Lifting flagstones without cracking

TheChizler

Hoping to get some advice here on lifting a couple of sandstone flagstones in the front garden back home.

We're planning on installing an EV charger in a flower bed that is separated from the house by a path. The ramp is covered in 1.5 inch sandstone which I'm pretty sure is mortared down. We want to run an armoured cable to the charger under this ramp, we might get away with fitting it in the 18 mm grout gap, but I think we'll probably have to lift the paving. Has anyone any experience in removing paving like this without cracking it? The slabs are maybe 2.5 ' long as you can see, anything I can find through Google is dealing with much smaller slabs, I'd be afraid of the size of them making them more likely to crack.



If we manage to get one up without breaking it how should I stick it down again? A light cement and sand mix? What kind of grout would normally be recommended? Any tips welcome.

Lumen

TheChizler wrote: »

We want to run an armoured cable to the charger under this ramp, we might get away with fitting it in the 18 mm grout gap

From what I understand of the electrical regs (NT101 National Wiring Regulations), you have two choices:

1. Run it along the surface, clearly visible.

2. Bury it in 700mm trench, comprising from bottom up 100mm sifted soil or sand, armoured cable, 150mm sifted soil or sand, cable tile, warning tape, 450mm backfill.

You can't just run it under the slab or hide it in the grout.

So if you're going to do it legally, you're going to need to remove pretty much all of those slabs and get digging.

As to what it'll take to lift them, it depends on what's holding them down. They may just be sitting on dry sand/cement mix, in which case just lever them up carefully.

listermint

tbh, id be surprised if you crack them. Its not hugely likely.

Take your time lifting with a spade at the edge, they should just come straight up.

TheChizler

Lumen wrote: »

From what I understand of the electrical regs (NT101 National Wiring Regulations), you have two choices:

1. Run it along the surface, clearly visible.

2. Bury it in 700mm trench, comprising from bottom up 100mm sifted soil or sand, armoured cable, 150mm sifted soil or sand, cable tile, warning tape, 450mm backfill.

You can't just run it under the slab or hide it in the grout.

So if you're going to do it legally, you're going to need to remove pretty much all of those slabs and get digging.

As to what it'll take to lift them, it depends on what's holding them down. They may just be sitting on dry sand/cement mix, in which case just lever them up carefully.

Thanks for the response!

Hmm, I was aware of that for long runs through soil, didn't realise it could apply even for short runs under something that wasn't likely to be disturbed. There's an old concrete path under the stone, I was planning on knocking out a shallow channel and laying the power cable (and shielded data cable in case they ever upgrade) in a flexible conduit. I don't think it's a runner if we have to go as deep as the path is wide almost.

There's another route I could take where I could pin the cable to the underside of some steps at the top of the picture but it's about 5 times the length and wouldn't be easily possible to make it tidy inside the house.

The electrician who'll be doing the final connections and signing off will be coming in the next few days hopefully to take a look at it so I'll get his opinion then.

I've given them a tug to see if they would shift but didn't want to try properly until I was committing to lifting them, hopefully there's no adhesion as you say.

TheChizler

listermint wrote: »

tbh, id be surprised if you crack them. Its not hugely likely.

Take your time lifting with a spade at the edge, they should just come straight up.

Cheers, that's reassuring. I'll see what our sparks says and go from there!

Calahonda52

Lumen wrote: »

From what I understand of the electrical regs (NT101 National Wiring Regulations), you have two choices:

1. Run it along the surface, clearly visible.

2. Bury it in 700mm trench, comprising from bottom up 100mm sifted soil or sand, armoured cable, 150mm sifted soil or sand, cable tile, warning tape, 450mm backfill.

You can't just run it under the slab or hide it in the grout.

So if you're going to do it legally, you're going to need to remove pretty much all of those slabs and get digging.

As to what it'll take to lift them, it depends on what's holding them down. They may just be sitting on dry sand/cement mix, in which case just lever them up carefully.

L, you sure about this: am looking at table 52B on page 84 of the 4th Edition 2008 version of ET 101 printed in 2016 and there are much reduced depths for domestic paths:
SWA or NYCY in soil 450 mm
In high impact resistant ducting: 250 mm.. must be red or concrete

Rows Grower

TheChizler wrote: »

Hoping to get some advice here on lifting a couple of sandstone flagstones in the front garden back home.

We're planning on installing an EV charger in a flower bed that is separated from the house by a path. The ramp is covered in 1.5 inch sandstone which I'm pretty sure is mortared down. We want to run an armoured cable to the charger under this ramp, we might get away with fitting it in the 18 mm grout gap, but I think we'll probably have to lift the paving. Has anyone any experience in removing paving like this without cracking it? The slabs are maybe 2.5 ' long as you can see, anything I can find through Google is dealing with much smaller slabs, I'd be afraid of the size of them making them more likely to crack.



If we manage to get one up without breaking it how should I stick it down again? A light cement and sand mix? What kind of grout would normally be recommended? Any tips welcome.

See if you can get one of the ones at the very start or finish of the path up with a bolster and hammer but take your time, don't go at it all gung ho.

Once you get one lifted you should be able to lift the rest fairly handy and you'll get more confident with each one.

If you can't start at one of the edges pick the smallest one and smash it with a lump hammer and then work away under the rest with the bolster.

Stick them back down with sand and cement or rapid set tile adhesive and grout the joints with dry sand and cement 4 to 1 mix or just fine sand.

Lumen

Calahonda52 wrote: »

L, you sure about this: am looking at table 52B on page 84 of the 4th Edition 2008 version of ET 101 printed in 2016 and there are much reduced depths for domestic paths:
SWA or NYCY in soil 450 mm
In high impact resistant ducting: 250 mm.. must be red or concrete

The exact details I posted are from a photo of a diagram sent to me, but I don't have further details.

