Michael Rapp
Carpal Tunnel
Reged: 04/27/04
Posts: 2576
Loc: Dickinson, TX
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Like many things with my observatory project, my initial common sense notions have turned out to me horribly awry.
Here is how I was intending to get electricity to my observatory, which is roughly 25 feet away from the house. Near the house's backdoor is a GFCI outdoor outlet. I was planning on running the best outdoor extension cord (one of the ones rated for large appliances) from that outlet into the observatory. I would bury the cord in PVC pipe 18" into the ground. I would construct "shields" over the GFCI outlet to ensure that it was protected from the elements (and well-meaning lawn equipment).
A modest UPS would be plugged into this cord and into that would be a Meade LXD-75 mount, a Pentium III with monitor and speakers, a 40 pint dehumidifer, and one or two other scope accessories.
Is this a safe and practical way of getting electricity into my observatory?
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--Michael
Meade 8" f/6 Dob, Lunt 35mm | TeleVue 32, 13, 7.4 Plossls
Observatory: 10/27/2006 (First Light) - 9/13/2008 (Hurricane Ike)
My Sketches | Michael_in_TX on NSN
I am looking for a 1980s Edmund Scientific 3" f/10 red-tube reflector, PM me if you have or know of one!
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BluewaterObserva
Postmaster
Reged: 05/18/04
Posts: 5748
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It's OK. You really want it in the ground? I think I would solicit the help of an electrician on it and go ahead and run it to your breaker panel.
Even the best of extension cord is not at all what I call a permanent solution is all.
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Spoonsize
DURHAM 157494
Reged: 08/27/04
Posts: 4141
Loc: Stuck in a Time Warp.
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The short answer is probably. But, if only 25 feet from the house, why bury it at all? Roll it up when not in use and hang it on the side of the observatory.
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IF YOU COULD SEE FROM WHENCE YOU CAME YOU WOULD KNOW WHERE YOU'RE GOING TOO.
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BluewaterObserva
Postmaster
Reged: 05/18/04
Posts: 5748
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Well, rolling it up and out when in use would not be good for any sort of traffic area in the yard or property.
But maybe a pole could get you there over head?
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NeoDinian
Experienced Postmaster
Reged: 10/05/05
Posts: 14043
Loc: Rockford Illinois
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The extension cord is fine for "Temporary" use. If you plan a permenent solution, you "SHOULD" get the proper wire for the job. A 50 foot roll of 12 guage "Bury" cable is only like 45-60 dollars.
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Neo... (Jeff)
-=-=-=-=-=-=-
10" LX200-GPS/SMT UHTC "Draco"
 Rockford, Il.
NeoDinian's Eye on the Sky!
Coming soon:
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RogerRZ
Whatta you lookin' at?
Reged: 01/09/06
Posts: 3082
Loc: West Collette, NB, Canada
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I wish I was as close... My observatory is 300 yards from the nearest power source. An underground cable would cost as much, if not more than the building itself.
Portable power it is...
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-Roger Pitre-
1 X 7 binocular
MN65, Nexstar 8SE, SV70ED, Lunt 60 PT
EQ6 Pro, Canon 50D, Modified XSi, SBIG ST-2000XM, 70-200 f/4L, BackyardEOS
"He's got shoulders on him like a smelt..."--Anonymous
http://www.facebook.com/album.php?aid=10723&id=509325956&l=79d06a1d10
http://ajpobservatory.is-great.org/
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Moggi1964
Vendor - Astro Laugh
Reged: 11/07/05
Posts: 3636
Loc: Madison. NJ. USA
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Quote:
I wish I was as close... My observatory is 300 yards from the nearest power source. An underground cable would cost as much, if not more than the building itself.
Portable power it is...
If I put an observatory 300ft from my power source it would be at least four neighbours gardens away 
Oh to have a problem like yours 
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Morris
www.astrolaugh.com
Astrosystems Telekit 10" with F/6 JC Wilkinson mirror
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Michael Rapp
Carpal Tunnel
Reged: 04/27/04
Posts: 2576
Loc: Dickinson, TX
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If I do decide to go with an electrician, which it is looking like I will, what kind of information will I need to provide?
Do I just total up the amps of all of my equipment and supply them that number and let them do the rest? What types of questions might I get asked (other than why does your roof come off)?
