Connection in exterior concrete pad

A company I'm working with is developing an application the needs to
connect power and data (standard 110V/60Hz and RS485 type data)
on a flat exterior concrete pad.

We have connectors that we think will do the job (IP68 with power
and data) but we are looking for a connection box that can be cast
in place in the concrete for the pad side of the connection.  It has
to be flush with the concrete so there is no trip hazard when
unplugged and have a cover (ditto).  The cover can certainly be one
that is removed and replaced as needed.  Obviously it needs to
prevent water entering the cable conduit, the receptacle we are
looking at has a bulkhead seal option so  some sort of divided
box might suit. The climate includes freezing weather, the worst
appears to be -31.  I suspect the ground is more temperate than
the air.

Oh and it should be less than 5" in size (it will be covered by the
devices using it when in use).

We haven't found a good off the shelf item to do this and I'm
wondering if anyone has found or built one for other projects.

We have found a possibly suitable connector but are open
to suggestions on that as well.

Robert

Hi Robert,

On 9/9/2011 12:51 PM, Robert Adsett wrote:
> A company I'm working with is developing an application the needs to
> connect power and data (standard 110V/60Hz and RS485 type data)
> on a flat exterior concrete pad.

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

> We have connectors that we think will do the job (IP68 with power
> and data) but we are looking for a connection box that can be cast
> in place in the concrete for the pad side of the connection.  It has
> to be flush with the concrete so there is no trip hazard when
> unplugged and have a cover (ditto).  The cover can certainly be one
> that is removed and replaced as needed.

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.

http://www.lewelectric.com/32-series/
http://www.lewelectric.com/1101-series/
http://www.lewelectric.com/pufp-series/

[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!)

>  Obviously it needs to
> prevent water entering the cable conduit, the receptacle we are
> looking at has a bulkhead seal option so  some sort of divided
> box might suit. The climate includes freezing weather, the worst
> appears to be -31.  I suspect the ground is more temperate than
> the air.

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?

> Oh and it should be less than 5" in size (it will be covered by the
> devices using it when in use).
>
> We haven't found a good off the shelf item to do this and I'm
> wondering if anyone has found or built one for other projects.
>
> We have found a possibly suitable connector but are open
> to suggestions on that as well.

On Sep 9, 4:08=A0pm, Don Y <nowh...@here.com> wrote:
> Floor boxes are relatively common. =A0You 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).

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

> > =A0Obviously it needs to
> > prevent water entering the cable conduit, the receptacle we are
> > looking at has a bulkhead seal option so =A0some sort of divided
> > box might suit. The climate includes freezing weather, the worst
> > appears to be -31. =A0I suspect the ground is more temperate than
> > the air.
>
> I'm not sure I follow how you will *mate* to the box if it (and,
> presumably, any connectors therein) must be flush...

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.

> Running mains power in a "wet location" brings on a whole lotta pain
> (re: Code). =A0Could you, possibly, consider running "low voltage" power
> to the box, instead?

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

On Sep 9, 11:58=A0pm, Robert Adsett <s...@aeolusdevelopment.com> wrote:
> On Sep 9, 4:08=A0pm, Don Y <nowh...@here.com> wrote:
>
> > Floor boxes are relatively common. =A0You 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).
>
> Yes, some convention boxes are close but way too large.
>
> > > =A0Obviously it needs to
> > > prevent water entering the cable conduit, the receptacle we are
> > > looking at has a bulkhead seal option so =A0some sort of divided
> > > box might suit. The climate includes freezing weather, the worst
> > > appears to be -31. =A0I suspect the ground is more temperate than
> > > the air.
>
> > I'm not sure I follow how you will *mate* to the box if it (and,
> > presumably, any connectors therein) must be flush...
>
> The box is flush when unconnected and covered. =A0When the connection
> is made there is a panel sitting over it which can conceal any
> plugged
> in connector and prevent tripping hazards.

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

"Robert Adsett" <sub2@aeolusdevelopment.com> wrote in message 
news:120490fb-ba6c-43b3-87b4-cfb63eeac3e1@c29g2000yqd.googlegroups.com...
>A company I'm working with is developing an application the needs to
> connect power and data (standard 110V/60Hz and RS485 type data)
> on a flat exterior concrete pad.
>
> We have connectors that we think will do the job (IP68 with power
> and data) but we are looking for a connection box that can be cast
> in place in the concrete for the pad side of the connection.  It has
> to be flush with the concrete so there is no trip hazard when
> unplugged and have a cover (ditto).  The cover can certainly be one
> that is removed and replaced as needed.  Obviously it needs to
> prevent water entering the cable conduit, the receptacle we are
> looking at has a bulkhead seal option so  some sort of divided
> box might suit. The climate includes freezing weather, the worst
> appears to be -31.  I suspect the ground is more temperate than
> the air.
>
> Oh and it should be less than 5" in size (it will be covered by the
> devices using it when in use).
>
> We haven't found a good off the shelf item to do this and I'm
> wondering if anyone has found or built one for other projects.
>
> We have found a possibly suitable connector but are open
> to suggestions on that as well.
>
> 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.

