Best JB to bury - driveway lights

[richo106]

Hi

I am looking to install some driveway up lights on my new drive way, either side of my drive is grass/gravel (soft dig)

I have spoke to a couple sparky mates and they have done it with galv conduit t boxes, wagos and magic gel (or similar) with gaskets/box lids. SWA between the boxes and flex out to driveway. Then bury these boxes to the side of the driveway so they aren’t on show, I know not ideal but no where else to put JB’s

My question is, is there a better way to do this? What’s the best thing to bury? Wiska box? Galv conduit box?

Any advice/ information greatly appreciated

Many Thanks

 

[davesparks]

Thank you for the replies, I am going to look for a resin T joint.

Could I just fill wiska box’s with resin? And use wago connectors. As there will be 2 x SWA’s and flex

Thanks again

There would be problems with using a wiska box in this way.
-The SWA gland which forms and essential part of the earth connection is outside the box and so does not get encapsulated in the resin, in a proper underground joint this connection is made by a different method and is contained within the joint.
-you would need to purchase addition parts to make the earthing connection to the SWA.
-you would need to work out how much resin is required and purchase it separately.
-wiska boxes are the wrong shape to get a proper resin fill without getting voids/air bubbles in the resin, proper underground joints have a smooth round shape and a few taps with the handle of a screwdriver is normally enough to encourage all the air bubbles up to the surface.

Magic Gel Pack (420g/ml) - IP68 | Wiska (MPSG420W)

That's not resin, that's gel, as per its name.

 

[davesparks]

1. Safety – 12 volts is inherently safe for children and pets

No it isn't, it would be safer if installed correctly, but not inherently safe. Some pets will be killed by a 12V shock.

1. Easier installation of cables in borders and planting – flexible cables to spike spotlights can be several times longer than to 240 volt garden lights and you can move them around more easily.

I'm not following your logic here, how does voltage change how long a cable can be?

1. A better range of lamps to choose from which are brighter, whiter, more efficient and longer lasting than their 240 volt cousins. Some 12 volt lamps are twice as efficient as their 240 volt equivalents.

I assume we're talking LED lamps here as that's pretty much all that is available these days so I don't see how they can be brighter and whiter when LEDs have a specific colour temperature and will be as bright as you choose regardless of which supply voltage they are for.
Is there really a better range of 12V LED lamps than 240V?

1. If you have an accident with a low voltage cable it is usually easier to fix.

Is it? Surely it's going to need a waterproof or buryable joint regardless of what voltage the cable is operating at?

1. Low voltage transformers and power supplies absorb transients such as those caused when a lamp blows and are, to a degree, tolerant of earth currents arising from a bit of damp in light fittings. A little bit of dampness might not affect a 12 volt circuit but it could render a 240 volt circuit unusable.

How is an ELV supply tolerant of earth currents, or more to the point how is an earth current due to damp going to occur in the first place? Surely any ELV supply used would be SELV which would make your comment about earth currents somewhat nonsensical wouldn't it?

You can use flexible cables, HI-Tuffs of similar length for their installation rather than armoured, and you don’t need to bury the cables approximately 600mm, as you do with LV installations.

I'd have to check the book but I thought BS7671 had a blanket requirement for all buried cables and didn't have different requirements for buried ELV cables?

 

[mainline]

How does using elv change the type of buried connection.

ELV can have plug and play type connections and doesn't require the effort that swa would.

 

[mainline]

No it isn't, it would be safer if installed correctly, but not inherently safe. Some pets will be killed by a 12V shock.

What pet would that be ?

I assume we're talking LED lamps here as that's pretty much all that is available these days so I don't see how they can be brighter and whiter when LEDs have a specific colour temperature and will be as bright as you choose regardless of which supply voltage they are for.
Is there really a better range of 12V LED lamps than 240V?

I think they were comparing with non led lamps, but the post was quite old, I didn't realise until after

Is it? Surely it's going to need a waterproof or buryable joint regardless of what voltage the cable is operating at?

It's more the range and types of boxes etc for elv that makes connections easier.

How is an ELV supply tolerant of earth currents, or more to the point how is an earth current due to damp going to occur in the first place? Surely any ELV supply used would be SELV which would make your comment about earth currents somewhat nonsensical wouldn't it?

It wasn't my comment, but I think you know what was meant by it.
And it has to be more tolerant if it can't occur.

I'd have to check the book but I thought BS7671 had a blanket requirement for all buried cables and didn't have different requirements for buried ELV cables?

As already said, it was a paste from a site which hasn't a very good explanation

 

[davesparks]

ELV can have plug and play type connections and doesn't require the effort that swa would.

The requirements for buried cables don't change with voltage, see 522.8.10

 

[plugsandsparks]

This is my experience having had the unfortunate job of doing well into 400 garden lights, and some never do's - its a personal position not related to any regulation / BS Standard.

1. I simply dont bury a final cct at 240VAC protected by RCD at the main board.
2. I come out of the DB and distribute multicore SWA to GRP junction box mounted on posts or side of building.
3. I then drop down cores, e.g. 12 core to 7 core to 4 core as i move away from the DB further into the garden, this allows control of zones of garden at the 240V level.
4. I install specific Tridonic outdoor drivers in the same GRP above ground box per zone.
5. I then star out from GRp box to individual lights and make connection in the GRP box using din mounted terminal blocks
6. The lights are CC usually 350mA industry standard lights.
7. Where i have to joint cables i use crimps and 2 layers of adhesive heat shrink sleave or if there are some multiple joints i have used wiska boxes, drilled a small hole in the very top and used bullet swajoint resin, warmed up under the bonnet of the vehicle, lol.

