New Consumer Unit Needed For 100 Amp Main Fuse

Hi, this could be needed with the EV CHARGER. Pulling around 32a i done. Kettle test in my house using a clamp meter 3 bed semi detached house with everything on was coming out at about 75amps you should always take diversity into effect knowing that everything’s not going to be on at once but yes i would suggest a new consumer unit with a 100 amp main switch with surge protection to protect your new electric car from any voltage surges. You have to be careful with RCD selection aswell most car chargers should have a A TYPE RCD as a or rcbo as the normal AC TYPE rcd can get confused I’d advise a rcbo board with a A type rcbo for the car charger for better selectivity .

Hi Thomas, So MK Sentry manufacture stopped in 2019 and replacement parts are likely going to be an issue going into the future. To figure out if you need a new board you will need to know a few info points: 1: do you have space in your current board for new circuits ? 2: is there available parts such as type-A rcd's & mcb's or rcbo's available for that board ? 3: are the main tails rated for the full 100amps i.e. 25mm tails or are they the old 16mm ones ? 4: what earthing system is present at the property as this will effect the type of car charging setup you will need ? There are multiple things you would need to know to answer that question properly. With the limited info available it sounds like a new larger consumer unit with likely new tails would be your best option. I hope that helps.

Hi Thomas, Without seeing you consumer unit, it is difficult to confirm whether it requires a replacement. I suspect from the BSEN number, that it is a fairly recent unit within say, the last 20 years. Does it have two RCD's splitting the circuits or just one protecting the whole installation? If it does have two, then it is likely that one will be rated at 63A and the other at 80A. There is no need to replace the unit if this is the case, unless it has holes or damage to it that fingers can get into. The car charger will need to be fitted to the 80A side. If your board has just one RCD, then it would be prudent to look at replacing it as it won't comply with the current regulations. Go for a larger one than what you think you would need as this would future proof for your needs. You could also go for an additional smaller unit which would mean splitting the meter tails through what is called a Henley junction terminal, but this would not solve your long term requirements. Whichever way you go, ask your installer of the charger not to connect the main earth to your circuit, they will need to install a spike outside for the earth to the charger.

Install a consumer unit dedicated to the EV charger.

Odd advice from the DNO. The type of consumer unit fitted has nothing whatsoever to do with the rating of the cut-out fuse. The 100A one they are putting in for you is just a precaution against possible overload. They don't want to be called out to replace the 63A one every time you use the car charger! Let the car charger installer advise you. Some EV chargers already have built in safety devices and only need an upstream mcb.