Connection in exterior concrete pad

Then you'll need a split box -- Code won't allow power and data cables to coexist in the same box.

Floor boxes are relatively common. You can find them that are fitted after-the-fact (i.e., bored) as well as cast in place. Some offer a "second chance" to tweek the set of the box after the concrete cures (often with a followup backfill operation).

Covers can be flush, pop-up, etc.

[no implied preference for this manufacture. rather, I just happened to be there looking for something else...]

Of course, any cabling (power and data) run into the boxe(s) will have to run through conduit *embedded* in the concrete (hint: look carefully at the route the conduit takes; straight pulls afford infinitely more joy than ones with lots of angles!)

I'm not sure I follow how you will *mate* to the box if it (and, presumably, any connectors therein) must be flush...

Running mains power in a "wet location" brings on a whole lotta pain (re: Code). Could you, possibly, consider running "low voltage" power to the box, instead?

Yes, some convention boxes are close but way too large.

The box is flush when unconnected and covered. When the connection is made there is a panel sitting over it which can conceal any plugged in connector and prevent tripping hazards.

That was the first thought. The panels use DC internally. Unfortunately it's only 24V. Would have been better at 48V but not enough time to get the internal components re-designed. We need around 1kW peak and running 70m or so of cable we are looking at a fair voltage drop.

Still might be worth revisiting to see if the components can withstand say 28V and deal with the voltage drop.

Thanks Don

Robert

re-reading that, it's very unclear. Think of the panel as a box 5" wide, by say a meter long and a meter high. Not accurate but close enough to get the concept across.

So the plug has plenty of room to extend above the pad when plugged in. Flush is only a concern when unplugged and covered by a simple plate.

Robert

Take a walk and see what is used in shopping malls and convention centre floors pehaps they use a suitable housing. Often used for kiosks etc which are moved around in malls.

Huh? You said 5" -- I assume "diameter" (or, "across a diagonal")?

should be almost exactly 5 inches diagonally...

Of course, that just gives you *one* connector (power) See below

OK. So, you're thinking of opening/removing a cover to expose the connector, mating to it and then hiding the "protrusion" under a panel.

From your followup to this post, it seems like you could afford a *second* box nearby that houses your data/signal connector? This would get around the prohibition against mains and signals in the same box -- and, the 5" limit on the (first) box...

Yikes! At 1kw, even 48V would require #10AWG wire. I'd have to look up the ohms/foot to figure what sort of a hit you'd take at 200+ ft...

At 24V it would probably be impractical (wire sizes).

So, plan on the data/signal cable coming up through another box (you can technically subdivide a box -- install a metal divider between the low and high voltage sections -- but finding boxes with this capability just makes your life more difficult)

I'm still at a loss as to how/what you can do to deal with the "damp/wet location" issue. E.g., kitchen counters must have outlets every 24". They can be above the counter (in the backsplash, etc.), below the counter, *on* the counter but not *in* the (top of the) counter -- for fear of liquids flowing into the receptacle.

You might be able to get around this by orienting the receptacle a different way and providing drainage? Likewise, you could arrange for the conduit to feed the box "from above" (even though below grade) on the premis that water doesn't flow uphill.

[You probably *really* want to talk to a Master Electrician and/or local inspector in your jurisdiction just to make sure you don't come up with a solution that is too clever for the Code Police :> ]

(without knowing your application, ) is there anything that you can

*rationalize* bringing power *with* to the site? E.g., a pair of lead acid batteries wired in series?

Or, any "easy" (i.e., "it's just money" :> ) way to cut power consumption in the devices used?

Please keep us appraised of how this sorts itself out!

Ever thought of box in building to "combine" power and data for the run to your unit, then run 48V AC to the unit, with suitable trips for leakage, thermal, shorts, water flooding. Then the conduit run can also be lower than the box inside the building to allow drainage at that end as well.

Still need hefty transformer etc. as well hefty cable.

Alternatively you could have an isolation transformer to supply

55-0-55, common on building sites and similar places for a mains supply that is 'safer'.

Also consider what is used for what is classed as street furniture for power signs, and other roadside units as the safety situations are similar. These often have forms of isolation trips so that when idiots drive into them the power is cut off quick.

Anyway food for thought.

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You'll never get a ~200 ft pipe to drain unless one end is on the top of a small *hill*! :>

In addition to safety concerns, you have to consider what happens to the conductors and insulation -- even with momentary exposure to liquids. Is it *just* water ("pure rainwater")? Are there any solvents that happened to get washed into the water? Any lime leeched from the surrounding concrete? And particulate matter that will lodge in the connectors?

This can interfere with signal/data contacts (plan on gold). It can also, over the years, cause a typical electrical outlet to mechanically and/or electrically fail.

The "Disconnect Box at source" is a good idea -- but you still have to be prepared for someone tho forget to shut it off. (I wonder if adding some "feedback" in the data/signal cables to energize a relay at the source gives you any leeway in terms of the Code?)

No longer considered "low voltage".

-------------^^^^^^^^^^

I don't think they are considered "wet/damp locations"

Yes I meant the point at which the outlet leaves the building is below the box in height to allow that end to drain as well. Draining from both ends means less slope required and actually small amounts are more likely to evaporate.

All good points.

Along with the temperature extremes, water (or other liquids) then freezing is another major issue.

