No, old fuse boxes are not illegal. However, if you do have an old fuse box in your property please consider health and safety. It might not be compliant with current regulations and won't have the latest RCD protection which could save your life. Consider upgrading it to a newer model....
Instead of between, could the similar circuit also be in parallel across the same diode, because on the negative half cycle of the 24VAC there's about -18V and 50mA avalible there, more than enough to power both paralleled opto circuits.Or something else... I get what he wants now. A...
demand indicators anti condensation heaters 13A RCD socket outlets, test plugs, test terminal blocks, internal lights, street lighting circuits and extension trunking / plinths. Padlocking device fitted to incoming disconnector Incoming metering Load monitoring of outgoing circuits Instrument panel ...
RCD/RCBO - Residual current devices DS200, F200, DS951 C C C x x x x x x x x Enclosures Distribution board ArTu-k x x x x x x x x x x Automation board IS2 x x x x x x x x x x Switchgear MNS x x Grounding and lighting protection ...