Can I expect an electrical contractor to do the entire job, that is...installing the breaker, running the line, digging the trench, installing the outlet, etc?
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--Michael
Meade 8" f/6 Dob, Lunt 35mm | TeleVue 32, 13, 7.4 Plossls
Observatory: 10/27/2006 (First Light) - 9/13/2008 (Hurricane Ike)
My Sketches | Michael_in_TX on NSN
I am looking for a 1980s Edmund Scientific 3" f/10 red-tube reflector, PM me if you have or know of one!
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LateViewer
Pooh-Bah
Reged: 11/17/05
Posts: 1009
Loc: Manhattan
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You're not about to make a horrible mistake but you are about to make some code violations.
First of all, the extension cord is not to be buried in the PVC conduit you are installing unless it is specifically rated for it. Also, use UL listed schedule 40 or 80 PVC electrical conduit for electrical work.
If you do run the conduit underground, 18" is the minimum depth except where it comes up through the ground to enter your building.
You can pull 3, one white, one black and one green, no. 12 THHN/THWN building wire directly through the conduit. Run the coduit all the way to your first box in the observatory. If the wiring is exposed I would use conduit throughout.
Before your wire enters into a receptacle box in the observatory, it needs to pass through a box with a disconnect in it. In garages and outbuildings on a residential property this disconnect can be an ordinary light switch. This disconnects the feed coming in from the branch circuit wiring, outlets, in the observatory. If you were to run 2 hots, so that you had a 220 Volt circuit the switch would need to be a double pole single throw switch. As opposed to the regular light switch which is single pole single throw.
So that's how to do it.
Good luck.
Al
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Chance favors the prepared astronomer.
Yeah I have some stuff.
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Mike Clemens
Frozen to Eyepiece
Reged: 11/26/05
Posts: 6707
Loc: Alaska, USA
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I've got a disconnect panel ("farm panel") on the back of my house, so my own plan is to use that, drop out of that with some conduit for protection, with some 8-3 UF cable to a small panel on the observatory. Having a subpanel out there with its own ground rods makes me feel better considering recent lightning strikes in the neighborhood.
I also want to run a length of 12-3 UF for a 3 way switch loop, so I can turn some outdoor observatory mounted lights on or off from both the observatory and the house. Hmm I wonder if that should come out of the observatory panel or the house panel!
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http://www.pbase.com/mclemens1969/tec_200_observations
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NeoDinian
Experienced Postmaster
Reged: 10/05/05
Posts: 14043
Loc: Rockford Illinois
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Some places will allow you to do your own electric work for internal (running outlets, etc), and even outdoor (Bury cable), but the final connections to the breaker-box is usually done by a qualified electrican, and an inspection is usually required as well.
Doing electrical work is easy actually.
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Neo... (Jeff)
-=-=-=-=-=-=-
10" LX200-GPS/SMT UHTC "Draco"
Rockford, Il.
NeoDinian's Eye on the Sky!
Coming soon:
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RogerRZ
Whatta you lookin' at?
Reged: 01/09/06
Posts: 3082
Loc: West Collette, NB, Canada
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Quote:
Quote:
I wish I was as close... My observatory is 300 yards from the nearest power source. An underground cable would cost as much, if not more than the building itself.
Portable power it is...
If I put an observatory 300ft from my power source it would be at least four neighbours gardens away
Oh to have a problem like yours
I could have put over a mile away from my power source, across a thirty foot wide brook and a bog, and even go from yellow to green on the light pollution map, and still have it on my property. I'm sitting on almost 100 acres... 
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-Roger Pitre-
1 X 7 binocular
MN65, Nexstar 8SE, SV70ED, Lunt 60 PT
EQ6 Pro, Canon 50D, Modified XSi, SBIG ST-2000XM, 70-200 f/4L, BackyardEOS
"He's got shoulders on him like a smelt..."--Anonymous
http://www.facebook.com/album.php?aid=10723&id=509325956&l=79d06a1d10
http://ajpobservatory.is-great.org/
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rmcpb
Carpal Tunnel
Reged: 11/16/04
Posts: 1606
Loc: Blue Mountains, NSW, Australia
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For that job you have two choices as I see it:
- Get an electrician in to do the job, possibly with you digging the trench to keep the costs down or,
- Go for portable or solar power based on deep cycle batteries.
