Although solder is used for mains cables, I think the type of mains cables makes a difference. While stranded .75mm cable is usually soldered inside electrical item and such. Soldering together 2 x 2.5mm T&E cores is not advisable because of the heat. Any heat will cause the core of the cable to expand and contract and over time will force the solder away from itself, causing a dry joint, with the added tension of the cable no doubt pulling away from each other this is surely a risk or arcing, and potential fire risk.

scotch connetors

Er, no. Scotch connectors are for automotive wiring and shouldn't be used anywhere near mains cabling of any sort.

Although solder is used for mains cables, I think the type of mains cables makes a difference. While stranded .75mm cable is usually soldered inside electrical item and such. Soldering together 2 x 2.5mm T&E cores is not advisable because of the heat. Any heat will cause the core of the cable to expand and contract and over time will force the solder away from itself, causing a dry joint, with the added tension of the cable no doubt pulling away from each other this is surely a risk or arcing, and potential fire risk.

Think that about covers it.

Tell him to get someone in, or just avoid the hassle of soldering in a confined space and set fire to his house now.

Last thing you want is a dry joint on a earth connection.....

Last thing you want is a dry joint on a earth connection.....

Maybe 2nd last, the last thing would be a wet joint?