Outdoor electrical wiring

[harry1001]

Hi

I'm doing some outdoor wiring and I have a few questions I'm hoping some knowledgeable electricians can help with.

1. Wiring to garage. I have a kit which you drill a hole through the wall and plug one socket in to the household supply via an RCD plug and then an outdoor IP65 socket attaches outside. From that i'm running some 1.5mm cable to a garage socket for occasional power tool use and general lighting (max consumption 2kw) - I thought for 1.5mm cable you use a 13amp fuse but someone told me to use a lower rated fuse 10amp? do you generally use a fuse with lower rating than the cable/flex?

2. The general garage lighting is 4 x 60w bulkheads. The instructions say to use 1mm cable but I have 0.75mm cable. Is the 0.75mm cable ok via a 3amp fuse?

3. Outdoor lights. from the second of the IP65 sockets i'd like to run 2 sets of lights from a two way switch. The lights are rated 100w and 120w. is it ok to use the 0.75mm cable again with a 3amp fuse to the switch and then from the switch to each set of lights or would I need a larger cable diameter?

Thanks

 

[EFLImpudence]

1. Wiring to garage. I have a kit which you drill a hole through the wall and plug one socket in to the household supply via an RCD plug and then an outdoor IP65 socket attaches outside. From that i'm running some 1.5mm cable to a garage socket for occasional power tool use and general lighting (max consumption 2kw) -

Where will the cable run?
Will you be leaving the cable permanently plugged in or only using when required?
How far is the Garage? (Although I suppose no further than the 'kit' allows)

I thought for 1.5mm cable you use a 13amp fuse but someone told me to use a lower rated fuse 10amp? do you generally use a fuse with lower rating than the cable/flex?

Well, yes, of course. That is the point of it.
However, 1.5mm² flex is rated at 16A.

2. The general garage lighting is 4 x 60w bulkheads. The instructions say to use 1mm cable but I have 0.75mm cable. Is the 0.75mm cable ok via a 3amp fuse?

It will be fine electrically but there is a regulation stating a minimum of 1mm² for lighting circuits except to specific items so ...

3. Outdoor lights. from the second of the IP65 sockets i'd like to run 2 sets of lights from a two way switch. The lights are rated 100w and 120w. is it ok to use the 0.75mm cable again with a 3amp fuse to the switch and then from the switch to each set of lights or would I need a larger cable diameter?

As above but yes that will be alright.
I presume you mean a two-gang switch.

 

[harry1001]

many thanks for your reply

It will be plugged in all the time in the socket on the outside of the house but won't be switched on unless needed (the outdoor socket is an IP rated switched socket). The cable (with plug) will then plug in to that socket, run along the outside of a building and to a second socket in the garage (I plan to treat it a bit like a permanent extension lead as at the moment I have to keep winding a lead out and in from inside the house each time I want to work in the garage) and the garage is about 20/25m away.

Also - if the plug in the house has a built in RCD adapter on it (part of the kit) and the outdoor socket (attached to the house) has a built in RCD, would it be advisable to have an RCD socket in the garage as well even though the electricity will come through these two RCDs - or would it be safer to have RCD protection in the garage as well i.e. 3 RCD devices on the same supply

Many thanks

 

[ban-all-sheds]

The cable (with plug) will then plug in to that socket, run along the outside of a building and to a second socket in the garage

That could well be unsafe, and (therefore) illegal.

If you want a permanent supply to the garage then please do it, or have it done, properly. A "permanent extension lead" won't do.

Also - if the plug in the house has a built in RCD adapter on it (part of the kit) and the outdoor socket (attached to the house) has a built in RCD

So the kit you bought has an RCD socket and an RCD plug to supply it?

How bizarre.

would it be advisable to have an RCD socket in the garage as well even though the electricity will come through these two RCDs

Pretty pointless - you'd have to have the other two both go wrong for the one in the garage to be of any use.

And possibly not even then....

or would it be safer to have RCD protection in the garage as well i.e. 3 RCD devices on the same supply

3? Or 4? Is the socket in the house you're planning to use for this lash-up RCD protected?

 

[harry1001]

Thanks.

What makes it unsafe/illegal? I don't understand the difference if I run my extension cable from the outdoor socket to the garage each time I want to use it or if I use a cable that's permanently fixed in place but only switch on when infrequently required?

The cable will run along my wall on my land

Many thanks

 

[RF Lighting]

Extension leads don't get damaged when they're coiled up and stored in your cupboard. Unsuitable types of cables fixed outside exposed to rain, sunlight, impact, fauna attack etc even when they're not in use do get damaged.

 

[bernardgreen]

What makes it unsafe/illegal? ~~~~~ ~~~~The cable will run along my wall on my land

As already mentioned extension cables deteriorate when continuously exposed to the atmosphere and thus become dangerous.

Even though the cable is on your land you still have a duty of care to everyone who comes onto your land. That includes unwanted visitors such as trespassers and those with criminal intent. If that cable causes them injury they can sue you and would win unless you could prove the installation was done properly and was therefore safe.

 

[skotl]

I completely agree with all of the advice posted on here - definitely not a good idea, but;

That could well be unsafe, and (therefore) illegal.

While I concur with it being unsafe, and also accept Bernard's point about duty of care and liability, I'm having a hard time seeing this being "illegal" and, by extension (har har) leading to the OP being arrested and carted down to the local nick.

I think the warnings and advice on this thread are clear and strong enough without needing any additional hyperbole regarding legality.

 

[JohnW2]

I completely agree with all of the advice posted on here - definitely not a good idea, but;

That could well be unsafe, and (therefore) illegal.

While I concur with it being unsafe, and also accept Bernard's point about duty of care and liability, I'm having a hard time seeing this being "illegal" and, by extension (har har) leading to the OP being arrested and carted down to the local nick. ... I think the warnings and advice on this thread are clear and strong enough without needing any additional hyperbole regarding legality.

Whilst I agree with the spirit of your final sentence, what BAS wrote is actually fact, not hyperbole. Part P of the Building Regulations (which are 'law') require that all domestic electrical work be undertaken safely ("reasonable provisions will be made to avoid ...."). Any such work which is considered/deemed to be 'unsafe' is therefore, by definition, strictly 'illegal' per that law ... not that arrest and the local nick come into the equation!

Kind Regards, John

 

[harry1001]

Many thanks to everyone. I see the issue/risk is the cable so even though the cable to the garage will only be live when I use it (as i'll switch it on and off at the house when I need it) there is a risk I could forget to switch it off and also over time it will degrade and cold become dangerous. What if the cable used was SWA armoured cable?

 

[JohnW2]

Many thanks to everyone. I see the issue/risk is the cable so even though the cable to the garage will only be live when I use it (as i'll switch it on and off at the house when I need it) there is a risk I could forget to switch it off and also over time it will degrade and cold become dangerous. What if the cable used was SWA armoured cable?

If SWA were used (which it should be for a 'permanent' outdoor installation), the installation would have to be done 'properly' - you can't just attach a plug to SWA and plug in into a socket in the manner you were planning to do.

Kind Regards, John