switched fcu question.

[entech]

switched fcu installed on a ring main. what would happen if one leg of the supply live was crossed over with the load live. am i right in thinking that the appliance would always be powered on ?? or would it be dependenat on the switch as if it was wired correctly?

are they DP switched??

 

[telectrix]

fcu's are single pole switching. if you cross the L in and L out, it will still switch, but obviously needs to be rectified.

 

[Johno]

I am pretty sure that FCUs are DP,.

If you connected the live to the load with the one of the supply lives then the load would have a permanent live and would be be switched with neutral. And when switch is off, the continuity of the ring would be switched off.

So even though everything would still appear to work, it needs sorting sharpish!

 

[entech]

Thanks for reply, so the appliance would always be on regarding the switch position and you would be switching the ring i.e
switch closed =ring

and

switch opened= breaking ring (2 radials)???

 

[Johno]

The appliance would turn off, because you would be switching the neutral!

 

[Johno]

But yeah, you would in a way be making 2 radials when switch is off.

 

[entech]

I am pretty sure that FCUs are DP,.

If you connected the live to the load with the one of the supply lives then the load would have a permanent live and would be be switched with neutral. And when switch is off, the continuity of the ring would be switched off.

So even though everything would still appear to work, it needs sorting sharpish!

It would only ever pose a problem then when the switch was opened?? (turned off)

 

[Johno]

No, because the appliance isn't protected by the fuse in FCU.

And you CANNOT have the switch in the neutral!

And it's just wrong, it really does need sorting

 

[entech]

No, because the appliance isn't protected by the fuse in FCU.

And you CANNOT have the switch in the neutral!

And it's just wrong, it really does need sorting

Yes totally agree, thanks.

 

[Johno]

No probs.

Imagine if you go to fix an appliance, turn off FCU and appliance goes off, you would probably assume that it is dead and then start messing with live cables.

 

[entech]

Good reason for safe isolation.

Assume = making an "---" out of "u" and "me".

I always remember being told that.

 

[Johno]

Obviously you should test it first before sticking your fingers in, but that doesn't mean that we all do all the time.

 

[entech]

just one other question,

in a correctly wired switched fcu , is it psossible to get one where the neon would indicate that you had a supply voltage as opposed to the neon indicating the load is switched on??

 

[Johno]

Not that I have seen, the neon is connected to the load side of FCU

 

[Spudnik]

FCU's are single pole, however, most SFCU are DP.