Cutting The Element Cable??

[Tom @ APS]

Hello Guys,

Newbie question coming up, any advice welcome..

My dad has asked me to install electric UFH in his new shower room. The problem is that he has bought too much matting (4sqm). He asked about cutting the mat then splicing on the termination end. I am not an electrician but I know enough to know that this will not be suitable and he will be re-purchasing the correct amount.

But for interest, why is it not possible to cut the heater cable and re-splice on the termination end? Is this because the resistance for the heater cable would become incorrect for the new length, is there a resistor in the termination end??

Again, this course of action will DEFINITELY not be conducted, I am only interested in finding out more about how the system is constructed.

Any ideas?

Tom

 

[pjrich]

Hi Tom.

I will try to explain by heating cables & mats cannot be cut.

Your mat is 4m2 and say 160W/m2, then the total power is 640W.

The total power is 640W, Voltage is 230V, then the resistance is 82.65 ohms (using Res = (VxV) / Power)

If the cable on the mat is 64metres (10W/m) then the resistance per metre is 82.65 / 64 = 1.29ohms per metre.

Say you reduce the mat by 25%, i.e. cut 1m2 off the mat. This would mean that the heating cable/element on the mat would now be 48 metres long. With resistance of 1.29ohm/m then the total resistance would be 61.92ohms

Therefore, the total power of the heating mat is now = (230x230) / 61.92 = 854.33W !!!

So the heating cable is now 17.79W/metre, not 10W/metre. After period of time the heating will burn out.

Most heating cables / mats are fixed wattage and therefore cannot be cut, the only exception to this are self regulating cables which are generally not used for under tile heating.

Hope this answers your question.

Warm Regards,

Peter

 

[Uheat]

Hi Tom.

I will try to explain by heating cables & mats cannot be cut.

Your mat is 4m2 and say 160W/m2, then the total power is 640W.

The total power is 640W, Voltage is 230V, then the resistance is 82.65 ohms (using Res = (VxV) / Power)

If the cable on the mat is 64metres (10W/m) then the resistance per metre is 82.65 / 64 = 1.29ohms per metre.

Say you reduce the mat by 25%, i.e. cut 1m2 off the mat. This would mean that the heating cable/element on the mat would now be 48 metres long. With resistance of 1.29ohm/m then the total resistance would be 61.92ohms

Therefore, the total power of the heating mat is now = (230x230) / 61.92 = 854.33W !!!

So the heating cable is now 17.79W/metre, not 10W/metre. After period of time the heating will burn out.

Most heating cables / mats are fixed wattage and therefore cannot be cut, the only exception to this are self regulating cables which are generally not used for under tile heating.

Hope this answers your question.

Warm Regards,

Peter

What Peter Said!!!!

 

[Gazzer]

Wooooosh :lol: (right over my head)

 

[Uheat]

Wooooosh :lol: (right over my head)

lol....:lol:

It gets him all excited when he can talk like that!!

 

[Fred]

Top info.

 

[Aztectiler]

and in english please!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[White Room]

Straight past me:yikes:

 

[DHTiling]

and in english please!!!!!!!!!!!!!!!!!!!!!!!!!!!!

He means NO.......:smilewinkgrin:

 

[Tom @ APS]

Thanks for the response Peter, that clears that one up.

Also quite a nice re-fresher lesson in high school physics etc!

Usefull and informative.

Thanks,

Tom