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Main Fuse/Power Upgrade 80amp?, 100amp?, Confused.

Jason71

Active Member
May 8, 2019
4,032
4,305
Shropshire
Thinking of having an EV charger installed and I need some advice. Although I don't know for sure I suspect I have a 60amp main fuse and 16mm tails.There is nothing written on the Fuse so don't know for sure but my house was built in the 1970s and has never had any high powered equipment except a cooker so there is no reason to think it was ever upgraded.
As I understand it I can have a charger with a 60amp fuse but it will have to be restricted to 16kw which defeats most of the purpose. So really I need it upgraded to 80amp or 100amp. If I want to get the kit upgraded as I understand it there may be several stages:

1) Network Operator is responsible for upgrading the fuse and, if necessary, the cables running into the house

2) Electricity supplier is responsible for upgrading the meter tails and, if necessary, the meter

3) "A qualified electrician will also need to upgrade your consumer tails going into your fuse board and ensure that your fuse board can also cope with a bigger fuse." This is a quote from the UKPN website.

On the UKPN website is says:"Normally we try to upgrade to 100amps free of charge for most domestic properties, we’ll need to visit you (which is free of charge) to make sure." Which is nice. Shame I am not actually in their region.
My region,Western Power,says nothing on their site. I contacted them and they were a bit difficult at first saying I needed to get my installer to fill in all kinds of forms then they would do it. I pointed out that there would be no order and hence no installer until I knew what the score was with the power and what costs there might be at which point they grudgingly admitted "We do offer an upgrade to 80amp free of charge should it be required. Once an application is made, we will probably make a site visit to establish what type of equipment you have as some cut-out where the main fuse is situated may need to be changed to accommodate 80a."

So I guess the first step would be to get Western Power in to assess what needs to be done. especially if it's not going to cost.Given I have no electric showers or other high power gear except an oven is 80amp going to be enough. Some installers like Anderson specify 100 on their site?

I currently have a dumb meter. Trying to get it upgraded to an gen2 smart meter. Is it likely I can get the meter tails upgraded at the same time as that and thus avoid having to pay my supplier anything?(currently with Peoples Energy but willing to change). Peoples Energy are only just starting Gen2 smart meter rollout so no idea when I can get a Gen2 from them. Is it worth switching to someone else to get it installed quicker maybe?

There is no form of junction between my meter and the consumer unit (which is quite new) so assume stage 3 will not apply since presumably upgrading the meter tails will have to involve a new connection all the way to the consumer unit so nothing left for an electrician to do

Any advice or insights much appreciated.
 
A few thoughts;

1. Typically home chargers are 7.2kW. In reality this equates to a 32amp fuse.
2. It's easy to get too hung up about the size of your connection. If you have light usage over night (and you intend to charge overnight) then there's absolutely no reason to upgrade a 60amp supply.
3. It is indeed the 'DNO' (UKPN/Northern PowerGrid, etc) that will analyse if you can have a larger fuse and then do that work. And yes, it's typically free.
4. Often meter tails (the cable that connects your meter to your fuseboard) will be 'split', usually with a Henely block. Although my own install uses a 32amp MCB in my regular fuseboard and has worked perfectly for a Rolec installation.

I'll post more if I get a bit more time.

Regards,

Rob
 
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MrBadger

Formerly VanillaAir_UK
Jun 17, 2019
9,297
6,893
Surrey, UK
Some installers will ask for a photo of the consumer unit/fuse box, then add all the fuse ratings together, add another 32 and work from there - this is an arse covering exercise as no way will everything be at max. Some installers may refuse to install at this point - they tried this with me until I reiterated that some was PV and immersion related.

Unless you are monitoring your power, in which case you would not be asking this, I would...

Make a note of all the circuits in fuse box and the fuse/MCB ratings.
Write down everything possibly connected to these circuits and use the power ratings from instructions/spec stickers etc - you are mostly interested in the big ones, although a room of 50W spotlights is highly noteworthy - simply because they may even be overloading an existing circuit.

Make a personal decision what you think your requirements are likely to be based on that and let the electrician know who will then use a diversity calculation (proportion of theoretical total load that is likely to be on at once). Its their number, or actual monitoring, that is the one that decisions will be based on and whether DNO are in same ball park.

At end of day, its what you have connected and use, not size of house, number of bedrooms/occupants etc.

This is a untypical day (cooking an xmas lunch for friends), but a max peak usage I have seen. Peak under 6kW, so call it 14kW if I add 7kW charger ~ 80A should be fine, 60A probably too small, I've actually got 100A. Most of this cooking, electric oven and induction - needed an uprated dedicated circuit.
intraday max.png
 
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I just had a 100amp changed from a 60amp by UKPN this morning. They also changed the tails between the fuse and the meter box. Normally they would not do that part but the guy said often after the meter company come out they have to come back as they have problems connecting to the main fuse intake. It was only about 4 inches away so said he would do it as it only took 5 minutes, nice guy. I’m now have to sort out an outside box once/if I get my model 3, that’s taking a while. I would get it upgraded as it’s free just to be safe.
 

