Capping off a 1 way pull cord for shower circuit

Its quite simple. The circuit can be disconnected at the consumer unit. Not a DIY job, though. It will take an electrician 15 minutes. Once completed simply unscrew the switch and dismantle. The hole can then be filled. Just leave cable in loft, or cut and remove, your choice. Edit:No you need to make the circuit completely dead. Only safe way is complete disconnection.

The old shower should have been on its own dedicated circuit. You should get an electrician in with the appropriate knowledge and testing equipment who could probably remove the supply from the consumer unit - and prove that the pull chord is not live anymore. Edit. I see you have edited your question to ask if this can be done without disconnecting from the consumer unit. You have already been given the best advice. So once again, it is best to disconnect from the consumer unit and it should be a an electrician who does it. This is not a DIY forum. Please treat electricity with the respect it deserves.

In addition to disconnection of the circuit from the consumer unit any unused circuits which are in and around cabling still in use should be connected to earth to avoid any induced voltages.

The only safe way to isolate this shower circuit is to disconnect it from its breaker inside the fuse box. Because you will have a redundant cable crrying 40 amps wondering around waiting for a accident. Do not open the fuse box yourself as there are 100 amps Live terninals inside it that you can not swith off.