Garage Wiring Advice

[Lee Mason]

Hi all new member here.

First of all im not an electrictian, i have a sparky mate but hes on holiday and i wanted to get advice to get everything setup for his return (im aware of part p regulations etc so wont be doing it all myself).

Anyway just moved house and need some extra sockets in the single garage. Its a detached garage which has a armoured cable connection to the main cu via a mtn 116 hager 16a type b breaker.

In the garage is a little cabtree unit with a 6a breaker for the light, and a 16a type b breaker for the existing double socket.

Thats the existing setup, and this is what i need:

8x double sockets total.

2x above garage door for security lights (connected by fused plugs) and cctv cameras.

2x on each sidewall (1 will be used for another security light, the rest for occasional tool use).

1x external waterproof double socket unit.

Plus the existing double socket on the back wall, which will be used for:
1. an outdoor extension cable used for a fish pond
2. an outdoor extension for a light and thermostat tube heater in a dog kennel.


Being as there is only 1 double socket currently its just 1 cable runing strait to the socket with no return, which correct me if im wrong makes it a radial circuit?


What i want to do is run the cables and fix all the sockets to the walls ready so my mate can just come in and wire it all up to comply with the regs.

Will a 16a radial handle this? and due to the load is there any special wire specs i need to follow or use existing sized cable?

Or should this be converted to a 32a ring circuit? (which i guess would mean new breakers in both cu's and different cable sizes?

As i said above ive already mounted the backboxes and pvc trunking, just wanted to run the right cable and get any breakers if needed ready for when my mates back so he can actually make any connections.

 

[kenny7askew]

Hi and welcome,sorry to be a bit negative but its probably not worth fitting anything until your sparky mate as carried out a survey of your installation to decide what is the best way to proceed with what you require

 

[Richard Burns]

Welcome to the forum.
If you have already installed the containment then I would stick with what you have planned, 16A should be OK. Your friend would probably suggest a few changes, but it is a bit late to do so. The garage CU is a bit of overkill considering the supply protection.
Be careful on using extension leads outside they are often not suitable for permanent use in wet weather and the ends need to be inside a structure or containment.

 

[Deleted member 26818]

Problem here, is we don’t know the current carrying capacity of the armoured cable.
No point changing to a 32A ring if the armoured cable is only rated at 16A.
You’ll also need to provide RCD protection for the sockets, which may be easier to achieve by installing an RCBO.

 

[Lee Mason]

the pvc is 20mm and currently just goes to the roof void were the cables will run, so shouldnt make any difference i dont think.

Yes the extension leads would be inside outdoor boxes with those rcd plugs you can get and the kennel one would be inside an insulated weatherpoof kennel.

Regarding general rcd protection the house cu has 2 rcd units which the garage supply is connected to.

any idea how i would find out the armoured cable capacity, is it a width thing as i can go measure that if it helps.

 

[Octopus]

If you can see the outer casing of the SWA its often on it ......... if in doubt wait for your mate to reappear..........

What do you plan to put in the garage? Why so many sockets? The design load is crutial in such cases...........

 

[telectrix]

you could run 2.5 T/E cable from existing socket to all the new boxes that you have fitted (daisy chain). leave connections to your sparks mate. he can then determine whether to leave as a radial or just add some more cable to make into a ring final.

 

[Lee Mason]

The amount of sockets is conveniance really.

two doubles above door is a socket each for pir light and cctv camera and two spare (future cctv possibly, or door opener, or garage alarm).

double at back is a socket for fish pond, socket for kennel heater and light.

1 side socket for other pir light.

external socket for mower etc outside

and the others are all just easier access if i get my car polisher out, or need to use a sander/drill etc.

These extra sockets would be used infrequently and never all at one time.

Its a new built (2015) house and weve just moved in so wanted to put enough in and not have to think about changing anything later on.

Another thing just popped into my mind, would it make sense to wire the pir lights into the 6a lighting circuit instead and reduce the load on the plug circuit?

 

[Startinez]

Another thing just popped into my mind, would it make sense to wire the pir lights into the 6a lighting circuit instead and reduce the load on the plug circuit?

Depends what's already installed on the lighting really. If you've got a few fluorescent fittings then you could easily overload that circuit on switching with a few decent PIR lights as I'd imagine these will be a few hundred watts each? It would be rare but could be inconvenient for it to happen.

What is already installed, regarding lighting, in the garage? If fluorescents are present, B6 or C6 breaker?

 

[Lee Mason]

theres just one tube light on a switch with a b6 breaker.

 

[Startinez]

theres just one tube light on a switch with a b6 breaker.

Any idea on which PIRs are going in? What their wattage is?

 

[Lee Mason]

Ok theres a led one thats 30w and an "old school" one at 400w.

 

[Des 56]

What i want to do is run the cables and fix all the sockets to the walls ready so my mate can just come in and wire it all up to comply with the regs.

Your limiting factor is the supply,at present the 16 amp will have to do, irrelevant of how many outlets you intend to install
You can string as many as you want,divide the install into as many circuits and types you see as fit, you are restricted to what is the supply for this garage until or if its upgraded

 

[Startinez]

Ok theres a led one thats 30w and an "old school" one at 400w.

Wouldn't be a problem adding those to the existing lighting circuit then. It should be a C6 really as fluorescent lights have high inrush current on switching and C has a higher tolerance for that kind of thing than B. Probably worth spending £15 on while doing all the other works.

 

[Spoon]

Isn't there a reg for maximum wattage for outside lights? I thought that these high wattage ones are no longer allowed..

 

[Lee Mason]

interesting, i brought it from b and q a few months ago

 

[DPG]

I'd certainly be using a lower wattage LED fitting. Nearly half a kilowatt of power is going to get that meter spinning!

 

[Spoon]

interesting, i brought it from b and q a few months ago

I just done some searching on Google.
Check out Table 42 (page 84 of 92) on the pdf.
This states a max of 100W.
http://webarchive.nationalarchives....mestic_building_services_compliance_guide.pdf

 

[shaun1]

Wouldn't be a problem adding those to the existing lighting circuit then. It should be a C6 really as fluorescent lights have high inrush current on switching and C has a higher tolerance for that kind of thing than B. Probably worth spending £15 on while doing all the other works.

If changing to a C type breaker, you need to check the Zs of the circuit to make sure disconnection times are still met.

 

[Lee Mason]

Think ill stick to the pir lights on plugs to save any other alterations. Thanks for all the help so far.

On the actual wiring they run all round the garage with the cu in the middle.With the breaker being a 16a with 2.5 twin earth, a ring is just as easy as a radial, so just wondering if theres any limitations of a 16a ring? because havent yet confirmed the feed cable specs, and if thats also 2.5mm i cant make it a 32a ring.