With the distance you are looking at I think I would opt for the first choice.
Good luck
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Rob Browne
8" & 13" Dobs
Equatorial Platform
Couple of Panoptics and a handful of BO/TMBs
9x60 binocs
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JAT Observatory
NOT a Wimp
Reged: 02/20/05
Posts: 8893
Loc: In the Primordial Soup
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My observatory is about the same distance from the house as your. It was originally designed to be solar powered. About 1-1/2 years ago I ran AC so I could power the dehumidifier. To get the power to the observatory I removed a flood light that was attached to the rear wall of the garage and installed a weather proof switch box. From the box I run the conduit and wire to the observatory. The conduit is not buried quite 18 deep but it has a layer or gravel over top so if someone digs there theyll hit the gravel right before the conduit. On back side of the observatory there are 2 outdoor outlets, and power enters the observatory from there. The outlets are handy for when I am doing stuff outside in the yard as I no longer need to run an extension cord from the house. No electrician was involved. 
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-Marcus
Hey what did you expect? After all, I am just a pig with a nice smile!
www.jatobservatory.org
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LateViewer
Pooh-Bah
Reged: 11/17/05
Posts: 1009
Loc: Manhattan
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I am shopping land west of the Catskills in NYS, the darkest skies in the NY Metro area, and solar panels make lots of sense for many of the sites I am considering.
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Chance favors the prepared astronomer.
Yeah I have some stuff.
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JAT Observatory
NOT a Wimp
Reged: 02/20/05
Posts: 8893
Loc: In the Primordial Soup
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Solar power is great, but it requires some very careful planning to size the panels and the batteries correctly. You also have to look at battery types, capacity and usage patterns. While I don't regret installing solar there are some things I would do differently if I had to do it over again. Also the reason I went solar was the observatory was going to be in a different location on the property than where it finally ended up. We also used to have frequent power failures. By the time I realized I could put the observatory where I originally wanted the solar panel had already be delivered, so I used it. I have to admit though there have been a few power failures after the AC line was run and I was glad I had a solar/battery system. While currently only about 50% of the system uses the battery/solar power, it can be converted back to full battery and solar power in about 5 minutes, minus the dehumidifier and desktop computer (a laptop is used instead).
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-Marcus
Hey what did you expect? After all, I am just a pig with a nice smile!
www.jatobservatory.org
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LateViewer
Pooh-Bah
Reged: 11/17/05
Posts: 1009
Loc: Manhattan
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"I also want to run a length of 12-3 UF for a 3 way switch loop, so I can turn some outdoor observatory mounted lights on or off from both the observatory and the house. Hmm I wonder if that should come out of the observatory panel or the house panel! "
In that an outbuilding, such as an observatory, needs a method of disconnecting all current carrying conductors, (hot legs), from their source feed, then a light in the observatory that is controlled by a 3 way switch in the house and the observatory, would need to have as its source the panel in the observatory because if one were to kill the observatory panel the light would be dead. If you were to feed the light from the house, you could kill the observatory panel and still have a hot circuit to the light.
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Chance favors the prepared astronomer.
Yeah I have some stuff.
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Mike Clemens
Frozen to Eyepiece
Reged: 11/26/05
Posts: 6707
Loc: Alaska, USA
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thanks for the tip!
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http://www.pbase.com/mclemens1969/tec_200_observations
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Anonymous
Unregistered
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On the three way switch in the house and observatory, are you concerned with your wife flipping on the lights when it's time for the dog to go outside?
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PJ Anway
Carpal Tunnel
Reged: 06/04/03
Posts: 2165
Loc: North Coast
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Here are the rules for underground services to an out building:
1) Direct burial cable/conductors 24 below grade
2) Wires in nonmetallic conduit 18 below grade
3) A single residential branch circuit protected by GFI 12 below grade
4) Any of these can be reduced to 6 below grade if covered with 2 of concrete
5) 1), & 2) require a warning ribbon to be buried 12 above conductors/conduit
Receptacles in the observatory must be on a GFI circuit.
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Clear Skies,
PJ
http://doublestarobserver.com
Refl.- 203/1420, Refr.- 100/1000, 75/500, 63/840, Bino.- 15X60, 10X50
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