Tenby FCU's

[razorback]

I have lost count of the amount of times I replaced Tenby FCU's. I replace them with MK's...anyway; tell me, when they fail I always carry out a post mortem on all FCU's, and one common fault they are all victims of and that is -not sure on the anatomical names for parts in an FCU - the two conical contacts on the switch seem to be very discoloured and evidence of "burning" I have just recently replaced another one and one of the contacts is completely melted away!!! Any explanation as to why that has happened. Cheers.

 

[wingcoax]

Constant switching on load?

 

[razorback]

constant switching on load, could you explain please?

 

[Taylortwocities]

With most devices (sockets, FCU s etc) when you turn the switch off the load is still connected and current is flowing.
If the load is relatively large then you may see a spark as the switch is operated. (ie switching on load)
If the switch is used a lot with the load connected, eventually it will not make contact quite so well, that can cause heat and may cause failure of the fitting itself.

 

[razorback]

I thought that's what it meant. It is storage heaters, so in terms of physically switching them on or off then that doesn't happen probably twice a year!! However, when they are on during the night, i don't think current is flowing all the time for 7 hours whilst its charging up. they are thermostatically controlled, so when the ambient temp is adequate it switches itself down but not necessarily off. when the temp is below a certain level the storage heater starts charging again and this continues for 7 hours. so would i be correct in saying that it is that kind of off and on that eventually causes the fcu to fail. i wander if tenby know there's a problem am sure they do. i have changed probably about 30 odd!!!!

 

[sparkwright]

I used Tenby switched fused spurs frequently for 20 years, even now use some 'old stock' which was from a clearance sale - never any problems.

It is recommended storage heaters and immersion heaters are fitted with 20 amp double pole switches.

 

[securespark]

Funny, the reason I replace most switched spurs is because the fuse tray is broken.

 

[securespark]

PLEASE REMOVE!!

 

[razorback]

Why? Securespark. This is the problem nowadays; when it is not obvious why a spur has failed - most sparks just simply remove it and replace it with another one. I open it up and try to find out why it has failed. It's like a nurse who has qualified and does not know about the anatomy and physiology of the human body. How could one truly be a nurse? I was simply trying to find the weak points within a tenby spur. Resistor too small? Something to do with the conical contacts? I don't know.