PVC,PVC joined to SWA in an underground joint

[Pete999]

Went to look at at a job with a mate of mine who is a Sparky, it's in a Farm house more to the point it's in the Garden.

The owner has two garden offices an old one being demolished at a later date I'll call that shed 1 and next to it is his new shed called shed2, get the picture?

He has had the shed 2 rewired with PVC PVC and a SWA has been connected to the new CU left coiled up outside so no juice in there yet. Now he was told by the sparky who, according to Farmer Giles has mysteriously become unavailable, I know not why that it would be OK to join the PVC PVC 6mm feeding shed 1 with the 6mm SWA feeding shed 2 in a resin filled UG joint, with me so far? He was not a happy chappy when I told him the SWA should be taken into the house and terminated correctly in a CU which has plenty of capacity.

His face went kind of a red colour and his whiskers bristled got accused of hiking the price up, now before I tell my mate to walk away, is there a way of joining these two cables UG? not ever seen a method so I thought I would ask, my preference would be to run the SWA as described earlier, but it;s not my job just asking out of curiosity.

 

[Octopus]

Do it properly, do it once... or walk away....

 

[mechelec]

Yep use one of these Branch Resin Joint Kit - SWA
i can't see a problem if it's been done correctly and all calculations for load, Ze, volt drop etc are ok

 

[davesparks]

Is this pvc/pvc cable underground or above ground?
If the pvc/pvc cable has all the necessary mechanical and other protections for the conditions it is in then I see no issue

 

[Pete999]

Is this pvc/pvc cable underground or above ground?
If the pvc/pvc cable has all the necessary mechanical and other protections for the conditions it is in then I see no issue

UG in PVC conduit

 

[Dave OCD]

If the pvc end of the joint could be cut so that the conduit/ducting goes in to it and assuming it can still be sealed properly for the resin pouring then I'd say that would be an acceptable method. Would need RCD protection at 'source' though in case of accidental future damage to the 6242y in the PVC conduit.

 

[davesparks]

UG in PVC conduit

Then I would say it is not acceptable as pvc/pvc cable underground is not allowed without an earthed metallic protection

 

[Dave OCD]

Is there a reg to back that up clearly Dave ? I know it's a little vulnerable but if at a sensible depth in conduit backed up by a 30ma RCD with the joint position clearly marked it should be fine ?

 

[Andy78]

Is there a reg to back that up clearly Dave ? I know it's a little vulnerable but if at a sensible depth in conduit backed up by a 30ma RCD with the joint position clearly marked it should be fine ?

I don't think the reg that requires earthed metal coverings for buried cables makes an exception where RCD protection for the cable is employed. It's not been stated that an RCD is present in this case anyway.

 

[Octopus]

Is it me or is it just bad practice to bury T&E and then joint it underground to SWA?

How long is the run, end to end?

 

[jackhammerJIM]

Is it me or is it just bad practice to bury T&E and then joint it underground to SWA?

How long is the run, end to end?

I agree . He may aswell have not bothered with the swa and joined another twin and earth .

 

[Darkwood]

You can't possibly comply as is, sounds like you been fed some of his very own farmed bull'--- by Farmer Giles and he has tried to save a few pounds...

Where does this existing PVC/PVC run and has it any mechanical protection if needed?

 

[Pete999]

I don't think the reg that requires earthed metal coverings for buried cables makes an exception where RCD protection for the cable is employed. It's not been stated that an RCD is present in this case anyway.

RCD present

 

[davesparks]

Is there a reg to back that up clearly Dave ? I know it's a little vulnerable but if at a sensible depth in conduit backed up by a 30ma RCD with the joint position clearly marked it should be fine ?

No regs to hand, but a little bit of common sense says RCDs are irrelevant in this situation and PVC/PVC cables aren't acceptable underground.
Maybe if it had been specified as to what type of cable it is then the answer may be different, but to just say PVC/PVC it could be flex or T&E which certainly shouldn't be underground, or NYY-J/hi tuff etc which may be acceptable

 

[Dave OCD]

Yet I'm sure that it was considered perfectly acceptable for a long time to run 'normal' T&E underground as long as it was in continuous ducting - obviously times [and regulations] change though.

 

[telectrix]

is an underground joint smuggled weed? :8:

 

[davesparks]

Yet I'm sure that it was considered perfectly acceptable for a long time to run 'normal' T&E underground as long as it was in continuous ducting - obviously times [and regulations] change though.

Considered acceptable by whom?

 

[Pete999]

Is it me or is it just bad practice to bury T&E and then joint it underground to SWA?

How long is the run, end to end?

