Cable inside 108kW shower '4mm silicone engineering' ???

[Bmused]

Hi people,
My 10.8kW shower popped its themal cut-out, frying the closest 30mm of the main power cable attached to it, before the thing refused to play. Getting a new cut-out was easy but I've never seen any cable before like the one that was installed but is now damaged.
It has '4mm silicone engineering' printed on the soft silicone feel sheathing. The conductor is 56 strand silver colour (as apposed to copper). Cross-section looks about the same as 6mm2.
Length is 250mm running inside the plastic shower casing. It is very flexible. No-one I have found knows of it or has sensible suggestions of what I can use instead. I could bend a length from a section of 6mm 2 or 10mm 2 so it wouldfit perfectly but would std PVC insulation be ok???
Any ideas please?
Bmused!....................

 

[Spark123]

No, you shouldn't use PVC. Silicone cable is used as it is high temperature, it is more likely tinned copper conductors.
When you order then new part ask them if they can send you a new cable too.

 

[ban-all-sheds]

6mm [size=7]2[/size] or 10mm [size=7]2[/size]

FYI - you can use proper superscripts on this forum...

mm²

And if you can't get the correct spare part, contact Silicone Engineering and ask them if they can put you in touch with a supplier who sells by the m, or if they can tell you what temperature 4mm² would run at at 45A - maybe a length of 6mm² tri-rated could be substituted....

 

[Spark123]

I suspect ambient temp may play a role in its selection.

 

[ban-all-sheds]

No-one I have found knows of it

Click??

 

[ban-all-sheds]

I suspect ambient temp may play a role in its selection.

I suspect that it would contravene some law of thermodynamics for the outside surface of a copper heater can to get significantly hotter than the water inside it....

 

[Spark123]

The cable inside will be selected for its ability to withstand heat including its own heating effect. Just sticking any old type of cable in there isn't imo good enough.
The manufacturer obviously selected silicone for a reason, maybe they take into account faults with the unit? Replacing it with anything else other than the oem type or under manufacturers recommendations could be dangerous.

 

[bernardgreen]

PVC insulation will degrade rapidly due to the ambient heat inside the casing and the conducted heat along the conductors from the terminals of the element.

 

[securespark]

It is internal wiring attached to the shower unit gubbins, is it not?

In this case, spares will be available from the manufacturer.

 

[ban-all-sheds]

Good points.

And as I said - IF Bmused can't get the spare part and IF he can find out what temperature it's designed to withstand then MAYBE tri-rated cable with a larger csa could be used....

 

[Bmused]

Hi all,

Thanks for the observations and thoughts offered.
The difficulty is getting a length of silicone sheathed cable of the correct (or better) rating etc. to fabricate a replacement as no-one carries such wiring as spares.
Worse still, nowhere have I found anyone advertising silicone sheathed cable.
Rest assured I'll only be using something that exceeds OE if, as seems likely, I can't source the right part.
Totting for an old unit with reasonable wiring may be the best option!
Thanks again;
Still fairly............. bmused.

 

[jj4091]

I may be totally wrong on this one, but for only 200mm, would not a length of 10mm with a 2 or 3 layers of shrink tube fitted suffice, I would have thought that would be heat proof enough, but I am not a technical expert as far as that is concerned.

 

[ban-all-sheds]

Worse still, nowhere have I found anyone advertising silicone sheathed cable.

Widely available.

Just not by the m, which would make it a tad expensive.

I'm surprised that Silicone Engineering can't put you in touch with any wholesaler who sells it by cut lengths....

Phone & explain the problem - may they can send you a "sample"

PTFE sheathed would also be OK temperature-wise

 

[Spark123]

I may be totally wrong on this one, but for only 200mm, would not a length of 10mm with a 2 or 3 layers of shrink tube fitted suffice, I would have thought that would be heat proof enough, but I am not a technical expert as far as that is concerned.

You have to remember that it is being used inside the shower unit, the ambient temp but more likely what bernardgreen said above might have a role to play in cable selection.
I have come across silicone and fibreglass sheathed cable specced in things like theatre lights owing to their high temperatures, to put a pvc cable even with an outer sheath into a high temp environment might end up with the PVC melting / going brittle / smoking.

 

[jj4091]

I may be totally wrong on this one, but for only 200mm, would not a length of 10mm with a 2 or 3 layers of shrink tube fitted suffice, I would have thought that would be heat proof enough, but I am not a technical expert as far as that is concerned.

You have to remember that it is being used inside the shower unit, the ambient temp but more likely what bernardgreen said above might have a role to play in cable selection.
I have come across silicone and fibreglass sheathed cable specced in things like theatre lights owing to their high temperatures, to put a pvc cable even with an outer sheath into a high temp environment might end up with the PVC melting / going brittle / smoking.

If the ambient temp inside the casing was high enough to damage pvc encased in shrink tube then I think the chances are the outer case of the shower unit would melt, so that may be a slight red herring, second thoughts would suggest that an approved heat proof sleeving would be satisfactory though & probably a better idea than shrink tube, I just thought it may be more readily available.