Power and charging

[XeonSX]

Hello,

I'm about 3 months away from MS delivery but want to start looking at charger installation.
My main concern is power delivery to charger. I have a single phase power in the house and it has 100A fuse on it.
I did some calculations and my biggest consumers of electricity are as follow:
9.5kw shower 1
9.5kw shower 2
3.5kw oven
1kw washing machine
1kw microwave

Now this takes me to 98A and it doesn't include the other little things in the house. I know above are peak figures and I'm never using them all at max power at the same time but still, 7.4KW charger is another 30A.

I don't want to wait until I get the car and realise I have a problem. So, I need some advice.
Would you suggest to start thinking about 3-phase installation. Has anyone done this? How much is it likely to cost?
Or make a safe decision to only shower when car is not charging?

 

[thegruf]

Single phase charging for a new MS is max 32A, and should be plenty without resorting to 3 phase which will likely cost a ridiculous sum to install.

In reality diversity (not everything using max power at the same time) will mostly manage your load.

You can, however, limit the max charge rate if you wish to from the phone app or the car.
You can also schedule charging so eg it charges overnight when other power usage is reduced.

Further still your 100A incoming fuse will actually withstand quite a bit over that for a limited time (eg boiling a kettle taking it over the limit)

In other words don't panic, all will be okay. And even if you existing usage is high there's plenty of ways to manage it.

Last but not least - you can imagine a forum like this would be riddled with scare stories about how their Tesla had taken out their house supply, all the food had gone bad in the freezer, the children had been taken into care, their wife had left them because her hair straighteners didnt work in the morning, you know all that excitement you get on forums.

Just sit back and count the sleeps until your new baby is delivered.
You won't be disappointed.

 

[cantanko]

My sparky has rigged some contactors for his other clients. He had an economy-7 customer with a 60 amp feed and a 7kw shower. Contactor is timed to inhibit the shower during the E7 window, and inhibit the car charger at other times. It obviously had a manual override, too, but I thought it was a neat solution to limited available power...

 

[miimura]

I recall seeing a UK based company offering a home charging point that would monitor the incoming service line and when it neared capacity, it would automatically signal the car to reduce its charging so the total house draw would remain within the main fuse rating. I'm sorry I don't recall the name of the product or company.

 

[thegruf]

I recall seeing a UK based company offering a home charging point that would monitor the incoming service line and when it neared capacity, it would automatically signal the car to reduce its charging so the total house draw would remain within the main fuse rating. I'm sorry I don't recall the name of the product or company.

this actually must be the future of charging.

The next generation of chargers must be able to balance their charge vs available power, measured as incoming limit minus other load, but also must be able to talk to other chargers on the same spur from the local substation to manage diversity on the supply cable too, level up from this to manage the overall load on the substation step down transformer too.

It's all coming, there will be lots on panic. hyperbole and FUD but actually will work well.

Beyond this Elon will have the cars drive away autonomously to a local smart charging lot, then you can just summmon them back again when you need them, thereby freeing up the garage for the endless junk, the autonomous lawnmower and elderly relatives

 

[DJP31]

I have a 1930's built house and pretty sure the original main fuse, whatever that might be.

At 6AM using E7 and because it's the morning I am highly likely to have the car charging via the Tesla wall charger, washing machine, tumble dryer, power shower, kettle, hob and hair dryer all on the go at the same time. That's living with a wife and 2 adult daughters for you!

Never had a problem with any of the appliances, can't say the same for the occupants though!

 

[thegruf]

... probably got a nail for a fuse

wife and two daughters = 3x hairdyers always used simultaneously btw

 

[arg]

I recall seeing a UK based company offering a home charging point that would monitor the incoming service line and when it neared capacity, it would automatically signal the car to reduce its charging so the total house draw would remain within the main fuse rating. I'm sorry I don't recall the name of the product or company.

The eVolt unit, as advertised here?


Or you can fit something like this - intended to interlock two showers so they can't be used at the same time; could equally be used to interlock shower vs EV charger.

 

[WannabeOwner]

Knock on wood but ...

... we have a large house, lots of electrical stuff, seriously under-sized (aged ...) cable underground for 100 yards to pole, and 100 AMP fuse; we have E7, most white goods are set for overnight timer, car charging too. Never had a problem - had expected some brown-outs but not seen that either.

 

[arg]

most white goods...

The thing with white goods, cooking appliances, indeed almost all sorts of appliances in a house is that the energy ultimately turns to heat. So you don't need to do complex analysis to conclude these things can't in practice run at sustained high power in any modern at-least-moderately insulated home: if they did, the place would soon turn into a sauna. Obviously you can get a short-term high current if you turn them all on at once, but generally it's the sustained load that is of concern and most of these devices will only be drawing full power for short periods.

The one exception among the things listed by the OP is his two electric showers: these do have a way of getting rid of large amounts of energy indefinitely - they pour it down the drain (literally) - and you could reasonably imagine them being used for 20 minutes at a time which is long enough to be significant in terms of blowing fuses.

So I wouldn't normally consider a 3-phase upgrade to be warranted unless the house is already very large and/or is using electricity for heating. However, interlocking the EV charging with the shower(s) may be necessary. Of course, you may regard a larger-than-strictly-necessary power supply to be a luxury that you can afford and will enjoy more than, say, a set of 21" wheels - if so, why not go for it?

 

[XeonSX]

Thanks everyone for replies, much appreciated. I will try to be sensible and go for single phase 7.4KW charger that will hopefully only run from midnight when there's little chance of multiple showers running.