Immersion Heater Wire Changing Colour

[Shythorn]

Hi,
I need some advice please.
Last year I bought some grey H05BN4-F cable for my immersion heater.
It is 24"/61cm from my wall switch to the timer and 29"/74cm to a toolless Junction Box rated 24A. This connects to the immersion heater wire, I can't change this wire. The heater and wire look like the original ones that came with the house when it was built, 1966-1967.

The problem I have is the grey wire is changing colour, it's looking beige in different sections.

I take it the cable is failing :-/

 

[GBDamo]

Hi,
I need some advice please.
Last year I bought some grey H05BN4-F cable for my immersion heater.
It is 24"/61cm from my wall switch to the timer and 29"/74cm to a toolless Junction Box rated 24A. This connects to the immersion heater wire, I can't change this wire. The heater and wire look like the original ones that came with the house when it was built, 1966-1967.

The problem I have is the grey wire is changing colour, it's looking beige in different sections.

I take it the cable is failing :-/

View attachment 49594

View attachment 49595

Unless its in direct sunlight its probably heat related.

Cold be a loose connection, incorrect size coductors or, believe it or not, fake cable.

What size are the cores in the cable?

I use 3093Y 1.5mm or 2.5mm depending.

 

[Shythorn]

I thought about fake cable, as I bought it from ebay. Plus if you look up the code and find the specs, they say the insulation colour is white or black. Not grey.
I'll go to screwfix and get 3093Y 2.5mm to be on the save side.
Thanks

 

[GBDamo]

I thought about fake cable, as I bought it from ebay. Plus if you look up the code and find the specs, they say the insulation colour is white or black. Not grey.
I'll go to screwfix and get 3093Y 2.5mm to be on the save side.
Thanks

You've managed this once without killing yourself so I'll not insult your intelligence by saying make sure your safely isolated, although I kind of just did.

Just make sure you use bootlace ferrules on the cables ends.

Quite a common failure is burnt out terminals and cables due to stranded cables splaying and giving poor connections=risistance=heat.

 

[ruston]

Also check the old wiring , 50 + years on an immersion heater is a long time . Check the connections of the stat at the top of your tank , it is a weak spot for high resistance . Also ; as said check all your control connections .

 

[suffolkspark]

Heck not seen that before, 1.5mm heat flex or butyl flex will see you fine, just go and grab it from an electrical wholesaler, as above ensure you use ferrules on screw terminals or tin the ends

 

[ruston]

Heck not seen that before, 1.5mm heat flex or butyl flex will see you fine, just go and grab it from an electrical wholesaler, as above ensure you use ferrules on screw terminals or tin the ends

Yes , Butyl is a good as you will get. The heat resistant stuff most wholesalers sell now doesn't.

 

[Charlie_]

I asked for butyl at the wholesalers on Friday, lad didn’t know what I was talking about.. He’s still learning though.
So many different terms for all sorts of products

 

[Wilko]

Hi - my bet is the discoloured cable has 1mm conductors. Not man enough for the job really.

If you use the immersion as your main heating for HW and it’s very old you might want to get the whole thing upgraded to include the extra thermal cutout and replace the cable end to end.

 

[davesparks]

I've seen that before with cheap white rubber cable, we had a drum of it when I was an apprentice and the cable went like that whilst still on the drum.
No idea why it happened, we just chucked it in a skip.

 

[Charlie_]

Whilst on the subject of cable anomalies;
Does modern day pvc cable still react with polystyrene?

 

[westward10]

Never say never but it shouldn't do. The plasticiser used in cables years ago to make them more flexible was replaced by urethane based products which doesn't as far as we know migrate from the pvc like the old plasticiser products did when in close proximity to certain materials.

 

[Charlie_]

Took some older rb cable out recently which had been ran behind insulated board, it had migrated quite badly.

 

[westward10]

Rubber cables deteriorate due to age from exposure to sunlight and temperature increases. Unlike pvc no chemical migration takes place it just ages as the oils dry from the rubber material a process encouraged by sunlight and temperature increases.

 

[Bobster]

Never say never but it shouldn't do. The plasticiser used in cables years ago to make them more flexible was replaced by urethane based products which doesn't as far as we know migrate from the pvc like the old plasticiser products did when in close proximity to certain materials.

Green goo!

 

[Charlie_]

Green goo!

Job from a couple of weeks ago

 

[Shythorn]

Hi all, here is an update.
I've changed the cable to 3093Y and used bootlace ferrules on the ends.
This is what the old cable looks like:

 

[Toneyz]

What size flex is it? as it looks like it is overheating (too small flex c.s.a.) watch John Ward's video's the minimum spec for an immersion heater flex is 1.5 heat resistant three core flex.

 

[Charlie_]

Just flicking through the osg and it states that p.v.c. sheathed cables must be separated from polystyrene.
So what do you think, still relevant or osg is not up to speed with new cables?

 

[Deleted member 26818]

The OSG also tells us Cooker switches must be within 2m of the Cooker.
Can’t remember if that was dropped from the Regs in 1966 or 1981.