next to the charger box? I'm thinking now as well that i'll get an outside 2-gang plug so I can plug in the lawnmower and have backup for the car charger (or xmas/halloween lights). I'll say this to him but I presume there'll be no complication there?

Next time he's over (probably after xmas at this stage) I'll ask him straight if he's thinking of installing the charger like an electric shower and if he's done any other installation methods. I'll also price a charger with load-sensing. My electric provider is energia and I see their cheapest charger is 1300, but it has load-sensing. Actually the 1300 includes install from their guys. I'll try find this model elsewhere.

https://smarthomestore.energia.ie/evbox-elvi-home-charging-solution

While I'm here. That charger says "Selectable 1-phase or 3-phase, 230–400V, 16 A and 32 A, 50-60 Hz".

I was doing some research on these and saw online someone said if the charger is 1-phase and your house is 2-phase, you won't get the full 7.x kW and you'll only get 3.x kW. Is that nonsense or is it something else I'll need to make sure my charger will have?

Thanks for answering the questions. I appreciate it.

Alternative to Priority switch

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