Obviously some bureaucratic genius decided that it would do us plebs no good to understand what the regs are, because none of the PDFs are public.

Anyway, if I interpret what you've posted correctly, it's 250mm depth when the cable is in red-coloured impact-resistant ducting like this:



OR 450mm depth without ducting.

Is that right?

I don't really understand "SWA or NYCY". SWA is armoured and NYCY isn't, right? So how can they be interchangeable?

TheChizler

Rows Grower wrote: »

See if you can get one of the ones at the very start or finish of the path up with a bolster and hammer but take your time, don't go at it all gung ho.

Once you get one lifted you should be able to lift the rest fairly handy and you'll get more confident with each one.

If you can't start at one of the edges pick the smallest one and smash it with a lump hammer and then work away under the rest with the bolster.

Stick them back down with sand and cement or rapid set tile adhesive and grout the joints with dry sand and cement 4 to 1 mix or just fine sand.

Forgot to mention it'll be perpendicular across the path so hopefully it'll just be two stones. I'll have to dig out the bed to anchor the post for the charger so should have good access from the edge anyway.

Should I wet the grout or will it just pull in moisture from the surroundings?

Thanks for the advice!

TheChizler

Calahonda52 wrote: »

L, you sure about this: am looking at table 52B on page 84 of the 4th Edition 2008 version of ET 101 printed in 2016 and there are much reduced depths for domestic paths:
SWA or NYCY in soil 450 mm
In high impact resistant ducting: 250 mm.. must be red or concrete

I'll take 250mm over 700! I'll still check with the sparks before doing anything as I still need him to sign off on everything at the end of the day. Any pipe as long as it's red?

It's an awful lot of work for such a short run of cable but I want it to look and be right. Probably won't do any drilling or kangaing myself as he'd do a quicker job but I just want to prep as much as I can and more importantly limit the scope for the run of cable. We've had electricians in the past drill through a brand new kitchen cabinet because they werent bothered to hide the cable, I'd prefer to keep what's tacked on to the outside of the house to a minimum.

Rows Grower

TheChizler wrote: »

Forgot to mention it'll be perpendicular across the path so hopefully it'll just be two stones. I'll have to dig out the bed to anchor the post for the charger so should have good access from the edge anyway.

Should I wet the grout or will it just pull in moisture from the surroundings?

Thanks for the advice!

No need to wet it, brush it in dry and let it settle and it will go rock hard.

At worse it might sink a smidgen when it settles, if it does just brush a little more over it again a week later but it should be fine.

Rows Grower

TheChizler wrote: »

I'll take 250mm over 700! I'll still check with the sparks before doing anything as I still need him to sign off on everything at the end of the day. Any pipe as long as it's red?

It's an awful lot of work for such a short run of cable but I want it to look and be right.

The red pipe is what is used when running a mains cable to an ESB meter, probably a bit OTT for the job you are doing.

It's a standard pipe that will withstand a fair bit of digging around/over it, it's red to warn anyone that might be digging in years to come of the danger within.

By right you should also lay red and white plastic over it.

Purgative

Hi OP


I'm no expert but I'll just let you know what we did about 18 months ago.


We needed a connection out the back of the house. One of problems we had was that all the other services come off the back of the house. Its quite an old house and the electricity is in whatever they used at the time - certainly no sort of conduit.


The electrician just said lay 4" drainage pipe as best you can without getting to close to mains or soil pipes. Its strong and easy to handle.


All the best.

Calahonda52

Lumen wrote: »

The exact details I posted are from a photo of a diagram sent to me, but I don't have further details.

Obviously some bureaucratic genius decided that it would do us plebs no good to understand what the regs are, because none of the PDFs are public.

Anyway, if I interpret what you've posted correctly, it's 250mm depth when the cable is in red-coloured impact-resistant ducting like this:



OR 450mm depth without ducting.

Is that right?

I don't really understand "SWA or NYCY". SWA is armoured and NYCY isn't, right? So how can they be interchangeable?

No, I will scan and post the page later

Calahonda52

Purgative wrote: »

Hi OP


I'm no expert but I'll just let you know what we did about 18 months ago.


We needed a connection out the back of the house. One of problems we had was that all the other services come off the back of the house. Its quite an old house and the electricity is in whatever they used at the time - certainly no sort of conduit.


The electrician just said lay 4" drainage pipe as best you can without getting to close to mains or soil pipes. Its strong and easy to handle.


All the best.

May not pass the high impact test and not being red is dangerous

Purgative

Calahonda52 wrote: »

May not pass the high impact test and not being red is dangerous

Fair comment, but the whole mains feed is not red. The ESB have seen it and reconnected it*.



We did the best that we reasonably could.










* When we had a pole moved 10 or so years ago.

Calahonda52

Not arguing about the past at all, just pointing out for others the current regs, nothing more.

listermint

Purgative wrote: »

Fair comment, but the whole mains feed is not red. The ESB have seen it and reconnected it*.



We did the best that we reasonably could.










* When we had a pole moved 10 or so years ago.

They should have asked for a Red Hockey Stick to be put in, I had to do this exact thing when i got a meter box moved.

Red Hockey stick with a pull wire through it so they could fish the Mains feed in.

The hockey sticks are cheap - can get them in Goodwins.

TheChizler

Eventually got someone in to do this as it would probably take me 12 years and I'd never be satified with the result. Electrician was happy to have armoured cable just under the surface, no idea if they used red tubing to protect it or not as it was done before I got there to take a few pictures. Flagstones popped off without an issue apparently. The new grout colour is slightly different, I'm hoping it'll darken to match over time. Also I'm probably the only person who'll ever notice.

Tidy result in the end!