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Discuss Electric UFH, Switch fuse sput hot/ in the Electric Underfloor Heating Wiring area at ElectriciansForums.net

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hi ALL,

I wired an electric UFH mat in a lounge, mat company said I can use this size mat for one programmer, it was at its max, I wired it separate back to the board, I fitted a switch fuse spur with a 13 amp fuse in, they were having trouble with it not switching off and when they switched it off at the fuse spur they said it was really hot.

i think its on a 16amp RCBO , should I change the switch fuse spur for a 20amp D.P switch ? . or try and split the mats onto two fuse spurs, I think there may be more than one mat on the programmer?

THanks
Grand
 
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littlespark

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Check the connections at the switch.... might be simple loose connection.

what is the calculated load for the mats? You just say it’s at its max.

did you find out why it didn’t turn off normally? Maybe the programmer is faulty.
Site visit to test programmer.
 
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It's an hour away from me, just had a text off the builder, will pop with another programmer, not sure on the mat rating, was told it was fine for a single programmer, mind you I think they are rated at 16 amps from memory. not sure, a bit concerned that the fuse spur was "mega hot", that's what they have told the builder, might change it for a D.P switch and make sure the RCBO is a 20 amp
 

littlespark

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You didn’t fit the mat? It was a builder?

That explains quite a lot actually.

Hope you charge accordingly.

Why would you have fitted a 13A fuse in the system in the first place if it can take 16?
 

ferg

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You didn’t fit the mat? It was a builder?

That explains quite a lot actually.

Hope you charge accordingly.

Why would you have fitted a 13A fuse in the system in the first place if it can take 16?
Some specify a fused spur even though they are rated at 16a. Nonsensical but presumably arse covering by the manufacturer.
 

littlespark

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Some specify a fused spur even though they are rated at 16a. Nonsensical but presumably arse covering by the manufacturer.
Quite possible, but the manufacturer will also say how many and what size mats can be used...
It’s beginning to sound like the builder has just installed the mats without adding up the total loads
 
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no sorry, i fitted the mat, I gave area and they sent mat, was a bit short so ordered another mat, spoke to the manufacturer and I wanted a 3m mat, he said I could only have another 2sq m as I would go over the limit. ordered , fitted, all working.
 

mattg4321

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Over the limit for the controller? Normally rated at 16A.

Sounds like you’re over 13A. Can you confirm?

Fused connection units/Spurs burn out if run at or close to 13A long term. Certainly will if over 13A.

Suggest you get there ASAP and swap for 20A DP switch assuming it’s on its own 16/20A radial.
 
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Been there, melting by the fuse ,click mode brushed chrome, fitted a D.P switch.

all ok now

i checked the programmer witch was fine but bloody hell those connections on the programmer are like the ones in fans, small green connections like on a PCB in boilers ,fans etc. but does say rated to 16 amps.


thanks for the help guys

Grand
 

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