One of the more common conversations we have with customers who come to us for solar panels or an EV charger is that their existing fuse board needs attention first. It’s not a given — but it’s worth understanding when it applies and what’s involved.
What a consumer unit does
The consumer unit — what most people call the fuse box — distributes the incoming electricity supply around the house and provides protection if something goes wrong. Modern units do this through MCBs (miniature circuit breakers) that trip if a circuit is overloaded, and RCDs (residual current devices) that cut power if there’s a fault to earth. RCD protection is the primary safeguard against electric shock.
When an older board becomes a problem
Older fuse boards — particularly those still using rewirable fuses rather than MCBs — don’t provide RCD protection. Under current wiring regulations (the 18th Edition of BS 7671), any new circuit added to a property should be RCD-protected.
EV chargers have a specific requirement on top of this. The regulations require that an EV charge point circuit includes protection against DC fault currents — typically a Type B RCD, or a Type A RCD combined with a DC current detection device. An older board that can’t accommodate this means the EV charger circuit can’t be correctly installed from it.
Solar installations need a dedicated connection point too. An inverter requires its own appropriately rated MCB, and in some cases the board configuration needs to handle the generation and consumption circuits in a specific way. If there’s no space, or the board doesn’t suit it, that’s another reason an upgrade may come up.
Not every older board needs replacing
Age alone isn’t the deciding factor. A consumer unit that’s relatively modern, has RCD protection, and has space for additional circuits may be perfectly fine to work with. We assess the board as part of any survey before quoting for solar or EV charger work — so you’ll know before you commit whether it needs to be factored into the cost.
What a consumer unit upgrade involves
Replacing a consumer unit typically takes the best part of a day. The supply has to be temporarily isolated while the existing circuits are transferred to the new board, protective devices are fitted, and the installation is tested and certified. You’ll receive an Electrical Installation Certificate on completion.
The cost depends on the number of circuits and the specifics of the installation, but as a general guide it typically runs between £400 and £700. If it’s being done alongside a solar or EV charger installation, there’s usually some efficiency in combining the work.
If you’re planning solar panels or an EV charger in Bristol or South Gloucestershire and aren’t sure whether your board will need attention, get in touch and we can take a look.
