SWA Depth?

[Sparky83]

Hello all,

Hopefully just a quick question really, i need to quote to install some cable to go around the outside edge of a large rounded driveway, it will be sunk into the ground but at what depth?

Ive looked online but see different depths quote, some 450mm some 600mm and some completely different.

Just want to make sure be any work starts.

Thanks,

Sparky83

 

[Engineer54]

Do you honestly believe that the Reg's are the only regulatory body you are responsible to for following in your profession??

I'll tell you something else, YOU are responsible for that cable, so if your client makes a pig's ear of the burial, you will still be held responsible!! Don't believe me, ask anyone here!!
This is your installation, your responsible for the design, the installation, and the testing...

 

[pblec]

so go on then don't give standard depths because standard depths don't work what is the regulation depth for domestic burried cables

 

[Engineer54]

Yes, ...minimum 600mm direct buried, 450mm in an approved duct!!

EDIT .... Are you under some idea that domestic cable depths are not as stringent as for other locations?? Actually domestic garden depths are considered ''medium to high risk'' because of the likelihood and/or frequency of homeowners digging etc.

 

[pblec]

sorry thats not in the regs after all your signing a certificate to sy the instalation complies to BS7671 so surely you should know 522.8.10 ' be at a sufficient depth to avoid being damaged by any reasonable foreseable disturbances of the ground'

what reasonable or forseeable disturbances are my cables 300mm beloaw a lawn subject too?

 

[Des 56]

At least 2 spades depth seems reasonable and oft quoted
Now all you need is the measurement of a spade,if you dont know at least your cable is safe for the double dig spuds

2 spades in my measuring would be around 600mm

 

[Engineer54]

sorry thats not in the regs after all your signing a certificate to sy the instalation complies to BS7671 so surely you should know 522.8.10 ' be at a sufficient depth to avoid being damaged by any reasonable foreseable disturbances of the ground'

what reasonable or forseeable disturbances are my cables 300mm beloaw a lawn subject too?

Yep, a lawns gonna go a long way in protecting that cable!!!!

Wow!!!, ....As i say, just make dammed sure your indemnity insurance is bang upto date, ''Bang'' being a the operative word here!!!

 

[pblec]

thats my point you know the bit you still haven't answered whats the reasonable or forseable disturbance that cable is subject too which means it needs digging to 600mm where have you got 600mm from whats the regulation after all you've designed and installed this?

 

[Mark_Burgess]

pblec, the info you require is in GN1 Table 5.2.

Go and have a look.

 

[pblec]

GN 1 page 90 table 5.2 joist and stud notch and drill limits

you sure?

 

[Mark_Burgess]

GN 1, page 79.

is your book out of date?

 

[Silly Sausage]

Welcome, pblec, to hell, I mean the forum.

The fact that you've made a risk assessment of your installation shows you're taking it seriously and thinking about it.
But, the general consensus of opinion in your case is that you're not quite right, take it on board and have a re-think, no one's having a go.
This is a great forum where you will get lots of help and good advice, 99.99% of the guys on here are sound.

For sole traders for example, they're planning on doing an installation some way, what do you lot think, get loads of replies, comes out with a better install.

As far as this depth thing goes, whilst there is no specific reg about about depth of cables in the book, there are regs about protection against mechanical damage, someone will be along to quote reg numbers soon, which you need to take into consideration.

The book is a rats nest of cross references (I think) like a plate of spagetti, you can quote a certain reg about something and someone else will quote another from another section to stir things up!!!

Anyway, the beers kicking in now so I'm off.

Andy

 

[pblec]

cheers andy thanks for the tips, hopefuly someone will come back and post the reg. i beleive we work to a set of regulations so for someone to say you do it this way because we always do it that way is wrong granted every way people have said is safe but for someone to say my way isn't safe without backing it up is wrong.

Sorry mark was using internet to find it, i'm 100% domestic only so don't have GN1 or need it on my assessment and as your aware the GN is applicable to 17th so you should be able to quote the reg

 

[Engineer54]

thats my point you know the bit you still haven't answered whats the reasonable or forseable disturbance that cable is subject too which means it needs digging to 600mm where have you got 600mm from whats the regulation after all you've designed and installed this?

A standard electrical installation is normally considered to have a working life of at least 30 years. So unless you can reasonably say that, ...that lawn will not be disturbed or removed over that period of time, you have no argument!!! Over the course of that time period, the said property could have changed owners several times. I would doubt very much if any of the newer owners would have any idea of your cable routing. Hence we have termed safe cable burial depth's that we abide too .... More often than not, they Work, and work very well when adhered too!!!

 

[pblec]

ok granted in your opinion the lawn may get dug over, in the homeowners opinion he has no intention of digging over that lawn - i asked when selecting the route.

still not provided a regulation to cover it though, granted as i said your instalation is safe but my risk assesment for the reasonable and forseable still hasn't been proven wrong.

as i just said we've always done it that way isn't an argument.

 

[Mark_Burgess]

Well if you went ahead at your suggested depth and something tragic happened and traceability comes back to you its pick up the soap time.

However if you work to this and use warning tape you can at least defend yourself.