3a FSU downstream of a spur socket from RFC - compliant?

[Rockingit]

Have a 3a FSU that feeds an adjacent WC light and fan, wired from a socket that is a spur. Even though we all know that it's safe (no different to having a 3a plug top in the socket), can't quite make up my mind if it's compliant or not. Thoughts?

 

[buzzlightyear]

Yes is compliant has long it's wired in correctly.

 

[littlespark]

spur from a spur. not compliant.

hate to disagree, but whether its a socket, or a 3A fcu... still a spur from a spur.
Perfectly safe, as you say, it could be a double socket with a 3A plugged in... no difference to the load on the cable branching off the ring.... but regs is regs

 

[Rockingit]

OK - the two polar opposite responses I expected. This application is fixed equipment…

 

[buzzlightyear]

Have a 3a FSU that feeds an adjacent WC light and fan, wired from a socket that is a spur. Even though we all know that it's safe (no different to having a 3a plug top in the socket), can't quite make up my mind if it's compliant or not. Thoughts?

Has above its one spur. Yes.

 

[Rockingit]

My reading of 433.1.204 suggests to me that it’s compliant

“…..Such circuits are deemed to meet the requirements of regulation 433.1.1 if the current carrying capacity (Iz) of the cable is not less than 20A and if, under the INTENDED conditions of use, the load current in any part of the circuit is unlikely to exceed for long periods the current carrying capacity of the cable.”

 

[JD6400]

Is it a double socket and fused spur or a single socket and fused spur ?

 

[brianmoooore]

Double or single socket?.

 

[timhoward]

spur from a spur. not compliant.

hate to disagree, but whether its a socket, or a 3A fcu... still a spur from a spur.
Perfectly safe, as you say, it could be a double socket with a 3A plugged in... no difference to the load on the cable branching off the ring.... but regs is regs

There is in fact no reg that says a spur off a spur is not allowed.
We don’t do it because the example diagrams of ways to comply with the only RFC reg don’t show it but it’s perfectly possible to comply with spurs off spurs.
I’ve done it in a large hotel lobby with 5A sockets for table lamps.

 

[Pretty Mouth]

This is an interesting question.

It goes against the design guide in appendix 15 (no spurs off spurs allowed). However, I don't believe there is any reg stating that app 15 has to be rigidly adhered to in order to comply.

IMO if the total load won't exceed the current carrying capacity of the cable running back to the ring, then it is compliant. In this case 20A for the double socket, and 3A for the FCU = 23A. So compliant if Method C.

Best practice? Perhaps not, the fused spur could easily be repurposed for a higher load. And you can bet a fiver of anyone's money that the next spark would condemn it, as it doesn't meet app 15.

 

[timhoward]

The main issue with it is that it’s unusual. And the next chap won’t like it. @Pretty Mouth beat me to it!

 

[buzzlightyear]

Chicken or the eggs job. What came first
Bulb or flower.

 

[timhoward]

Could we also go down the “fixed load” route as a light and a fan aren’t going to overload anyway? Tongue in cheek - no overload protection required unless manufacturer requires it for fan!

 

[Pretty Mouth]

Chicken or the eggs job. What came first

The egg, assuming you believe in evolution

 

[brianmoooore]

U

Could we also go down the “fixed load” route as a light and a fan aren’t going to overload anyway? Tongue in cheek - no overload protection required unless manufacturer requires it for fan!

Unfortunately, the fan isn't a fixed load. It can stall and draw increased current.

 

[timhoward]

If I’m reading it right , why not stick 3A fuse in plug and change FCU for a junction box?