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Is a 60 amp main fuse enough?
What your main fuse can carry, when it needs upgrading, and how to get it done for free.
When you add an EV charger, a battery, a heat pump or air conditioning, the first thing we look at is the main fuse: the sealed fuse next to your electricity meter. Many homes in St Albans and Hertfordshire built before the 1990s still have a 60 A fuse, some an 80 A, newer homes 100 A. An air-conditioning enquiry we had last week from AL3 had a 60 A fuse and a four-bedroom house, which is exactly the case this page is about.
How to find your main fuse size
Look at the black or grey box the meter tails come out of, usually below or beside the meter. There is often a label: 60, 80 or 100. Don’t open it; it is sealed and belongs to the network operator. If there is no label, a photo of the cut-out is enough for us to tell you. Put it in the quote form and we will check.
Is 60 A enough?
A 60 A fuse gives you about 13.8 kW in total. A normal house without electric heating rarely gets near that. The problem is what you add:
| What you are adding | Typical load | On a 60 A fuse |
|---|---|---|
| 7 kW EV charger | 32 A | Usually fine with a charger that can throttle back (load curtailment) when the house is busy. We fit these as standard. |
| Home battery with inverter | 16 to 25 A charging | Usually fine; the inverter can be limited. |
| Air conditioning, one or two rooms | 8 to 15 A | Fine. |
| Air conditioning, whole house (5+ rooms) | 25 to 40 A | Tight. Depends on what else runs at the same time. Often worth the free upgrade. |
| Air source heat pump | 15 to 30 A | Often fine, but together with an EV charger and an electric shower it is usually not. |
| Electric shower | 35 to 45 A | This is the one that pushes homes over. Two of them, or a shower plus a charger, and you need 100 A. |
We do a maximum demand calculation for every installation: what could reasonably be on at once, allowing for the fact that not everything runs at full power together. If the answer is at or under 60 A, you are fine. If not, the fuse is upgraded first, or the new equipment is set to limit itself.
Getting the main fuse upgraded
The fuse belongs to the distribution network operator (UK Power Networks for St Albans, Hertfordshire, Bedfordshire and London), not your supplier and not us. Only they can change it. The process:
- We check your meter tails and fuse board can take 100 A. If the tails are the old 16 mm² size they need replacing, which is our job (and your supplier’s for the tails on their side of the meter).
- You or we apply on the UK Power Networks website. The visit to upgrade a 30 A or 60 A fuse to 80 A or 100 A is free. They aim to contact you within 10 working days to book it.
- If your supply is looped (shared with a neighbour’s cable, common in 1930s to 1960s estates) or the cable into the house is too small, there may be a charge and a longer wait, because they have to dig.
Telling the network about chargers and heat pumps
Every EV charge point, heat pump and battery has to be registered with the network operator. If the house’s maximum demand, including the new kit, is 60 A or less, we can install first and notify within 28 days. If it is more, or the supply is looped, or the cut-out looks unsafe, we apply before installing. We handle the forms as part of the job, and it costs you nothing.
Questions we’re asked
How do I know if my main fuse is 60 amp or 100 amp?
There is usually a label on the sealed cut-out next to the meter: 60, 80 or 100. If not, send us a photo of it and we will tell you. Never open it.
Can I have an EV charger on a 60 amp main fuse?
Usually yes. A 7 kW charger draws 32 A, and modern chargers can throttle back when the rest of the house is busy. If you also have an electric shower or a heat pump, we check the sums first and may recommend the free upgrade.
Does a main fuse upgrade cost anything?
UK Power Networks upgrade a 30 A or 60 A fuse to 80 A or 100 A free of charge in most cases. You pay only if the supply is looped with a neighbour or the incoming cable needs replacing, and for any work on your side (meter tails, fuse board).
How long does a fuse upgrade take?
UK Power Networks aim to contact you within 10 working days to book a visit. The visit itself is usually under an hour. Looped supplies take longer because the cable has to be separated.
Can my electrician change the main fuse?
No. The cut-out and fuse belong to the network operator and are sealed. We prepare everything on your side and make the application; they fit the bigger fuse.
What is a looped supply?
One cable from the street feeding two houses, with the second house looped off the first. Common on older estates. The network has to unloop it before either house can have a bigger fuse, and we must apply before installing a charger or heat pump.
Written by SEGplc. Last updated 1 November 2026.
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