Water pipe and electricity cable in duct to carport/garage

[AliG]

Hi,

 

We have put a duct under our foundations to carry electricity cables under the house and then across to the carport.

 

Can we push 15mm pipe through this to have an outside tap there also.

 

I know you cannot mix them on the supply side but am not sure what the rules are once the are into the house.

 

If they cannot be in the same duct once into the garden, could they be in the same duct then split once it is out from under the foundations?

 

Thanks

[markc]

It may be frowned on but I don’t know of anything that says you can’t have water and cable in the same duct especially as it’s on your side of the supply.

Both in the same trench is common and the trench will drain whereas a duct probably won’t (assuming ends turn up). 

[Mr Punter]

It is very bad form to feed a service through the wrong duct type but it if that is what you have then you need to be pragmatic.

 

If you have not ducted up to the car port, do this with the correct ducts.

 

I assume the one your have is electric duct and the cable is SWA?

[AliG]

All we have at the moment is a duct under the foundation.

 

It was intended initially for electricity, but the outside tap has not been put in yet and the best place for it is actually the carport.

 

 

[ProDave]

I will tell you a story about a new build not far from here.

 

SSE came first and connected the power, making a road crossing and installing a bit of black ducting under the road probably about 75mm diameter.

 

Next along came Scottish water, who fed their water pipe through the same black duct to save digging the road up.

 

And you guessed it, when Open Reach came along, guess where the telephone cable went......

[HughF]

I ended up putting 10mm swa and 16mm mlcp down the same 40mm duct. After the trench was backfilled SWMBO insisted on a water supply to the shed.

 

It was bloody hard work pulling them through. I thought we weren’t going to manage it actually. There were 3x 90s to go round.

[Temp]

How big is the duct? If big enough could you push another duct through it for the water or electric just to give a bit more protection/separation.

[AliG]

Thanks guys. In the end we just put the outside tap on the house so we didn’t have to argue about it

[markharro]

Hi @AliGmaybe you can help me on a related theme. I have two things I am wrestling with atm. I have scheduled a lead replacement new water instal from SW. The engineer said it would be 25mm bore. It looks like the supply pipe is on the opposite side of the road to us. My pal (a BP engineer) mentioned that he would normally expect a 28mm or 32mm bore for decent water pressure. That's the first issue. How do I know what to specify?

The second thing is that I am deciding on ducting under our slab. We want an outdoor tap on the house wall (about 7/8 metres I guess away from where the water will enter the utility room). Options for this are to tee it from the supply outside at our boundary and take it completely outdoors to avoid any plumbing running through the house or tee off at the utility room. That would then need a hole through our external wall to the tap.

We want to have another outdoor tap this time in the back garden. I had thought that the best thing for this was a tee from the utility room and down through the slab and then right across the width of the slab underneath to take us to the back garden. But another way would be to tee off where the supply comes in off the street in the front garden and then take the connection round a long loop right around the perimeter of the house to the back garden. 

I have asked our architect about what is best with all of this but he says these are services issues that he cant properly comment on!

[AliG]

House supply is normally either 25 or 32mm.

 

Larger pipes allow more flow, but actually can reduce the pressure. I am not really an expert on this.

 

We have 32mm the pressure is not great, but flow is fine. I think you are free to connect 32 or 25mm to the water main as you will be installing that pipe. TBH the main issue with pressure seems to be SW turning it down to reduce leaks.

 

As for the outside taps I think it is probably better to keep the pipework inside the house as you can always access it in future. I would tee off at he utility room, 7-8m is not far at all and you can then have the isolator in the utility room. Wouldn't worry at all about a small hole in the wall. It also means most of the pipework is in the insulated building. I think the work to put it in the ground will be more expensive.

 

I am not sure about the back garden tap, it sounds like you want it away from the house? The more pipe you have outside the more risk you have of it freezing, I guess if you want it, it would be better to take it under the slab as it reduces the amount of pipework exposed above ground.