Also make sure cabling is rodent and insect proof..

AFAIR especially in UK/EU for power wiring anything LESS than 1000V (1kV) is Low Voltage would need to check my regs, 55-0-55 is Reduced Low Voltage (RLV) anything below ABOUT 40V AC is Extra Low Voltage (ELV).

This sort of wiring is commune on building sites for portable power tools, nominally specified as 110V.

...

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That would be clased as normally inside a commercial premises or industrial premises.

Definitely not external wiring. Which is conisdered over here outside the Earth Zone as well as being wet/damp and many other things..

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200 ft of pipe. Not much air circulating through there.

And, no mention of where that 200 ft *runs* (e.g., if outdoors, you have to expect some amount of ground heave *or* parts of it will be significantly lower than the outlet to get below frost line)

Here (US -- as Robert used "inches" as a term of measurement, I assumed that a reasonably safe guess?), 50V is "low voltage". The next big change in regs comes at 600V (though I think there is another category at 250V)

There are also things like "power limited" circuits, etc.

Point being: make sure you talk to someone who knows what local ordinances will apply lest you come up with a solution that can't be installed (*sold* but not installed).

Most folks see the Code et al. as a "nuisance". I, OTOH, figure there is *some* reason, there -- even if it isn't spelled out explicitly (though the annotated code books try to put some explanation behind each requirement).

Also leads to some interesting implementations! E.g., we looked into using a pneumatically actuated switch for the garbage disposal to work around some of the "wet location" and "face up" requirements.

That's an interesting thought. Certainly a place to take a look.

Robert

Convention center box a-la

It's got the depth to accommodate a sealed connector but it is too large.

Yes and unsealed when connected. That seems to be the hard part.

Perhaps.

Yeah, why make it easy on ourselves?

Yes, first job is to make it as safe as practical, second is to meet code requirements. Finding an existing solution would make both easier.

Consultations will take place. I've started making contact.

Haven't figured out any so far. Unfortunately the power draw will last for hours.

I'll try to do that.

And thanks to everyone for the suggestions so far.

Robert

How deep do you *need* to go? Perhaps you can fit an extension onto the box. Or, stack one atop the other (bottom removed) to gain the additional depth -- since the sides will be continuous concrete...

Can you consider using an "unsealed" connector and counting on the box -- when closed -- to be "water/rain-tight"? I.e., when IN USE, does it still need to meet those requirements?

If it has to be sealed while in use, then the risk of liquids entering the box, etc. increases dramatically. I had assumed you only needed to be able to seal it up when *not* in use.

No doubt not as elegant as a "one box" solution. But, constraints may preclude that approach.

Perhaps a few square yards of PV's? :-/

Well, at least you don't have to *also* make it "inexpensive"!

They are, and they aren't, a nuisance.

Wiring codes - for the most part - are minimum guides for trade electricians. Particularly at low voltages they routinely permit installations that no safety conscious engineer (or sane person) ever would approve.

But then periodically the regs change for no apparent reason other than to stimulate business for electricians and suppliers. You compare the old and new regs and it's obvious that the new is not safer in any way - it's just different enough that existing installations have to be "fixed".

George

What the Code calls Low Voltage, AFAICT, *requires* close to nothing! I wanted to relocate the transformers for the landscape lighting to the back of the garage. This adds ~40 wire feet (each way) of conductor to the circuit. I figured I could just run a pair of 12's for each conductor (let's drive IR losses into the mud :> ) and satisfy *my* needs.

Of course, those 12's were going to come from some extra ROMEX I have lying around. "Hmmm... how will an electrician know that *this* ROMEX is carrying 12-24VAC while *that* ROMEX (a few inches away) is carrying mains voltage?"

And, what if there's a short or partial short. Granted, it's only a few hundred watts, but...

I don't know how "real" that scenario is. I.e., as a kid, I recall hearing (I hung around with lots of tradesmen) that any wiring that was NOT up to the latest code had to be upgraded *to* that code. It struck me, then, as silly: "Who the hell will ever hire an electrician to install an extra receptacle if that electrician is then going to turn around and say, 'I'm sorry, sir, but I have to remove all this K&T wiring and replace it with _______'?"

I suspect the practical effect is that these things just get conveniently ignored. OTOH, its hard to see writing a reg where you deliberately *allow* "bad practices" to remain in place...

Has anyone any experience with this from a *business location" point of view? I.e., perhaps there they are bigger "sticklers" for these details?

With the current connector candidate, 50mm.

That's essentially what the convention boxes appear to do. We have come up with a design we can build ourselves that uses the same principle but if we can find an existing solution it would make our life easier.

As I said, why make it easy on ourselves? It is, unfortunately to situation that needs to be worked to.

And the corresponding kWhs of batteries. :)

That was in the original design concept until the implications of the power requirements were pointed out. Then I think it failed on both aesthetic and cost grounds.

Thank heavens for small mercies.

Robert

"!

I suppose it's too late to consider power over ethernet or, gulp, some kinda domotics like X10?

There now are several states that require inspection for home sales and where either the seller or buyer *must* agree to fix any code violations or the home will lose its occupancy permit.

In most states, though, home sales still are caveat emptor.

Business and occupancy permits don't transfer with a commercial sale, so commercial properties can be sold with code violations because the new owner will need to get new permits anyway.

George