Certainly is IMO was just asking out of curiosity if anyone had heard of way of doing I would go for what you said earlier "do it right or walk"

 

[Pete999]

is an underground joint smuggled weed? :8:

Could be mate this trade has gone to pot anyway

 

[Dave OCD]

Considered acceptable by whom?

Me once or twice, each job is different and I've run T&E in ducting where it's been concreted/brick paved or had tarmac over the top- realistically I can't see a problem and they've all been backed up at source by 30ma RCDs.

 

[Barry White]

is an underground joint smuggled weed? :8:

Certainly uses resin

 

[GETWIRED]

IMO bad practice... And in reality, could you be bothered faffing about trying to make an underground swa to pvc/pvc resin joint comply? - Emphasis on the trying - I couldnt. Tell the tight arse to get his hand in his pocket and do it properly lol, farmers are loaded anyway!

 

[Octopus]

The

Me once or twice, each job is different and I've run T&E in ducting where it's been concreted/brick paved or had tarmac over the top- realistically I can't see a problem and they've all been backed up at source by 30ma RCDs.

And I bet yours didn't have a join in it!

 

[Dave OCD]

The

And I bet yours didn't have a join in it!

No that's a different thing altogether.

 

[HandySparks]

Yet I'm sure that it was considered perfectly acceptable for a long time to run 'normal' T&E underground as long as it was in continuous ducting - obviously times [and regulations] change though.

Considered acceptable by whom?

Thought I'd look this one up.

Looks as if the IEE considered T&E acceptable in underground ducting.

15th edition, amended to Jan 1983.

523-24 Cables to be installed in underground ducts, conduits or pipes shall be of a type incorporating a sheath and/or armour suitably resistant to any mechanical damage likely to be caused during drawing in.
(The word 'conduits' appears to be deleted at a later revision.)

Appendix 10, Notes on the selection of types of cable... , Table 10A, Applications of cables for fixed wiring. This lists one of the applications of flat pvc insulated and sheathed as 'Underground in conduits and pipes'.

There's a general note below the table: 'The use of cable covers (preferably conforming to BS 2484) or equivalent mechanical protection is desirable for all underground cables which might be subsequently disturbed'.


Note that the current regs allow for the use of non-armoured cables in suitable duct underground:
522.8.10 Except where installed in a conduit or duct which provides equivalent protection against mechanical damage, a cable buried in the ground shall incorporate an earthed armour or metal sheath or both, suitable for use as a protective conductor.....

Interestingly, there's no requirement for the 'equivalent protection' to comprise earthed metal. So that a sufficiently robust plastic duct would comply.


I'm not suggesting that the OP's example comprises 'equivalent mechanical protection'.


Personally, my default cable for underground use (whether in a duct or not) is SWA.

 

[Deleted member 9648]

Then I would say it is not acceptable as pvc/pvc cable underground is not allowed without an earthed metallic protection

Don't have the current regs to hand....only the BRB. But unarmoured cables in conduit or duct underground is shown as an installation method.
While we may not like it....it might be hard to convince a farmer he needs to part with additional cash without giving a valid reason such as it does not comply with regulations.

 

[Deleted member 9648]

Then I would say it is not acceptable as pvc/pvc cable underground is not allowed without an earthed metallic protection

Apparently it is.

 

[Dave OCD]

Apparently it is.

I won't say I told you so. :biggrin:

 

[ipf]

I won't say I told you so. :biggrin:

Lob some chockys in the duct, then.

 

[Dave OCD]

Lob some chockys in the duct, then.

Eh, what are you on about ?

 

[Martin Kerr]

I think he meant straight thru's with heat shrink

 

[ruston]

By the time you buy a 'suitable' duct it would probably be just as economical to use armour with the added peace of mind that it would give.

 

[Andy78]

Don't have the current regs to hand....only the BRB. But unarmoured cables in conduit or duct underground is shown as an installation method.
While we may not like it....it might be hard to convince a farmer he needs to part with additional cash without giving a valid reason such as it does not comply with regulations.

If it's method number 71 then the BRB was the last appearance as a listed method for CCC calculations.

 

[ipf]

Eh, what are you on about ?

Sorry! I know nothing :book:...hardly.

 

[ruston]

Sorry! I know nothing :book:...hardly.

I knew I knew you from somewhere.

 

[Dave OCD]

Sorry! I know nothing :book:...hardly.

Well I don't know either.

 

[ipf]

I knew I knew you from somewhere.

You got any insulation tape, Rus.....?

 

[ruston]

Loads all colours , not waterproof though.:vanish:

 

[Pete999]

Loads all colours , not waterproof though.:vanish:

It's getting silly boys lol

 

[djelectric]

I was taught at college that when designing circuits never to rely on an RCD operating in the event of a fault. I know its rare but RCDs can fail and if you had adequate mechanical protection you would have that extra layer and peace of mind.