Jason71

Active Member
May 8, 2019
4,032
4,305
Shropshire
Some installers will ask for a photo of the consumer unit/fuse box, then add all the fuse ratings together, add another 32 and work from there - this is an arse covering exercise as no way will everything be at max. Some installers may refuse to install at this point - they tried this with me until I reiterated that some was PV and immersion related.

Unless you are monitoring your power, in which case you would not be asking this, I would...

Make a note of all the circuits in fuse box and the fuse/MCB ratings.
Write down everything possibly connected to these circuits and use the power ratings from instructions/spec stickers etc - you are mostly interested in the big ones, although a room of 50W spotlights is highly noteworthy - simply because they may even be overloading an existing circuit.

Make a personal decision what you think your requirements are likely to be based on that and let the electrician know who will then use a diversity calculation (proportion of theoretical total load that is likely to be on at once). Its their number, or actual monitoring, that is the one that decisions will be based on and whether DNO are in same ball park.

At end of day, its what you have connected and use, not size of house, number of bedrooms/occupants etc.

Well I guess it would be possible to have the cooker, dishwasher, washing machine and tumble drier all on at the same time which would probably go over 60amps if you added a 32amp EV charger to it as well. Some companies (anderson) wont even allow their charger to run at the full 32amps unless you upgrade from 60amps so I thought an upgrade would be a necessity.
I do have a loop monitor and never seen the average for an hour go over 2KW but not sure what the short term peaks would be. it does not record that.
No spot lights though ,100% LED, if I put all the lights in the house on it's only about 220W total so not worried about that one
 
I've been told by PodPoint that my 60 amp fuse is fine with my 7.2kw charger. They said the charger can detect what load is on the house and throttle down if required (no idea how that works except it is something to do with a second wire going into the meter cupboard...). But my charging will mainly be at night so I can't see that being an issue.
 
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As I understand it I can have a charger with a 60amp fuse but it will have to be restricted to 16kw which defeats most of the purpose. So really I need it upgraded to 80amp or 100amp.

If it's a Model 3 you're getting remember that it's limited to 11KW regardless, it's the car's onboard AC/DC converter that's the gate. Hence it's probably more sensible and cost effective to go with a 7.2KW (32A) connection for your car.
 

MrBadger

Formerly VanillaAir_UK
Jun 17, 2019
9,297
6,893
Surrey, UK
Well I guess it would be possible to have the cooker, dishwasher, washing machine and tumble drier all on at the same time which would probably go over 60amps if you added a 32amp EV charger to it as well.

Thats where the sparkies diversification comes in. If its a standard calculation, then it should be accepted by the DNO. The problem comes when installers only use a photo, no site visit, fixed menu pricing and don't know what's connected to what.
 

WannabeOwner

Well-Known Member
Nov 2, 2015
6,720
3,493
Suffolk, UK
Worst case, if you can't upgrade the 60AMP, and have some additional high-power items installed ... or cost of upgrade is horrendous ...

... you can fit a cut-out device which will cut power to the car's WallCharger when the rest of the house circuits would take you to over-load. That would protect you against the extremely rare "all-on" of cooker, dishwasher, washing machine and tumble drier ... and also Car Charger ... and then when load dropped back down again the car would resume charging.

Cheap & Cheerful workaround would be to dial down the Charging AMPs on the car dashboard (pretty sure that is remembered based on GPS, so you would only have to do it the once, until it could be changed again)
 

Jason71

Active Member
May 8, 2019
4,032
4,305
Shropshire
If it's a Model 3 you're getting remember that it's limited to 11KW regardless, it's the car's onboard AC/DC converter that's the gate. Hence it's probably more sensible and cost effective to go with a 7.2KW (32A) connection for your car.
Oops sorry mean 16amp not 16 kw. I don't really want to be limited to 16amp. would like to use the full 32amp i,e, 7.2KW
 
I've a 60amp fuse currently and the company looking to install a Rolec charger asked me to get in touch with Western Power who 'usually' upgrade to 100amp. After getting in touch with Western Power they have advised they will only take me up to 80amps and that it'll cost me roughly £360 (£100 of that was to draw a picture of the work that needed doing).

Currently waiting on a date to have the work done and collecting the car tomorrow - just hope 3 pin charging gets me by!
 
I'm in a Western Power area, and have been going through this exact same process recently.
I've just had my charger installed today.

There are a number of things to consider...

Firstly, the cable coming into the meter box must be at least 25mm^2. Unless it is, you won't be able to have the 100A fuse.
In my case, Western Power told me that my cable was only 16mm^2, so the maximum fuse I could have would ba 80A.
If I wanted 100A, they quoted me £7,000 for the work. I pretty much laughed in their face.

The lesson to be learned from this is that Western Power don't have very good records. It really needs them to come to site, and inspect things, as when they did, my incoming cable is more than capable, and I already had a 100A fuse.

