When a large sump pit (with pumps and floats installed inside) is placed some distance from the nearest wall, where is the receptacle put? If it is placed inside the pit at the highest point and the pump(s) fail, the receptacle will be potentially underwater. A person servicing the pump could be electrocuted.
Triple: Usually, all the pumps of this type I have seen are NOT plug-in; they are wired back to a controller. Most were two pumps, with an alternating relay, and 'both on' for a high water condition. There are usually two floats for the pump op; one for a 'normal on' level, one for a 'high level', and one for a high water alarm. I have never seen this wired to a receptacle.
If in fact this is a plug-in pump, it should be a single receptacle, GFI protected. I would hope it is up as high in the pit as possible, and accessable without having to enter the pit. A lock-out on the breaker may be a good idea also.
triple, Are you talking about poly-phase pumps? I had a situation over here that needed a solution similar to what you have there. What I did was made up some stainless steel bollards (for want of a better term) that had a base plate that was Dyna-Bolted to the floor (with stainless rawl-bolts) and from there, welded a plate on to the bollard to take the controls/pump isolator. Reason behind the stainless hardware is that if this area could be wet quite often, zinc-plated or even galvanised stuff is not going to last. In my niche of the trade (the dairy industry), things get wet all the time, use something like galvanised steel at your own peril. What's more, is that if you can plan it to have your conduit come up through where your bollard will be placed, you have instant mechanical protection for your wiring as it comes out of the ground.
Let's face it, these days if you're not young, you're old - Red Green
Sump / sewage pumps ... one of my favorite topics!
I'll tell you how, IMO, the job should be done. Period. Seldom seen, but still 'right.'
First off, don't put any sort of box or receptacle IN the pit. Even if they don't fill with muck or condensation, they will corrode at warp speed. Good luck undoing any screws. Ditto for the life expectancy of any wiring devices in the pit.
The only 'wiring accessory' in the pit should be a hook to hang up the coiled excess cords. (You'll want extra there when you need to replace something). You need this hook, or the wires will get tangled with the floats.
What you do is set a handhole right next to the pit. Connect the handhole to the pit with TWO large diameter sweeps, entering the bottom of the handhole.
Forget cable fill tables; the cable jackets WILL swell- a lot. Better to use 'huge' sweeps.'
I prefer sweeps to a straqight pipe run because they allow you to pull straight up, and foster drainage. Even so, there needs to be several inches of gravel under that handhole for drainage.
One sweep is for the float wires. The other is for the power wires.
Leave the wires LONG. Long enough to come out of the ground a couple feet. Unless, of course, you like working by laying on your belly and reaching into the muck to make your connections.
IDENTIFY the wires. Be able to tell, at a glance, which wires go to 'pump 1' or the 'middle float.'
Connections are made best by using wire nuts, then inserting the whole thing into a little epoxy pack. If the pump is for 'clean' water, you can get away with just dipping the nuts into Scotch-kote. When you fold - not coil- the wires into the handhole, set the nuts so they will tend to drain.
GFCI protection is generally not required, and maybe not even desireable. That's another discussion. What matters here is that the GFCI, if there is one, be located indoors, away from the pit, maybe even at the breaker.