Benefits are:
1. one dodgy light or joint will not take out the RCD and subsequently a good number of lights as the drivers handle the fault and it just affects the zone the driver is connected to.
2, fault finding is easy as you can disconnect individual lights at the GRP Box and get the zone back up and running minus the dodgy light.
3. When the gardeners finally chop though the cable, reduced impact as the driver handles both the short cct and eventual open cct, again just that zone is affected.

 

[mainline]

This is my experience having had the unfortunate job of doing well into 400 garden lights, and some never do's - its a personal position not related to any regulation / BS Standard.

1. I simply dont bury a final cct at 240VAC protected by RCD at the main board.
2. I come out of the DB and distribute multicore SWA to GRP junction box mounted on posts or side of building.
3. I then drop down cores, e.g. 12 core to 7 core to 4 core as i move away from the DB further into the garden, this allows control of zones of garden at the 240V level.
4. I install specific Tridonic outdoor drivers in the same GRP above ground box per zone.
5. I then star out from GRp box to individual lights and make connection in the GRP box using din mounted terminal blocks
6. The lights are CC usually 350mA industry standard lights.
7. Where i have to joint cables i use crimps and 2 layers of adhesive heat shrink sleave or if there are some multiple joints i have used wiska boxes, drilled a small hole in the very top and used bullet swajoint resin, warmed up under the bonnet of the vehicle, lol.

Benefits are:
1. one dodgy light or joint will not take out the RCD and subsequently a good number of lights as the drivers handle the fault and it just affects the zone the driver is connected to.
2, fault finding is easy as you can disconnect individual lights at the GRP Box and get the zone back up and running minus the dodgy light.
3. When the gardeners finally chop though the cable, reduced impact as the driver handles both the short cct and eventual open cct, again just that zone is affected.

The OP is only wanting some buried driveway 240v lights and all i asked was had he considered elv lighting and it's turned into a drama

 

[davesparks]

The OP is only wanting some buried driveway 240v lights and all i asked was had he considered elv lighting and it's turned into a drama

Actually the OP asked what type of joint is best for burial, they didn't ask for advice on type of light fitting or operating voltage.

 

[mainline]

Actually the OP asked what type of joint is best for burial, they didn't ask for advice on type of light fitting or operating voltage.

He also said :

My question is, is there a better way to do this?

Any advice/ information greatly appreciated

 

[plugsandsparks]

TBH - Garden lights = a lot of pain for little gain, Mrs P&S just got some solar ones and i hid in the office until the attraction of looking at the garden at night wore off,

 

[Pretty Mouth]

The requirements for buried cables don't change with voltage, see 522.8.10

There was an intended change for the 18th edition, exempting SELV cables from 522.8.10. Never made it into the final print though. The page on the IET site seems to be gone now, but I saved a copy. I think it would have been a good thing.

 

[davesparks]

There was an intended change for the 18th edition, exempting SELV cables from 522.8.10. Never made it into the final print though. The page on the IET site seems to be gone now, but I saved a copy. I think it would have been a good thing.

Why would it be a good thing?

Underground cables are all exposed to the same risk of damage regardless of voltage.

Yes the risk to a person from electric shock is reduced with ELV, but that is only one of the considerations when burying cables.

 

[mainline]

There was an intended change for the 18th edition, exempting SELV cables from 522.8.10. Never made it into the final print though. The page on the IET site seems to be gone now, but I saved a copy. I think it would have been a good thing.

Selection and erection of wiring systems - Chapter 52 - Wiring Regulations Information

Chapter 52 Selection and erection of wiring systems Regulation 521.11.201 which give requirements for the methods of support of wiring systems in escape routes, has been replaced by a new Regulation 521.10.202. This is a significant change. Regulation 521.10.202 requires cables to be adequately...

www.wiring-regulations.co.uk

 

[mainline]

Why would it be a good thing?

Underground cables are all exposed to the same risk of damage regardless of voltage.

Yes the risk to a person from electric shock is reduced with ELV, but that is only one of the considerations when burying cables.

It is blatantly obvious that ELV is far safer than LV that's a fact, although you did say some pets can be killed by 12v, but you didn't reply when i asked what sort of pet ? So I can only guess it to be some sort of slug, must be a long day taking one for a walk )

There are ready-made hubs and joint boxes for ELV which make especially for non-buried cables a lot easier to install and maintain.

There is also the nuisance tripping aspect of ELV to take into account compared to a mains supply, especially with a failure of a rcd.

There maybe the same risk of damage to the cables, but the effects of ELV are far less likely to cause any drama compared to mains derived ones.

 

[Pretty Mouth]

Why would it be a good thing?

Underground cables are all exposed to the same risk of damage regardless of voltage.

Yes the risk to a person from electric shock is reduced with ELV, but that is only one of the considerations when burying cables.

Firstly, cables buried at pretty much any reasonable depth can be damaged. I have personally dug by hand foundations to a depth of 6ft.

Getting the cables deep enough to 'comply' with 52.8.10 is labour intensive, and often impossible. In my experience, for garden lighting and so on, they're rarely installed more than a few inches down. Basically, it's a regulation that gets ignored because it's unrealistic to achieve.

Allowing SELV cables to be run at any depth gives a negligible shock risk should they be damaged, does not cause tripping further upstream, and, in my experience, cables such as H07RNF are much easier to repair than SWA.

The regs permit a similar exception for selv cables run <50mm deep in walls, through walls constructed of metal parts, and where concealed below floors/ceilings. To me, it seems sensible to allow similar for cables buried in th ground