Domestic elecrical gurus

johnboy · 13/9/19

Are there any electrical gods in the house?
I want to bury a run of some twin and earth around 25 metres in length to an outside weather proof socket. At the shed end it will have a regular three pin plug and be plugged into a standard socket, go through the wall and buried in the ground and appear around 25 metres later in the garden where it will go into a IP66 dual gang socket. Do I need up-rated twin and earth? Essentially it is going to be a more permanent solution to running an extension lead out.

andyBeaker · 13/9/19

johnboy said:
Are there any electrical gods in the house?
I want to bury a run of some twin and earth around 25 metres in length to an outside weather proof socket. At the shed end it will have a regular three pin plug and be plugged into a standard socket, go through the wall and buried in the ground and appear around 25 metres later in the garden where it will go into a IP66 dual gang socket. Do I need up-rated twin and earth? Essentially it is going to be a more permanent solution to running an extension lead out.

Armoured cable.

I'll put a link up in a minute.

You should also run plastic warning tape over the installation for when someone starts digging a hole in twenty years time.....I can send you some if you like.

Not too convinced by the plug arrangement but I may be misunderstanding. Are you saying that the new cable will have a three pin plug at one end??

Thinking about it, you can't put a three pin plug on armoured cable in any event as it needs a gland fitting.

Link to follow....

andyBeaker · 13/9/19

https://www.tlc-direct.co.uk/Main_Index/Cable_Index/Armoured_SWA/index.html

You need two core cable, the armoured outer acts as the earth which is why you must use gland fittings.....

andyBeaker · 13/9/19

Glands......

https://www.tlc-direct.co.uk/Main_Index/Cable_Accessories_Index/Glands_SWA/index.html

2.5mm SHOULD be enough for most applications BUT it depends on what you propose to run from it and how the supply to the shed has been done.. There are loads of calculators online to make sure you have a thick enough cable, but TLC are really helpful and will point you in the right direction.....

andyBeaker · 13/9/19

In the shed what you need to do is break into the existing circuit rather than using a three pin plug. A couple of ways of doing 'tis - do you know if the circuit is on a ring main (i.e. Two cables into socket) or a radial (one cable in to socket)??

johnboy · 13/9/19

andyBeaker said:
In the shed what you need to do is break into the existing circuit rather than using a three pin plug. A couple of ways of doing 'tis - do you know if the circuit is on a ring main (i.e. Two cables into socket) or a radial (one cable in to socket)??

Both are available in the shed/outhouse radial is the preferred socket due to ease of access.

andyBeaker · 13/9/19

johnboy said:
Both are available in the shed/outhouse radial is the preferred socket due to ease of access.

This should help.

2.5mm SHOULD be ok unless you are running power hungry stuff off the circuit.

Bear in mind you need to consider the length of the cable running to the new armoured cable when using the calculator.

https://www.tlc-direct.co.uk/Techni...MIipic88fO5AIVRLDtCh1vXA-sEAAYASAAEgIr0vD_BwE

andyBeaker · 13/9/19

I'll post up a 'how to' tomorrow....coincidentally I laid an armoured cable to the front garden where we were having the drive done, not fully connected yet so a perfect opportunity for a photo of how the gland works......it is very straightforward...youtube is your friend!!

Centaur · 14/9/19

I thought this was a motorbike site! Where does this cable fit on a Blackbird? Is this a new loomfix?

slim63 · 14/9/19

I am no sparky but this is what I was told when I wired up my shed

It depends on what you want to run from the outside socket as to what armoured cable you need, if for example you were running a welder which pulls a lot of amps you will need a higher rated cable, cable should be 1m down but rarely is

its is always best to come from a spare breaker in your consumer unit rather than off the existing ring main so all the outside stuff is on a dedicated breaker & never use 2 breakers IE the one on the consumer unit & another in a shed or whatever

And its perfectly legal to do it yourself as long as its done to the correct spec

Oldandbald · 14/9/19

I'd say that this comes under part p of the buildings regulations and is notifiable to the local authority. Garden lighting or power supplies are specified as "special locations". At the very least the new circuit needs to be protected with an rcd which may not be present if the existing consumer unit is elderly.

Doesn't mean you can't do the work yourself but it will need to be inspected and signed off by a competent person under the scheme.

Oldandbald · 14/9/19

And I would completely agree with what slim63 just posted above. You should always look to come straight off a separate breaker in the consumer unit for an outside supply. The added benefit is that you can usually use an rcbo instead of an mcb to provide the required earth leakage trip if there isn't one already present.

andyBeaker · 14/9/19

Spot on with RCD stuff above...I hadn't quite got that far,as,I,was,tired!!

