Underground services

[Huge]

A single 35m length? I think not.

[Adrian Caspersz]

Light string tied to a tissue and a vacuum cleaner.

[Adrian Caspersz]

Oops, er, finger trouble.

[Adrian Caspersz]

How do ye then get the hamster/rat out of Henry?

[Huge]

W-e-e-e-e-llll. I have high hopes. We had one trip on the 9th and two on the 10th April after some weeks without one. One of those was a genuine fault; I plugged in the charger for my inspection lamp and got a big blue flash. It tripped both the MCB for that ring and the RCD, and the charger is now dead, so I count that as a genuine fault.

The other two were caused by plugging in a different wall-wart (the charger for my MacBook) and an old favourite - switching on the garage lights.

So, I finally swapped out the RCD for a new one I've had for some time, on the 11th. I've spent the intervening days switching the garage and workshop lights off and on at regular intervals, without a single trip. Doing this, especially the workshop (where the fluorescent lights are actually fed from a power circuit) usually

I'm keeping my fingers crossed.

[Huge]

[13 lines snipped]

[Oops. Interrupted by the tiler.]

... tripped it pretty "reliably".

[The Natural Philosopher]

Easy. open up the top, take out the bag, extract hamster and then use (reassembled) Henry to get the fluff off hamster, retaining hamster bu the rear facing appendage.

[Mike Tomlinson]

En el artículo , Huge escribió:

Ta. Hopefully it's done the trick

[Huge]

Bloody hope so.

:o)

[Tim Watts]

Mains = LV

[Capitol]

When I did this, I ran the SWA in air as a separate feed from a dedicated garage consumer unit, spurred from the incoming feed to the house CU. A Wylex switch isolator was used to split the incoming supply. I ran all the signal wiring(phone, 3 x cat 5, UHF up UHF down, Video up, audio up/down in galvanised piping, which supported the SWA, I didn't feed water as there was no easy way to provide drainage. I would have run the water as a separate poly pipe. This was some considerable time back. It has been trouble free. If I were doing it again, I would put in drainage, with water alongside in the same trench. This would give me a local toilet facility. I would also run optical fibre up the piping to try to future proof the data side of things. It reads as though your mains supply is crap if the volts drop that badly. Overhead supply?

When I redid the garage, it ended up with a dedicated 32A 240V ring main on the workshop CU and 32 socket outlets, together with the same for 110V as I have a lot of US tools. The lighting is run from a separate 10A supply on a different CU, for safety(quite difficult to end up in the dark after doing something which knocks out the garage ring main) and uses 12 x 5ft fluorescent tubes. The switch on surge is a bit high as they are not PFC. Now, I'd consider LED equivalents. The garage ring main needed a type C MCB to cope with switch on surges from 110V transformers.

[www.GymRatZ.co.uk]

BT conduit that runs to our house is jointed whereas the black 1/2" waterpipe the original BT telephone line was run in was joint free all the way into the garage. Unfortunately, having found the "actual" black water pipe the builders simply ripped out the BT waterpipe conduit with their mini-digger....

Hence the new stuff being fitted.

[Tricky Dicky]

In our first house built in the 70's there was a piece of standard clay dra inage pipe that disappeared through that sub-floor and curved out through t he wall below ground level. Both the electric supply and water supply enter ed the house through this pipe. Beyond the house as far as I know both serv ices were simply buried in a trench through the garden joining the mains un der the pavement. I do not know what separation existed between services in the trench but suspect it depended on what dug the trench.

Richard

[harry]

A vacuum cleaner works perfectly well, sucks a bit of paper tied to string through the pipe

[ARW]

At 35m and no pull cord there is only one option.

A Cobra duct rod.

[nospam]

On 19/04/2017 14:44, Adrian Caspersz wrote: ... snipped

This seems like an appropriate moment to remind people about Raggot

although it involves a Gerbil rather than a Hamster

[Mike Tomlinson]

En el artículo , ARW escribió:

I could lend out one of my kittens and some catnip.

[ARW]

The cable would need to be waterproof (eg Hituff would be allowed but not T&E). The conduit will be full of water.

Not really. You can of course run the water pipe in the same trench as the conduit - subject to some minimum distance between the two that I do not know off hand.

I would not bother. If done properly then local protection is better.

LED florescent replacement lamps should sort that (ducks)

Up to you. It's your house.

Some people would and not be able to sleep without it (I'll never be able to sell my house or the Prat P police will be knocking at my door type nightmares)

Others could not give a f*ck as long as the job is done properly and safely.

You are going to need a biggish[1] cable (probably 10mm^2). Not due to the actual current load and current carrying capacity of the cable (you have said that it is 32A) but due to voltage drop when using the full

32A at 35m.

My suggestion would be to have SWA and the water pipe laid directly in the trench next to a conduit for the telephone/intercom services.

[1] This probably means you will have to use SWA.

[John Rumm]

Yes

Its usually suggested that they are segregated - even if its only by a conduit with separate compartments. You could achieve the same result buy burying at different depths in the same trench.

Consider what the requirements are with respect to lighting. Will you be working out there at night (or other time when lights are required)? would a loss of light prove potentially dangerous? If the answer to those is yes, then you need to ensure the lights stay on when you get a power circuit trip. That may be by ensuring discrimination of the circuits, or possibly by including battery maintained emergency lighting.

In my workshop I decided that loss of lighting was not acceptable. So I have a submain feed to a garage CU with a 32A fuse at the head end, and a Type S 100mA RCD (TT earthing here). That feeds a split load CU with lights on the non RCD side, and a separate 30mA trip RCD on the power circuits (B32 MCB - which will *probably* discriminate with the upstream HRC fuse in the event of a fault).

Still a good choice. Ones with LED tubes, and / or rectangular LED panels are also a good option.

Do you care? ;-)

Garden work is no longer covered by part P. New circuits however still are as is replacement of a CU.

Check your voltage drop limits - remember that the threshold is different for power and lighting circuits these days (5%, and 3%)

[John Rumm]