Home DIY

The boiler is close to the entry for the gas pipes (in fact I think the only gas pipes are in the kitchen where the boiler is). This is what I got from the electrician.

Install main earth bonding conductor.
It is not uncommon this conductor missing, as it was not required in older versions of the wiring regulations, or was not fitted during conversion work or re plumbing not supervised by an electrician. It's purpose is to connect together the incoming main earth with all the other conducting services entering the flat, in this case the gas, water and electricity. This will prevent any dangerous differences in voltage between pipework and electrical systems in the event of a fault. These connections are essential before any other new electrical installation can be done. Supplementary earth bonding will be fitted to the hot water and heating systems at or near the boiler if not already fitted. The new earth wire will run from the consumer unit to the boiler where it can pick up all services in one place.
The new cable will be surface wired most likely as discussed by running a cable along the staircase and hallway skirting board and then into the kitchen.