As far as meter to consumer units tails are concerned, these might not need to be upgraded if you put the charger on a separate RCD that comes straight out of the meter. As I was having my smart meter installed at the same time, the meter installer put in an isolator switch on the DNO side, so that the household could be safely disconnected without needing to involve the DNO and having new seals.

The charger was then installed with a separate RCD just for it, and henely blocks were used to attach the existing meter to consumer unit tails to the install. In this way, if the charger trips out, it won't take out the house and you don't need to upgrade your existing tails.

I can highly recommend Luke Parfitt of LAP Electrical in Honiton. He did a great job (on behalf of EcoPlugg).

Andy.
 
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WannabeOwner

Well-Known Member
Nov 2, 2015
6,720
3,493
Suffolk, UK
As far as meter to consumer units tails are concerned, these might not need to be upgraded if you put the charger on a separate RCD that comes straight out of the meter.

Mine is like that too.

I still think it needs a Sparky to advise, particularly on old wiring. If the fuse/distribution-board is old there may be some snag that will prevent EV charger cooperating.

I had Pyro wiring here (voltage rather than current trip), and some damp had got in at some point and there was some earth leakage. Not enough to trip anything ... until I added some newer RCD type consumer boxes, and then everything tripped all the time - even without an EV in the mix.

Had to have the whole house rewrired ... that was before EV even contemplated ... but I can see some people having a Right Mare over getting a Wallcharger fitted, sadly.
 

arg

Active Member
Supporting Member
Aug 22, 2012
1,838
1,853
Cambridge, UK
3) "A qualified electrician will also need to upgrade your consumer tails going into your fuse board and ensure that your fuse board can also cope with a bigger fuse." This is a quote from the UKPN website.

Doing literally that is a nightmare, as an electrician can't do that without either working live (dangerous and therefore illegal per HSAWA/EAWA) or removing the main fuse, cutting the security seal (which only the DNO or those with delegated authority like meter operators are allowed to do).
Conversely, DNO/meter operators don't permit their staff to do work on customer-owned equipment like consumer units (because they would be assuming liability for stuff that they don't have any control over). So the legal way to do it is to arrange for DNO to remove the fuse, electrician to do the work, DNO to put the fuse back - a logistical nightmare.

The more practical option is to get an isolation switch fitted between the meter and consumer unit: now you have a clear split between your equipment and the supplier's, you can turn off the switch and work on everything you own on your side of it, and they can work on their side of it.

You can usually get this fitted by your supplier (who will probably contract their meter operator to do the job), at prices varying from free to substantial. Alternatively, having one in your back pocket when having other work done (like when a smartmeter is being fitted) and asking the fitter to wire it while they are on the job is usually a cheaper option.

Note that the above applies both to the situation where you need your tails upgrading for a 100A fuse and also for the case where you are splitting the tails to have a separate consumer unit for the EV charging and leave your existing consumer unit alone - the latter again needs work on the tails which can't be done safely without shutting off the power.

-----

As to the question of whether your tails need upgrading, that depends what main fuse sizes you are talking about. 16mm² tails (most common size) are good up to 80A (if exposed on a wall), so the upgrade from 60A to 80A fuse doesn't typically need the tails upgrading; however going to 100A main fuse does.

UKPN are keen on 100A fuses, so this is most likely to be the situation if you live in a UKPN area. Other DNOs are less keen on 100A fuses, and some won't go above 80A at all (insist that you upgrade to three-phase if you want more than 80A). So experience in one area doesn't necessarily apply to others.

This is mainly a problem if you want more than one chargepoint and/or electric showers. For a single chargepoint, most ordinary households will fit within 80A, and many would be OK with 60A. For cases where it is a problem, chargepoints that can do power management with a sensor in the incoming supply are the answer - Zappi, eVolt, and EO all offer this (and probably more that I haven't noticed).
 
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Don't dismiss 16a home charging. As long as you don’t do silly miles back to back on multiple days all you need to do is charge enough to get you through the next day. Seven hours of Economy 7 charging at 16a will get you 26kWh in the battery which would probably get a Model 3 a good hundred miles.

On the odd occasion that you need to go more than 100miles you can either charge outside the E7 window, or use the charge you did get to get yourself to the nearest Supercharger.

It’s not exactly a great hardship...
 

Jason71

Active Member
May 8, 2019
4,032
4,305
Shropshire
Don't dismiss 16a home charging. As long as you don’t do silly miles back to back on multiple days all you need to do is charge enough to get you through the next day. Seven hours of Economy 7 charging at 16a will get you 26kWh in the battery which would probably get a Model 3 a good hundred miles.

On the odd occasion that you need to go more than 100miles you can either charge outside the E7 window, or use the charge you did get to get yourself to the nearest Supercharger.

It’s not exactly a great hardship...
My usage pattern will be regular journeys of 150 miles rather than lots of short journeys and even if not still seems a bit of a waste not to maximise the benefits
 

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