Can I install a normal 3 pin plug where a fused spur once was, for a pool heater?

[ericmark]

So that has answered the RCD question, you have two, as to 3 pin plug instead of FCU yes as said before, good idea to disconnect the earth as well as line and neutral for equipment used outside, so loss of PEN will only present a danger when in use. Which I have also said before.

 

[Ragnar_AT]

Ideally the RCD should be replaced (it’s only a Type AC, which means it only detects AC fault currents, while current RCDs are Type A and can detect specific kinds of DC fault currents too) before you add a socket to that circuit but I‘m not sure if it’s an outright breach of the regs if you install an additional socket with AC-only protection.

The nasty bit about AC RCDs is that some things like computer power supplies can cause DC fault currents that numb an AC RCD (saturate the trip coil) and prevent it from tripping even if there was an additional AC fault.