Armoured cable connections

[justins]

Here's my setup:

New external meter cabinet with Meter and DNO isolator / fuse.

Here's what I want to do:

Take power from this cabinet (using UG SWA cable) to:

1. Main house consumer unit
   
2. Shed / garage consumer unit
   
3. Borehole water pump shed consumer unit.
   

1, 2 and 3 are all about 30m from the cabinet, in different directions, but not completely different directions (ie taking junctions off a single cable would save a lot of cabling.

Would appreciate some advice on the best way to to this please - size of cable, numbers of cables, fuses, equipment in meter cabinet.

Thanks.

 

[Spoon]

Welcome to the forum.

Depending on where you live. This work will be notifiable.

Shouldn't the electrician who is designing, installing, testing and putting their name on the certs be designing this for you?

I'm not giving out cable sizes, this is down to the electrician, but wouldn't the best option be:

Go from meter to house CU.

Wire shed & borehole CU's to house CU.  (This all depends on whats going in the shed)

 

[Pete10001]

elcome to the forum.

Depending on where you live. This work will be notifiable.

Shouldn't the electrician who is designing, installing, testing and putting their name on the certs be designing this for you?

I'm not giving out cable sizes, this is down to the electrician, but wouldn't the best option be:

Go from meter to house CU.

Wire shed & borehole CU's to house CU.  (This all depends on whats going in the shed)

Agree with Spoon, anyway you haven't mentioned any loading details, installation methods etc as Spoon said all down to the Electrician doing the work

 

[Sharpend]

Are you the installing electrician? 

Are you the property owner? 

Are you the tenant? 

What at are you hoping of having in the shed/garage? 

What are the ratings of the bore pump? 

What type of supply have the DNO given you? 

 

[justins]

Are you the installing electrician? 

Are you the property owner? 

Are you the tenant? 

What at are you hoping of having in the shed/garage? 

What are the ratings of the bore pump? 

What type of supply have the DNO given you? 

Please don't read me the rule book guys. Just some friendly advice? I wouldn't dream of doing anything that I wasn't qualified to do, even after having asked advice from those who are to ensure that everything was safe.... I'm clearly not the installing electrician or I wouldn't be asking. Tenant is unlikely to be installing a bore pump. I'm the property owner.

Knowing what is involved and the best way to do this will help me to cost parts for the job and to plan my trenching. Also give me some know how when discussing options with my electrician (I haven't employed one yet)

Shed: 1 lighting circuit for 3 or 4 lights, one 13A ring main (maybe a dozen sockets) to run power tools etc

Bore pump: 2kw

 

[Spoon]

Knowing what is involved and the best way to do this will help me to cost parts for the job and to plan my trenching. Also give me some know how when discussing options with my electrician (I haven't employed one yet)

Very true mate.

The thing is, your electrician will give you all this info.  Where best to dig trench & at what depth......

Wiring wise, I would go with what I suggested above.

 

[justins]

 (I haven't employed one yet)
 

 

[Spoon]

(I haven't employed one yet)

Yes mate, I got that from your previous post.

 

[Sharpend]

Justin, no one is trying to throw the book at you merely trying to ascertain your level of knowledge and competence, this is a public forum and the works you are asking about are quite comprehensive, so you must understand the we as the professionals must ensure that any advice offered is not misunderstood nor abused. 

What location are you in as it may be local to one of us, it may save you searching for an electrician. 

There is quite a bit of technical know how involved with what you need/want, some of which may only be obtainable from a site visit. 

If you are asking for options only then there are probably multiple solutions, each of which require different trench routes etc. 

How far is the bore pump from the shed?

Is it closer to either the shed or house? 

 

[justins]

Each grid square is approximately 30m x 30m. Single phase supply. As you can see, running everything from a cu in the house would mean a lot of cable

 

[Evans Electric]

As the Spoon said  , no cable sizes for various reasons  , I've sketched what the Spoon said which is what we'd all think I'd guess ,  just don't know the layout .

You are limited to what you can fit in a meter cupboard along with meter etc  but there should be no problem with what I've sketched .  

Not knowing the layout you're spark may elect to take Shed & Borehole cables back separately to  C/U .   

 

[Evans Electric]

You beat me with the layout ....now I'd suggest a cabinet at a strategic position  which would save cable lengths  and trenching . 

 

[Sidewinder]

To be honest, I'd put an external enclosure at the metering point feed that directly from the meter, and fit a board in there and feed the 3 supplies out independently.

If the design is done correctly then selectivity can be achieved and all should be fine.

 

[Sharpend]

I would concur with Sidey, as this would be my approach also, minimising your trench work.

so from the metering intake you’d place said external enclosure adjacent. 

Then dig a trench to shed. 

Then dig a trench to house. 

Along this trench you would dig a Sweeping bend to bore pump. 

Lay a black duct 50mm dia in trenches for each separate feed that’s 3 ducts for clarification. Make sure you put a suitable draw cord in each duct run for pulling cable through at later date. 

Trench should be a minimum of 500mm deep. Back fill with appropriate aggregate and sand, remember to place ‘electrical warning tape 100mm above duct. 

You will then have adequate trenching for your electrician to pull cables. 

Reminder all bends to be sweeping not tight. 

 

[Evans Electric]

Reminder all bends to be sweeping not tight. 

Eeez dun this before ! 

 

[Sidewinder]

To be honest I've always used a min of 75mm regardless, and no bends, straight runs with the duct bent into slow curves, and chambers at suitable points for pulling.

The duct really needs to be the right stuff too.

 

[Spoon]

Trench should be a minimum of 500mm deep.

I thought that the minimum depth was 600mm deep.

Happy to be corrected but 0.6 m is what I've seen in the regs.  Granted they are in section 705,  708 & 730.

Where does it state 500mm? 

 

[justins]

To be honest I've always used a min of 75mm regardless, and no bends, straight runs with the duct bent into slow curves, and chambers at suitable points for pulling.

The duct really needs to be the right stuff too.

Ducting for armoured cable? DNO don't even duct their cable unless under traffic area. Trenched for 3 phase and service cable a few years back. Only one small bit of duct where it went under field that would be ploughed? Yes, enclosing cabinet to make space for a distribution board was what I had thought originally. Maybe then cable to shed, cable to house and then cable from house cu to borehole.

 

[Sharpend]

I thought that the minimum depth was 600mm deep.

Happy to be corrected but 0.6 m is what I've seen in the regs.  Granted they are in section 705,  708 & 730.

Where does it state 500mm? 

Well oddly enough I always had a depth of 600mm however do I believe I was corrected on that by a technical helpline when I questioned it. 

??

maybe they got it from here? 

http://streetworks.org.uk/wp-content/uploads/2016/09/V1-Positioning-Colour-Coding-Issue-8.pdf

 

[justins]

Ground type Depth to top of cable / duct
Unmade, cultivated, or footpath  450mm
Driveway or road   600mm
Agricultural  1000mm

According to SSE