Hi Robert,

On 9/9/2011 8:58 PM, Robert Adsett wrote:
> On Sep 9, 4:08 pm, Don Y<nowh...@here.com>  wrote:
>> 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).
>
> Yes, some convention boxes are close but way too large.

Huh?  You said 5" -- I assume "diameter" (or, "across a diagonal")?
<http://www.lewelectric.com/wp-content/gallery/1101-series/6304-be.jpg>
should be almost exactly 5 inches diagonally...

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

>>>   Obviously it needs to
>>> prevent water entering the cable conduit, the receptacle we are
>>> looking at has a bulkhead seal option so  some sort of divided
>>> box might suit. The climate includes freezing weather, the worst
>>> appears to be -31.  I suspect the ground is more temperate than
>>> the air.
>>
>> I'm not sure I follow how you will *mate* to the box if it (and,
>> presumably, any connectors therein) must be flush...
>
> 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.

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...

>> 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?
>
> 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.

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  :>  ]

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

(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!

In article <8ccc1281-d247-4dae-8789-
d6625ef2a1ab@j19g2000yqc.googlegroups.com>, sub2@aeolusdevelopment.com 
says...
> 
> On Sep 9, 4:08&#4294967295;pm, Don Y <nowh...@here.com> wrote:
> > Floor boxes are relatively common. &#4294967295;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).
> 
> Yes, some convention boxes are close but way too large.
> 
> > > &#4294967295;Obviously it needs to
> > > prevent water entering the cable conduit, the receptacle we are
> > > looking at has a bulkhead seal option so &#4294967295;some sort of divided
> > > box might suit. The climate includes freezing weather, the worst
> > > appears to be -31. &#4294967295;I suspect the ground is more temperate than
> > > the air.
> >
> > I'm not sure I follow how you will *mate* to the box if it (and,
> > presumably, any connectors therein) must be flush...
> 
> 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.
> 
> > Running mains power in a "wet location" brings on a whole lotta pain
> > (re: Code). &#4294967295;Could you, possibly, consider running "low voltage" power
> > to the box, instead?
> 
> 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.

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.


-- 
Paul Carpenter          | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/>    PC Services
<http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font
<http://www.gnuh8.org.uk/>  GNU H8 - compiler & Renesas H8/H8S/H8 Tiny
<http://www.badweb.org.uk/> For those web sites you hate

Hi Paul,

On 9/10/2011 1:29 AM, Paul wrote:

>>> 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?
>>
>> 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.
>
> 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.

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?)

> 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'.

No longer considered "low voltage".

> 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.

Hi Dennis,

On 9/9/2011 10:26 PM, Dennis wrote:
> "Robert Adsett"<sub2@aeolusdevelopment.com>  wrote in message
> news:120490fb-ba6c-43b3-87b4-cfb63eeac3e1@c29g2000yqd.googlegroups.com...
>> A company I'm working with is developing an application the needs to
>> connect power and data (standard 110V/60Hz and RS485 type data)
>> on a flat exterior concrete pad.

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

>> We have connectors that we think will do the job (IP68 with power
>> and data) but we are looking for a connection box that can be cast
>> in place in the concrete for the pad side of the connection.  It has
>> to be flush with the concrete so there is no trip hazard when
>> unplugged and have a cover (ditto).  The cover can certainly be one
>> that is removed and replaced as needed.  Obviously it needs to
>> prevent water entering the cable conduit, the receptacle we are
>> looking at has a bulkhead seal option so  some sort of divided
>> box might suit. The climate includes freezing weather, the worst
>> appears to be -31.  I suspect the ground is more temperate than
>> the air.

> 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.

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

In article <j4g8tt$v2$1@speranza.aioe.org>, nowhere@here.com says...
> 
> Hi Paul,
> 
> On 9/10/2011 1:29 AM, Paul wrote:
> 
> >>> 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?
> >>
> >> 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.
> >
> > 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.
> 
> You'll never get a ~200 ft pipe to drain unless one end is
> on the top of a small *hill*!  :>

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.

> 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?

All good points.
 
> 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.

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

Also make sure cabling is rodent and insect proof..
 
> 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?)
> 
> > 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'.
> 
> No longer considered "low voltage".

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.

...

-- 
Paul Carpenter          | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/>    PC Services
<http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font
<http://www.gnuh8.org.uk/>  GNU H8 - compiler & Renesas H8/H8S/H8 Tiny
<http://www.badweb.org.uk/> For those web sites you hate