9.5kw"TRITON OPAL 2" BURNT WIRE

[the BLUEGALOO]

hi, i had a problem recently with my shower, when it was switched on it kept flicking to low pressure even though the pressure was fine. i opened it up to find that the 10mm pos wire from the terminal block was black and burnt melting away at least 2" of insulation. i also discovered that the wire used to connect it is 2mm solid core... obviously all wrong..... yet what i dont understand is how the 10mm cable got so hot to melt although the 2mm is fine

any help is appreciated

 

[ban-all-sheds]

Loose connection.

Is there enough slack in the cable to allow you to cut it back past the point where the insulation is damaged?

BTW - didn't you ever smell anything?

 

[ColJack]

do you mean 2.5mm² twin and earth?
or is the diameter of the cable about 2mm? because that's roughly the diameter of 6mm² cable..

the cable gets hot when there is a loose connection, the contact is bad so all the current has to go through a smaller area than it needs effectively reducing the CSA of the conductor..

 

[the BLUEGALOO]

no was searching on here last night and noted about loose connections so checked that today there is no movement at all in the wire.

and in answer to the question suprisingly no one noticed any burning smell. yet this must have been happening for a while.

also noted quite a bit of green verdigree forming on the copper, i have a theory that the 2 hours constant running each night as the woman showers turning the bathroom into a steam room is to blame

what you think

 

[the BLUEGALOO]

do you mean 2.5mm² twin and earth?
or is the diameter of the cable about 2mm? because that's roughly the diameter of 6mm² cable..

no it seems to be done in 4 core 2mm conductor fire cable... as stated before seems very wrong

 

[ban-all-sheds]

or is the diameter of the cable about 2mm? because that's roughly the diameter of 6mm² cable..

2.76mm.

A conductor with a diameter of 2mm has a csa of approximately 3.14159265358979323846264338327950288419716939937510mm²

 

[ColJack]

ok, so I forgot my basic maths... there's been a lot more info crammed into a rather limited space since I did this stuff in primary school... something was bound to get pushed out..

for some reason i got 2PixR or PixD in my head, but that's circumfrence..

 

[the BLUEGALOO]

no was searching on here last night and noted about loose connections so checked that today there is no movement at all in the wire.

and in answer to the question suprisingly no one noticed any burning smell. yet this must have been happening for a while.

also noted quite a bit of green verdigree forming on the copper, i have a theory that the 2 hours constant running each night as the woman showers turning the bathroom into a steam room is to blame

what you think

 

[ColJack]

it's not that there might be movement in the cable, can you tighten the screw anymore?

you might only be clamped properly onto 4 or 5 of the 7 strands in the cable if the screw terminal is too large..

many cables "settle" after a few uses ( especially the larger size ones as these tend to be munlticore.... )
many manufacturers recomend checking the tightness of screw connections after the unit has been commissioned..

while you're at it, check the connections in the switch....

you say 4 core "fire cable"? do you mean the hard copper coated stuff with powder in it? this stuff has no insulation to melt ( the insulation added on the wires is usually high temperature silicone rubber.. ) and can take more current than the same sized T+E..
also you say 4 core.. are the cores paired up?

and where does this 10mm come into it? I'm confused now..

is the 2mm internal wiring in the unit? or is the 10mm?

 

[wilsya]

got the same prob too the 7 inch long live cable from pcb to can element overheated an melted the insulation, i see one strand split so i guess the resistance increased and therfor the heat on the cable to a point that it melt insulation