New Socket off a Switched FCU?

[actionjackson]

I need to add a single mains socket in a room for TV/SKY and the only power source in the room is a switched FCU which is a spur of the ring main.

The switched FCU is for a macerator pump but the FCU is installed outside the bathroom.


I would like to run surface mounted/1.5mm flex clipped to the wall from the FCU (load side) to a surface mounted single socket. The cable run will be 10m and i would like to replace the switched FCU with one with a flex output to make things easier.

Is this the best/correct method?

 

[JohnW2]

That sounds OK in principle (provided that the new socket is supplied from the load side of the FCU), but many would probably prefer you to use 'twin and earth' cable, rather than flex.

Regulations require that any new sockets are RCD-protected. Is the ring circuit in question already protected by an RCD?

Kind Regards, John

 

[actionjackson]

That sounds OK in principle (provided that the new socket is supplied from the load side of the FCU), but many would probably prefer you to use 'twin and earth' cable, rather than flex.

Regulations require that any new sockets are RCD-protected. Is the ring circuit in question already protected by an RCD?

Kind Regards, John

Thanks John

The ring circuit is RCD protected.

Should i consider doing this another way? I was 16th edition qualified 13 years ago but my career has gone in a very different direction so i'm not afraid to admit i'm no expert, but certainly know how to do a job correctly.

Any ideas what current a macerator pump pulls in operation?

Thanks

Neil

 

[JohnW2]

Thanks John ... The ring circuit is RCD protected.

That's a good start.

Should i consider doing this another way? I was 16th edition qualified 13 years ago but my career has gone in a very different direction so i'm not afraid to admit i'm no expert, but certainly know how to do a job correctly.

As I said, I think what you propose would be compliant with current regs (essentially, you can put whatever you like on the load side of the FCU of a fused spur), but many would probably consider it better practice to use T+E rather than flex.

Any ideas what current a macerator pump pulls in operation?

My Sanitop has a 400W motor (i.e. less than 2A running current) - although the start-up current might be appreciable. You're obviously limited to a maximum of 13A for everything on the load side of the FCU, but I would not have thought that macerator+TV etc. would be any problem at all. The macerator instructions may, of course, demand a fuse smaller than 13A in the FCU.

Others will probably have other views!

Kind Regards, John

 

[bernardgreen]

The start up current of a motor will always be greater than the running current until the motor reaches normal speed.

In the case of a macerator the motor may have to start when the macerator is full of semi-solid poo and thus the start up current will be higher and last longer. The voltage drop along the cable to the FCU due to the start up current may affect the TV / Sky equipment.

 

[JohnW2]

The start up current of a motor will always be greater than the running current until the motor reaches normal speed. In the case of a macerator the motor may have to start when the macerator is full of semi-solid poo and thus the start up current will be higher and last longer. The voltage drop along the cable to the FCU due to the start up current may affect the TV / Sky equipment.

All true - but I very much doubt that the start-up current would result in enough voltage drop to have any significant effect. Indeed, particularly if the FCU is on, or close to, the ring, the TV etc. would experience a fairly similar VD (due to macerator start up) no matter where it was plugged into the ring.

It so happens that the FCU for my macerator originates at the socket into which my Kitchen TV is usually plugged - and, FWIW, the TV doesn't bat an eyelid when the macerator starts up

Kind Regards, John

 

[PrenticeBoyofDerry]

Is the FCU wired as part of the RFC or is it a spur?

 

[actionjackson]

The start up current of a motor will always be greater than the running current until the motor reaches normal speed.

In the case of a macerator the motor may have to start when the macerator is full of semi-solid poo and thus the start up current will be higher and last longer. The voltage drop along the cable to the FCU due to the start up current may affect the TV / Sky equipment.

When i was in the trade 5 x running current was the rule of thumb for motor start up current . Thanks for the heads up, hopefully there will be no issues with voltage drop but i think I will be ok.

 

[JohnW2]

Is the FCU wired as part of the RFC or is it a spur?

a switched FCU which is a spur of the ring main.

... otherwise, of course, the OP could simply have taken a spur off the supply side of that FCU - but, with his background, I presume he would realise that.

Kind Regards, John

 

[JohnW2]

When i was in the trade 5 x running current was the rule of thumb for motor start up current . Thanks for the heads up, hopefully there will be no issues with voltage drop but i think I will be ok.

I agree. Even 5 times running current would be less that 9A for my Sanitop, and that's hardly going to produce a troublesome VD on a 32A circuit (or, if it does, you have bigger problems to worry about ).

Kind Regards, John

 

[PrenticeBoyofDerry]

Is the FCU wired as part of the RFC or is it a spur?

a switched FCU which is a spur of the ring main.

... otherwise, of course, the OP could simply have taken a spur off the supply side of that FCU - but, with his background, I presume he would realise that.

I know 17th ed qualified that don't know arse from elbow! So I would not assume any significant background knowledge, especially considering the OP cannot make an informed decision of their own (and no disrespect to the OP) but if they had got a 16th ed qual and had hands on experience to not even such a reasonable level, they would be able to suss this out.

 

[JohnW2]

I know 17th ed qualified that don't know a**e from elbow! So I would not assume any significant background knowledge, especially considering the OP cannot make an informed decision of their own (and no disrespect to the OP) but if they had got a 16th ed qual and had hands on experience to not even such a reasonable level, they would be able to suss this out.

That may be true but, whatever, if he was telling us the truth about the FCU being a spur off the ring, then he would not have had that option open to him, anyway.

Kind Regards, John

 

[securespark]

troublesome VD

I've had that.

 

[PrenticeBoyofDerry]

 

[JohnW2]

troublesome VD

I've had that.

Sorry to hear that! Is there a non-troublesome variant?

Kind Regards, John