Underground cable layed in duct - plain 2+E or SWA ?

Girl Geraldine

I have installed a pump chamber on the outlet of my septic tank which obviously needs power supply. So for this I have laid a 125mm red ESB spec rigid duct from the house for a distance of about 30m across the yard and grass towards the chamber. Cover to the duct is 450-600mm. The duct terminates in an earthed micro-pillar. Into the micropillar I will install 2x 16A blue sockets, the pump will be plugged into one of these, with the pump flex exiting the micropillar via a 50mm duct leading into the underground pump chamber. Where the 125mm duct turns up at the wall of the house, I have it capped off in a blank which I will drill 25mm to allow the cable through, and from there the cable will be ducted up into the eaves in a false "rainwater downpipe".

Main question is this - in a ducted arragement like this, should I be putting in a plain 2+E PVC cable, or a SWA cable?

Also, obviously it'll need to be on its own RCBO, but is a separate switched fused connection unit required on the wall before the cable leaves the house? Or can it run out straight from the RCBO?

kirk.

Use SWA if it's underground regardless of ducting

I wired plenty of treatment units , there was never any isolators or fused spurs at the house

The usual pump setup if I recall is pump and float switch in the treatment unit pumping direct to the soakaway.

Girl Geraldine

OK so. SWA it is then.

The pump is 350W, cable run is about 35m overall. With 10A RCBO, would 1.5mm 2 core SWA cable be big enough?

Would it be necessary to have a switch or isolator in the micropillar along side the pump? I would have thought not since the pump can be isolated by simply plugging it out of the 16A socket.

The pump has a float switch on it. The pump came with a regular 13A plug but I'm cutting that off and replacing it with a 16A plug.

kirk.

IP66 13a socket or switched spur in micropillar for pump , use whatever fusing comes with pump 3 or 5amp etc.

What's the second socket for , is there aerator in the tank?

2.5 SWA

Don't you need certs for all this and a REC , thought DIY was gone with all this type of equipment now for certification , conformity etc. ?

Only a REC can connect at board legally

Girl Geraldine

OK thank you. I will use the IP66 13A sockets. Is this so as to have a fuse on the pump, as well as the RCBO?

The second socket isn't for anything in particular, just a spare just in case anything needed to be plugged in out there. Better looking at it than for it and it is as easy to put in a double as a single.

😉😉

monseiur

125mm duct seems an overkill, a roll of 50mm will do, you'll save over €90.00 and have 20m. left over for the next job. Roll out duct and leave for a few days to straighten out, cut to required lenght. Tie a piece of aeroboard to string and suck thru duct with hoover, use string to pull 6mm nylon rope thru', pull SWA cable thru' with nylon rope. Do all this above ground then drop into trench and cover with 300mm soil, (assuming trench is over 600mm deep) lay ''buried electric cable'' warning tape in trench and back fill - job done

kirk.

https://www.boards.ie/discussion/comment/120085155#Comment_120085155

Doe that work well sucking the aeroboard with a hoover?

What distance would it work over

monseiur

https://www.boards.ie/discussion/comment/120085226#Comment_120085226

It worked for me over 33 metres, just ensure that the joint where the hoover hose is connected to duct is well sealed with duct tape and the aeroboard needs to be a fairly tight fit but free enough to pass thru duct. The straighter the duct the easier it is for the aeroboard to pass thru, hence the reason for rolling it out and leaving it for a few days. These industrial hoovers with twin or triple motors are ideal for the job, but an ordinary domestic hoover will do the job but slower.

10-10-20

https://www.boards.ie/discussion/comment/120085155#Comment_120085155

The telling of experience there. Sweet tips.

Girl Geraldine

I used 125mm duct as I already had a bunch of it lying in the yard with years as leftovers from another job so it cost me nothing.

I got cable in by using a fibreglass rod to pull it in. Only €30 for the day. No fluting around with aeroboard and string and hoovers.

kirk.

https://www.boards.ie/discussion/comment/120059165#Comment_120059165

I said 2.5 there for the swa .

Those units with pump and aerator were normally a separate 2.5

Adding a socket on the same cable complicates things really. A treatment unit is normally separate supply.

Girl Geraldine

There's no aerator here. Just a pump. 2.5mm swa twin cable put in with ip66 double switched socket all on 10A rcbo.

The only purpose of the socket is so that in the event of a pump failure, the pump can just be plugged out and replaced easily and quickly with a spare unit without any electrical work, save for attaching the 13A plug to the new pump flex (the flex must be passed through a 50mm duct between the pump chamber/shaft and micro pillar adjacent).

The whole idea of this arrangement is ease of maintenance, allowing a failed pump to be replaced with a spare in a matter of minutes.

I have bought a spare pump to keep for this very situation. It is inevitable that the pump will fail at some future time.

kirk.

I was talking about the second socket

Girl Geraldine

https://www.boards.ie/discussion/comment/120097883#Comment_120097883

I have one double 13A IP66 socket fitted into the micropillar. That is all.

Are you saying the double socket introduces some problem that wouldn't exist with a single socket?

The only reason i put in a double socket was because it is as easy to put in a double as put in a single. And it is handy to have just in case you ever had need to plug in something else if you were doing something out there. Like a tool, or even christmas lights or something.

Better looking at it than looking for it is my thinking on these things.

kirk.

It won't cause a problem but the treatment units are normally wired separate to anything

Some use a 5-core. An extra pair for a level alarm at the house