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[Elboy37]

Apologies for a long first post.

First, some background.

Domestic detached property with a footprint of approximately 74 m2 on ground floor and 70m2 on upper floor.

House is wired to sockets via two ring mains. The left ring main controls hall, dining room, kitchen and two bedrooms upstairs. Consumer Unit is protected with RCD MCUs.

I have made two additions to the kitchen on the left ring main in the kitchen.
1: Running a spur socket off another socket running the washing machine on the ring main.
2: Installing an 18w fluorescent light in a shed which uses the external kitchen wall for the switch and the light is on the ceiling approximately 55cm away from the switch.

Installation.
Existing: There is a 13amp switched FCU down near the floor on the external wall which I assume is spurred from the ring main. This switched FCU feeds a 13amp socket which powers the Dishwasher.

What I have done: I have installed a 3amp FCU and take 2.5mm twin & earth from the socket to the 3amp FCU. From the 3amp FCU I route 1mm twin & earth up the wall and through an air brick to the other side of the external wall which serves as one wall of the shed. I then take this twin & earth into an IP67 rated external switch sited on this wall approximately 10cm away from the air brick. I then run 1mm twin & earth to the 18watt fluorescent lamp which is sited approximately 55cm away from the switch.

What I want to do: Initially I wanted to install an external grade 3 way junction box to receive the cable as it emerges from the air brick and then continue on to the switch to control the light. Then run 1mm twin & earth to a 3amp FCU and on to a 10watt LED floodlight controlled via an integrated PIR.

Is this still OK to do?

Lastly, I want to put an external switched socket nearby, just outside the shed. I know that will be against the regulations if the dishwasher socket is spurred. I’m not sure how to tell if the socket is spurred or not!

One last question: I know the rule preventing me from powering two devices from a spurred socket. However, at the other end of the house I have a 10watt LED flood powered from a bedroom socket via a 3amp FCU. I want to daisy chain another 10watt LED flood using an external junction box. Total current drawn would be 20watts (I don’t know what current a PIR draws). If the bedroom socket powering this light is itself spurred then it would be against the regulations to add another device? Would this still be the case for another 10watt LED and if so, why?

Sorry this has been so long winded but I’ve tried to give you enough information to help me. If the job is going to be too difficult or complicated then I will need help finding a competent electrician.


Thank you for your time.

[Mr White]

Looking at your drawing you appear to have two supplies going to the junction box.
You are also over complicating things.
Once you have installed a fused connection unit, you can connect anything you like on the fused side, no need for any more FCU's. The reason being the first FCU will protect anything "down stream"

So what you could do, is to have an FCU on the ring, then "daisy chain" to what ever you like after the initial FCU providing you come from the fused side of the FCU.

[Elboy37]

Thank you for your reply. Yes, I have confused the issue. The lines in green are proposed and red are existing. However, I do accept I’ve overcomplicated things and only need one FCU.
I’m not sure but the dishwasher appears to be a spur from the Ring. Am I illegal for having an 18w light on the same circuit via the 3a FCU? If not, could I safely add another 10w LED floodlight?

[Mr White]

Who is going to know what you are doing is illegal or not?
The question should be is it safe, I have already answered that.

[ericmark]

I would say the Part P law is really a tax, when I notified no one checked, and when I tried to get a copy when selling the house, told need to wait 4 months.

Main point is 2.5 mm sq twin and earth is good for around 20 amps so once it goes through a FCU it can't really be over loaded.

Second is twin and earth is not round and so it is unlikely to seal any better than IP54, I normally ensure a hole in bottom so any water will drain out. Also a U before cable goes in so any water following cable will drip off bottom of U.

The regulations are not law, which is just as well as very few DIY people follow them.

[Elboy37]

I would say the Part P law is really a tax, when I notified no one checked, and when I tried to get a copy when selling the house, told need to wait 4 months.

Main point is 2.5 mm sq twin and earth is good for around 20 amps so once it goes through a FCU it can't really be over loaded.

Second is twin and earth is not round and so it is unlikely to seal any better than IP54, I normally ensure a hole in bottom so any water will drain out. Also a U before cable goes in so any water following cable will drip off bottom of U.

The regulations are not law, which is just as well as very few DIY people follow them.

Thanks for your information.