Hopefully there is capacity within the existing consumer unit.......ordinary cable can be run from this to the point where the armoured cable kicks in to keep the cost down. If the existing consumer unit doesn't have RCD then 'shed' units with RCD are available that will protect the new circuit only.

I wonder how many houses would get a certificate covering exterior electrics installed years ago...I visit quite a few properties where they are all in standard cable...both above and below ground.....

Oldandbald · 14/9/19

I agree. I've seen loads of installations done by "competent persons" that are complete crap. A reasonably competent DIY'er will usually do a far better job as they aren't constrained to sticking to a quote and having to rush the job through.

If this is just to run a double socket in the garden then 2.5mm twin and earth from a 16amp breaker (or rcbo) in the consumer unit will be fine. Run this inside the house to an adaptable box where you can tidily terminate the armoured cable.

Squag1 · 14/9/19

Ummmmm
I came across lights over a wash basin in a bathroom wired from the pull cord shower switch.

Definitely make your eyes light up!

Oldandbald · 14/9/19

Squag1 said:
Ummmmm
I came across lights over a wash basin in a bathroom wired from the pull cord shower switch.
Definitely make your eyes light up!

Hopefully that was somewhere close to a fire station.

andyBeaker · 14/9/19

In my second house I was doing a complete rewire (as you were allowed to in those days..), the mains supply was switched off totally.....and I grabbed a wire under the floor in a bedroom and got a massive shock.

Turned out it was running off next doors supply.......

Now, call me a cynic, the house was originally the show home for the estate and was subsequently owned by the developer's sister.......

As an aside, our house was about a foot bigger each way in just about every room compared to the surrounding 'identical' houses. Now, call me a cynic again...show home....new estate...rooms bigger than all the other places. Hmmmm

Squag1 · 14/9/19

Allegedly here on larger developments the site foreman would tighten up the houses on the longer roads and fit in another built from spare materials and sell it himself

A guy who worked in Dublin city council told me they had to watch one particular developer who always tried to fit in extra houses beyond what he had permission for.

DEG5Y · 14/9/19

OMG Beakers sparking now!!!

Whilst you can use the armouring of the cable as the earth, I wouldn't rely on it.
A buried cable can get damaged without realising it, the armouring can then be subject to water ingress which could result in no earth, eventually.
Three core SWA, with the armouring bonded at each end.
Buried at least a spade and a half deep all the way.
Personally I would fit a 'garage' consumer unit in the shed as these 'it's only for' always get bigger!
Cable size should be calculated for the anticipated load and the way the cable is run. But a double skt (max 26Amps), 25m and buried should be around 2.5
but should you go down the consumer unit route then I would look at at least 4mm.
And yes, if your consumer unit is RCD protected feed it from the protected side.

Disclaimer - This is only a rough guide and you should ask a local spark that can actually see the route.

Remember Beaker, plumbing gets people wet, sparking kills!

slim63 · 14/9/19

DEG5Y said:
OMG Beakers sparking now!!!

Whilst you can use the armouring of the cable as the earth, I wouldn't rely on it.
A buried cable can get damaged without realising it, the armouring can then be subject to water ingress which could result in no earth, eventually.
Three core SWA, with the armouring bonded at each end.
Buried at least a spade and a half deep all the way.
Personally I would fit a 'garage' consumer unit in the shed as these 'it's only for' always get bigger!
Cable size should be calculated for the anticipated load and the way the cable is run. But a double skt (max 26Amps), 25m and buried should be around 2.5
but should you go down the consumer unit route then I would look at at least 4mm.
And yes, if your consumer unit is RCD protected feed it from the protected side.

I ran 6mm 3 core from an adaptable box off a spare breaker in the consumer unit for the earth reasons you mention above & the fact that I would be running a welder in the shed + lights & whatever else I need at the time, not managed to trip it or elctrocuted myself yet so the advice seems sound

One thing that did confuse me for a moment was the new wiring colours on armoured but it wasn't a problem once I'd asked & looked it up

As I understand it part P only says work must be done in accordance to the rules by a competent person IE anyone with half a brain

getting it signed off is really a bunch off toss as it only really matters if you come to sell the place & then you or you buyer will be getting a survey anyway & the sparky gets a stupid amount of cash for plugging in a tester

Mine is signed off by the way, mates a sparky so it might cost me a pint at some point

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