Shower terminals

[shaggy]

This is a Triton shower which has been in use for about 7 years. The wire that has failed is connected to the thermal cut-out on the water outlet. The top connection has not failed so I'm thinking that it was the actual push-on connector not making a good contact. I've just replaced the unit but the connections are the same and I can wriggle them side to side so I'm not convinced about them.
I'm familiar with these connectors on car electrics but does anyone know the rating of them? Also the insulation has melted so is this capable of catching fire or does it just carry on melting?

 

[andy]

if will catch fire

 

[Damocles]

Well, it didn't. it just failed.

It is very hard to tell from your picture which connection actually failed, whether it was the switch, the push on clip or the weld between clip and wire.

 

[plugwash]

it looks like lukilly for you the heat (presumablly from a bad joint) broke the joint before the heat burnt anything really nasty

 

[shaggy]

I think it was lucky it failed as well, sort of like a fused link. I've just cut the overheat switch open and it operates by the base of the switch in contact with the water expanding and pushing a plastic plunger which separates 2 contacts. These don't show any sign of overheating so I think the problem was the connection at the wire. The joint is a mechanical crimp which still looks sound but the wire has failed as it leaves the crimp. I think the heat was generated by not having a very good contact between the push-on female and the spade.
It shows that despite the correct size cable, correct mcb, correct shower switch and rcd protection there is still room for problems from manufacturing defects.
I've had some good service from Triton showers, and they give a good spares service, so I'm not calling them rubbish but I think I will ask their opinion.

 

[Adam_151]

We have an old shower kept for spares (thing it may have come from a carboot sale), that has the same connection burnt out in the same way (but all the other parts are fine - the microswitch which controls the inlet vaue was recently used as a replacement in the shower which is currently installed in the house.

Maybe it was a faulty batch?

 

[breezer]

i doubt it, when i was working fixing appliances, this was not a rare occurance, the wire would just burn out for what would appear to be no reason.

 

[Lectrician]

We have had many a call to showers that have done similar to this - this is the risk with high current devices.

The insulation of cables, and the enclosurs of electrical appliances are usually fire proof, and dsigned to resist a fire out break from over heating. I wouldnt trust them 100% though.

 

[Damocles]

Apparently the manufacturers do, if this is quite common.

 

[shaggy]

If it's common, I would expect them to get some feed-back and improve the design. Two of the connections to the heat exchanger have got crimped eyelets and screws which looks better to me, so why not all of them? The wire in the pic does look very close to have been on fire. I think I will do some tests on the insulation and shower cover to see if it will sustain a flame.
Ironically, the installation instructions state in bold print:
IMPORTANT: Fully tighten the terminal block screws and ensure that no cable insulation is trapped under the screws. Loose connections can result in cable overheating.
Good advice, they know their stuff then?

 

[shaggy]

I've had a very prompt reply from Triton but they don't say anything we didn't know. I was thinking they may have had a design problem that has been put right.

Thank you for your recent e.mail.

I am sorry to read of difficulties as detailed.

Based on the information available I would suggest that it would be
necessary to replace the outlet pipe assy and associated wires. With
regards to the actual cause of the problem this is a little more difficult
to give an accurate answer. It may be that the Secondary TCO itself was
the cause of the problem, wire or loose connection / crimp leading to a
high resistance joint.

Our Spares Dept would be able to supply any replacement parts for you and
may be contacted directly by telephone on 02476 372222. Alternatively
arrangements could be made for one of our service Engineer's to visit if
you would prefer this course of action.

I hope that this information is of help to you.

Regards,
Karl Stein
TECHNICAL TEAM.

Web Site: www.tritonshowers.co.uk

The good news is that I have held a flame under the cable and although it does catch fire, it extinguishes itself almost immediately the flame is removed so I think it is safe. I haven't tried the case as I may replace the thermal cut-out and wires and re-use it sometime.
(Of course I will have to install it before Part 'P' starts)

 

[L.Spark]

For the record, PVC like most modern plastics, altho won't sustain fire without melting, if they do catch light they are self extinguisihing, however if you had some Low Smoke and Fume cable it sustains the heat much better, and doesnt let off toxic fumes like PVC cable does.

 

[plugwash]

hmm when you described it to me you only mentioned meliting at the shower end

it sounds to me like a bad connection may have been a contributing factor

 

[shaggy]

Not with you plugwash. It did only melt at the shower end and the spade connection does look like it was a bad connection, but was nothing to do with me. The incoming mains wire was connected correctly to the terminal block.

 

[plugwash]

sorry shaggy i was refereing to LS