13 amp supply to loft

[SuzieJarvis]

Hi all,

I'm going to fit 2 new Aqua Lisa pumped showers, so need to install a 13amp supply in the loft. Can this supply be a spur (bearing in mind both pumps could be running at the same time or does it need to loop back to the ring?

Alternatively, I have an existing dedicated 10mm T&E (I think) that is feeding a Triton electric shower that is going to be ripped out and never seen again. Could I use that feed (which is directly off its own breaker on the distribution board) to feed the shower pumps?

Many thanks, SJ

 

[oharaf]

You could use the existing shower supply if it meets requirements re-safe zones etc. You would need to down rate the MCB.

A fused spur is also another possibility. What are the maximum wattages for the shower pumps?

 

[SuzieJarvis]

You could use the existing shower supply if it meets requirements re-safe zones etc. You would need to down rate the MCB.

A fused spur is also another possibility. What are the maximum wattages for the shower pumps?

Safe zone not an issue. Not sure on the wattage for the shower pumps but AquaLisa reckon it's OK to rum them off the lighting circuit... I don't feel too comfortable with that myself...

 

[electronicsuk]

If you take a spur from a suitable point on the ring final and protect with an FCU then you can have as many loads on it as you like up to 13A. As shower pumps don't normally require a lot of power, you may want to install an FCU with 13A fuse as the point of spurring, and then from the load terminals feed a pair of FCUs in the loft both fitted with 3A fuses.

 

[SuzieJarvis]

... and then from the load terminals feed a pair of FCUs in the loft both fitted with 3A fuses.

Hi electronicsuk,

Many thanks for this. Is taking more than one FCU from the load terminals strictly kosher? I will arrange for a qualified electrician to check everything on completion, but don't want him/her to tell me that it isn't 100% correct....

 

[electronicsuk]

... and then from the load terminals feed a pair of FCUs in the loft both fitted with 3A fuses.

Hi electronicsuk,

Many thanks for this. Is taking more than one FCU from the load terminals strictly kosher? I will arrange for a qualified electrician to check everything on completion, but don't want him/her to tell me that it isn't 100% correct....

Absolutely, as everything on the load terminals is protected by the fuse in the FCU, so there is no possibility of a damaging overload.

 

[SuzieJarvis]

Absolutely, as everything on the load terminals is protected by the fuse in the FCU, so there is no possibility of a damaging overload.

Thanks, sounds the easiest solution.

Just one more (possible silly) question... Should the two cables from the load terminals on the 13A FCU (one 3A for each shower pump) be flex or T&E? If flex, is there a safe limit of how long the run can be?

 

[electronicsuk]

Absolutely, as everything on the load terminals is protected by the fuse in the FCU, so there is no possibility of a damaging overload.

Thanks, sounds the easiest solution.

Just one more (possible silly) question... Should the two cables from the load terminals on the 13A FCU (one 3A for each shower pump) be flex or T&E? If flex, is there a safe limit of how long the run can be?

Normally you would use T+E or similar solid conductor cable for fixed wiring. There's no need to run two separate supplies from the load terminals of the first FCU. Simply go ring final > 13A FCU load terminals > loft > 3A FCU supply terminals, and then daisy chain the second 3A FCU supply terminals off those of the first.

If you use cable with 1.5mmsq conductors from the load terminals of the 1st FCU then that should be more than adequate, but 2.5 is also fine if you have it to hand.

 

[planemad]

I to had a redundant 10mm feed in my loft that I wanted to utilise when I got my digital shower.
What I did was use the 10mm cable to feed a mini consumer unit (2 way) from which I ran a ring main in my loft with three double sockets.

Seems a lot for a loft but I have my digital shower plugged in I also have my bathroom extractor plugged in and also have the main tv aerial booster plugged in.
With the other way on the CU I have run a lighting ring with gives me a loft light, exterior soffit lighting for the front and b and a large garden security light.

I made sure to mark the main consumer board downstairs and the shower DP isolator with what it supplied.

 

[ban-all-sheds]

a lighting ring

Why on earth did you make it a ring?

What a waste of cable.

 

[planemad]

I'm training at the moment and carried out some practical that we covered at college.
Also on the lighting ring I have 1 loft light and switch, front and back soffit lighting on a timer and override switch and I also have a 500w flood light on pir and a switch.

 

[SuzieJarvis]

Normally you would use T+E or similar solid conductor cable for fixed wiring. There's no need to run two separate supplies from the load terminals of the first FCU. Simply go ring final > 13A FCU load terminals > loft > 3A FCU supply terminals, and then daisy chain the second 3A FCU supply terminals off those of the first.

If you use cable with 1.5mmsq conductors from the load terminals of the 1st FCU then that should be more than adequate, but 2.5 is also fine if you have it to hand.

Hey - many thanks. Wired in a couple of 3A FCUs (using 2.5mm T&E to be on the safe side) of the 13A FCU spurred off the ring and everything seems fine and ticketyboo.

I wired 13A load to first 3A supply, then daisy-chained the 3A supply to the 2nd 3A supply, the took off two 3A loads to the shower pumps.

Again - many thanks for the advice. SJ

 

[SuzieJarvis]

Moving on a bit... I now have a redundant 6mm T&E that fed the old electric shower. It is on a dedicated breaker in the consumer unit. I am looking to install underfloor heating inthe bathroom, but was struggling to find a neat and easy way of getting a decent power supply to it from the existing ring. Can I use this redundant cable to power the underfloor heating? I thought if I terminated the 6mm cable in a 13A FCU, then came off that in 2.5mmT&E to the underfloor heating.....

 

[bongos]

You can do as you propose. Does the redundant circuit already have RCD protection?

This work would be notifiable to your LABC, as i'm sure will have been mentioned somewhere.