Advice with bathroom pull cord switch

[wilk]

Hi,

Over the last few weeks the electric shower has been intermittently switching off mid shower. When I pull the cord switch off and on it comes back on again. Also I noticed that sometimes the light flickers on the shower when I switch on the pull cord as it seems quite loose.

After searching on here I found that the pull cord switches are common to becoming loose or breaking so I've had a look inside the switch. There are two 3 core cables ( earth, black and black with red sleeve ) connected to the switch. All the wires are tight however there is some what looks like heat damage to one of the wires ( black/red sleeve ).

My question is what can cause this if the wires were tight? Maybe the switch is old and worn ( It's at least 10 years old to my knowledge ) and could cause this? I'm happy to change it myself and know that I should use a good quality replacement instead of cheap rubbish but does it sound like something else could have caused the problem?

Thanks for your help in advance!

 

[securespark]

Your description sounds odd....

Pictures, please!!!

 

[JohnW2]

After searching on here I found that the pull cord switches are common to becoming loose or breaking so I've had a look inside the switch. There are two 3 core cables ( earth, black and black with red sleeve ) connected to the switch. All the wires are tight however there is some what looks like heat damage to one of the wires ( black/red sleeve ).
My question is what can cause this if the wires were tight? Maybe the switch is old and worn ( It's at least 10 years old to my knowledge ) and could cause this? I'm happy to change it myself and know that I should use a good quality replacement instead of cheap rubbish but does it sound like something else could have caused the problem?

Assuming that the cables are of adequate size for the (high) shower current, less-than-perfect connections are the usual cause of heat damage - but there are aspects of a 'perfect' connection other than terminal 'tightness'. To be honest, you'll probably never know the answer. Cables with two black-insulated conductors sound rather odd - the two black conductors are within a (probably grey or white) 'sheath', are they (rather than being 'single' conductors)?

As you say, you need to install a new (good quality) switch of adequate current-carrying capacity. You'll also need to cut back any heat-damaged cables far enough to get 'clean copper' (and hope that there's enough slack to achieve that!).

As for the adequacy of the cable for the job, do you know what size cable it is, what 'power' the shower is and what size fuse or breaker is protecting the shower circuit?

Kind Regards, John

 

[securespark]

Anyone heard of twin black before?

 

[JohnW2]

Anyone heard of twin black before?

Quite - that's why I asked whether we were perhaps talking about singles.

Kind Regards, John

 

[wilk]

Sorry guys but you were right. On closer inspection what I thought was black with a red sleeve turns out to be red but burnt and looks black towards the connector ( hang my head in shame! ). Yes, there is plenty of slack as I found it pulling more through the ceiling so it shouldn't be an issue to take it back to undamaged wire. The 3 core is encased in a grey outer altogether.

So the shower is 9.5kw. I'm not sure about the fuse but the wire looks like 6mm. Is this big enough for the shower as looking at other posts now people seem to be using 10mm?

[/img]

 

[wilk]

//media.diynot.com/220000_219142_78507_97618394_thumb.jpg

picture of said sneaky wire!

 

[JohnW2]

Sorry guys but you were right. On closer inspection what I thought was black with a red sleeve turns out to be red but burnt and looks black towards the connector ( hang my head in shame! ). Yes, there is plenty of slack as I found it pulling more through the ceiling so it shouldn't be an issue to take it back to undamaged wire. The 3 core is encased in a grey outer altogether.

Thanks for clarifying - that sounds more credible!

So the shower is 9.5kw. I'm not sure about the fuse but the wire looks like 6mm. Is this big enough for the shower as looking at other posts now people seem to be using 10mm?

If the cable isn't buried in insulation, or otherwise routed so as to attract 'de-rating factors', 6mm² cable ought to be OK for a 9.5 kW shower. Do I take it that you're sure that it is not smaller than 6mm² ?

Kind Regards, John

 

[wilk]

Sorry guys but you were right. On closer inspection what I thought was black with a red sleeve turns out to be red but burnt and looks black towards the connector ( hang my head in shame! ). Yes, there is plenty of slack as I found it pulling more through the ceiling so it shouldn't be an issue to take it back to undamaged wire. The 3 core is encased in a grey outer altogether.

Thanks for clarifying - that sounds more credible!

So the shower is 9.5kw. I'm not sure about the fuse but the wire looks like 6mm. Is this big enough for the shower as looking at other posts now people seem to be using 10mm?

If the cable isn't buried in insulation, or otherwise routed so as to attract 'de-rating factors', 6mm² cable ought to be OK for a 9.5 kW shower. Do I take it that you're sure that it is not smaller than 6mm² ?

Kind Regards, John

To be honest I'm not exactly sure it's 6mm. It's definately not 10mm but it is much bigger than the other wiring I've worked on in the house for the lights etc so it looks to be about 6mm. The shower has been fine for the last 9 years that I know of so hopefully just a case of changing the switch then. Many thanks for your advice guys. Greatly helped !

 

[JohnW2]

To be honest I'm not exactly sure it's 6mm. It's definately not 10mm but it is much bigger than the other wiring I've worked on in the house for the lights etc so it looks to be about 6mm.

4mm² cable doesn't usually look all that much bigger than 'ordinary' 2.5mm² cable (as in most sockets circuits etc.) - so, if it looks bigger than that, you're most probably right.

Kind Regards, John

 

[EFLImpudence]

the wire looks like 6mm. Is this big enough for the shower as looking at other posts now people seem to be using 10mm?

Yes.
9.5kW is 39.6A; 6mm² can carry 47A if not in conduit or thermal insulation.

Don't take any notice of needing 10mm² for the sake of it.
There is a fashion for wasting copper - and ignorance.

 

[securespark]

[Shhhhh]I have been running a 9.5 shower on 6 milli and a 40A breaker for years and it runs under some insulation.....I regularly check the terminations and the cable in the loft and it's all good.[/Shhhhh]

So yours should be fine without.

 

[EFLImpudence]

I won't tell anyone but just out of interest have you got less than four inches or more?

 

[phatboy]

I won't tell anyone but just out of interest have you got less than four inches or more?

Rather a personal question

 

[securespark]

More!!