Why does my immersion switch keep melting?

[Mk-blg]

I've had to have my immersion switch replaced 2-3 times over the last few years, the guy I had do it isn't a professional so I'm thinking he's wiring it wrong? I wired this one myself based on what way he had it wired the last time. It seems to be the blue wire that gets warm and melts everything else.

 

[DPG]

What's the deal with the short link in the Lout terminal?

 

[brianmoooore]

What's the deal with the short link in the Lout terminal?

Link is to a 2W 20A switch, that selects between two immersion heater elements.
The green/yellow used for the link looks a little undersized, so might warm things a little, and it looks like the back box might be a bit short of room, but other than that there's nothing wrong that stands out.

 

[DPG]

Link is to a 2W 20A switch, that selects between two immersion heater elements.
The green/yellow used for the link looks a little undersized, so might warm things a little, and it looks like the back box might be a bit short of room, but other than that there's nothing wrong that stands out.

Ah just saw the g/y earth colours and didn't look much further.

Usual suspects would be cheap/old accessory and/or poorly made connections.

 

[Avo Mk8]

When you rewired the last switch, you say the blue wire had overheated - was the copper a darkened/ oxidised colour?
And were other wires affected by heat?
The discolouration can give poorer surface conductivity, and the heat can make the copper softer, both of which can lead to a poorer quality termination if the overheated switch is replaced without dealing with the damaged cable ends.
It's best, if you can, to cut the wire(s) back so that you get to shiny unoxidised copper to make new joints with.
If you did this when you last changed the switch, then I would blame the switch for the problem!

 

[Mk-blg]

What's the deal with the short link in the Lout terminal?

That’s how the old one was wired so I just did the same lol. Could that be the issue?

 

[Mk-blg]

When you rewired the last switch, you say the blue wire had overheated - was the copper a darkened/ oxidised colour?
And were other wires affected by heat?
The discolouration can give poorer surface conductivity, and the heat can make the copper softer, both of which can lead to a poorer quality termination if the overheated switch is replaced without dealing with the damaged cable ends.
It's best, if you can, to cut the wire(s) back so that you get to shiny unoxidised copper to make new joints with.
If you did this when you last changed the switch, then I would blame the switch for the problem!

I didn’t cut them back as much as I probably should have. I will try that with the next switch. Thanks