Thoughts please on an inspection pit

[Mickindashed]

I'm replacing a run of old sheds with a newer building and I'm thinking of putting in an inspection pit so I can drive a car over it and work on it from below. Now to my mind it's all very simple. I just dig a trench down the middle of the hole I'll be digging anyway for the base, line it with a membrane, brick up the sides, pour in some concrete for the floor and it's done. I'd run some leccy in there for lights and a couple of sockets while I'm at it. If I hadn't googled the thing i'd have been happy, but I've been reading up on the idea and the thing I keep seeing is that inspection puts are fire hazards and basically not permitted any more. I'm only looking at this from a hobby perspective so I'm taking the health and safety stuff with a pinch of salt, but I'm not an idiot either so if this is a bad idea I'll drop it. Has anyone got knowledge on the subject?

[julianf]

My ex-neighbour had one.

I cant recall the exact details, but IIRC, he had a fan in there, on a timer, to vent out the air.  He had not used it in years, but i think the fan was still set.

His was a welded steel box, dropped into the hole.  He was an ex engineer, rather than really an auto mechanic, so, possibly, he got the metal on the cheap or somthing

[Soft top]

I have built my own pit. First I dug a big hole then poured concrete in to form the floor and the footings for the walls. I then built the walls up. I staggered the thickness of the walls, starting at about 30" thick at the bottom. They have to be thick because they are retaining walls.
At one end I staggered the wall thickness the opposite way round which made steps to walk down. I then tanked it all inside with paint on tanking slurry. Built it 15 years ago and its still good and dry.
As for the safety bit. I have never touched anything to do with petrol above the pit and, because it is in a garage, if I want to run an engine I open the garage doors and I move the car back so the exhaust is outside.

[greasemonkey]

I've used quite a few, from top notch professional ones, all the way to flooded diy ones, that had to be emptied with a bucket before using.

Depending on what type of soil you have, one or two rows of nine inch hollows, filled, should be enough. You'll need to know how much water is coming through the ground, you may or may not need to drain and water proof it. Personally, I'd at least aim to get a drain in there somewhere, and back fill with draining stone.
If there is any chance of water, leave a sump so you can get a pump in.

It's easier to stand on something, than spend all day bent over. Go deep enough.
Make it long enough so that a car doesnt block you exit if it moves. Ideally, you should be able to get out both ends, in case you down there by yourself, and something blocks the one end. ( like an asteroid falling against the car or something.........)

I've never been gassed or blown up in a pit. I suppose it could happen. It isn't something I'd have much concern about. It might be different if I was working on LPG cars or something,

Keep an eye out for a Four poster ramp. It might be cheaper than digging a pit in, and a lot handier. Old ones don't make that much money.

[Mickindashed]

Thanks guys.

[Dickjotec]

Alternativly look out for a portable vehicle lift. A friend and me picked up a hydraulic one at a sale for £200. Goes flat to the floor, has wheels for moving   and lifts a land rover to working height. Excellent for welding as you can tilt it so you are not welding overhead.

[greasemonkey]

That lift sounds real interesting. Tilting to weld would be marvellous.

[BANDIT2]

Nah.. you've never lived until you've had a ball of molten weld melting its way through a thin layer of ear wax before cauterising your ear drum haha!

[Jamesrl]

Nah.. you've never lived until you've had a ball of molten weld melting its way through a thin layer of ear wax before cauterising your ear drum haha!

If that's the case I've lived several lives, it got the point where I expected it every time I welded a car.

[BANDIT2]

Yes, and the 'dance of the burning arse hair' is another.
I got it down to 3.122 secs from smelling the hair burn to complete boilersuit/underpants removal.

[greasemonkey]

It'll be fine, its only a spark.........maybe a blob of weld, it'll stop burning in a second............it can't be that bad............it is bad........it's in my boot..............by the time I've taken the mask off put the torch down, it's gonna be deep.............. HELP!

[Soft top]

Yes, and the 'dance of the burning arse hair' is another.
I got it down to 3.122 secs from smelling the hair burn to complete boilersuit/underpants removal.

I have a self extinguishing system.................
Was once laying on my back welding under a car.  Lump of hot molten weld fell and went through top of trousers...........
then continued through side of my urostomy bag..........
contents of which, suddenly released put the fire out!!!!!!!   Did smell a bit though 

[BANDIT2]

This is a true story- many yrs ago I got myself a new s/h motor, Cortina mk2 1300 estate. Being of an age when cars didn't all have fag lighters or radios and I liked a fag and the Stranglers on tape were beckining.
Fitted a radio/cassete-no problems there,then popped down to the local motor factors for a fag lighter,the type that had a surround that lit up at night,no cheap non-illuminateing tat was going in my pussy wagon, no sir, only the best- '£1.29 mate' sez the purveyer of quality motor parts and I eagerly handed over the cash and rushed home as fast as a pre cross flow 1300 ford could,to fit it.
Wired it up and... oh, hang on , I digress a bit..
Remember those doc martin boots that went half way up your calf and took 10 mins to lace up? you do? good, I'll carry on then..
Right, where was I? .....Oh yes, ok.. all wired up, lights on and success! the green ring lit up and went off when the lights went off.
I then rolled a fat one and pressed the lighter in and waited.........
and waited.......
and waited...... until...
smoke!! and lots of it!!! and still it hadn't popped!!!
So I pulls it and its stuck so I pulls it harder and out she comes , I look at the electric cooker ring thing and note that it is white hot just before it drops off and goes down the inside of the aforementioned doc martin boot. The pain was instant and very intense causeing me to leap up out of the drivers seat smashing the radio/cassete and In my panic to undo the 15 foot long laces on the docs , I 'pulled' the bow and was left with a knot so small and tight that sissors were the only option
It melted that far into the flesh of my ankle the doc had to cut it out.. along with a piece of my nylon sock.

[greasemonkey]

Ha ha ha! Bet that tickled a bit.

[Tony]

Just read this after Bandit2's post about returning and wondering when he was last on, don't know how I missed this hilarious story, just chuckling away to myself at work.   Bet that hurt pretty badly...