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Power runs to observatory, type of wire, placement, boxes?

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#51 spacemunkee

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Posted 20 July 2019 - 08:57 PM

The orange "Romex" is #10, by the recent color codes I have seen.  #14 is white, #12 is yellow, #10 is orange, black is #8 or #6, gray is for UF.

 

Edit:  If you want to run in conduit you could run three #10, or three #12 THWN or XLPE insulated copper wires in 1/2 inch galvanized RIGID conduit, and you would only need to bury 6 inches deep.  That's a shovel job.  As far as I know, there's no depth requirement for data cables, but correct me if I'm wrong.

 

If you run the conductors to the observatory directly to a receptacle or receptacles, from a GFCI breaker in the garage box, I believe you would not need a ground rod at the observatory.  That way, it's a branch circuit, not a feeder to a sub-panel.

There are some codes for low voltage/data, but would have to pull out the book to check, as they are generally uncared about. 

 

I believe the OP's "electrician"  is saying drive a ground rod(which should be driven vertical 8', not dropped flat 2 feet deep in a trench cause you're to lazy to drive it) in place of grounding back to main service. No no, as Rick and I pointed toward.

 

Its an area where the code is up to interpretation(as a lot of the book seems to be, have had two inspectors tell me two different things)tongue2.gif

 

Arguments either way saying an earthen ground at a detached structure gives "potential" of this and that, vs. stopping something such as a lighting strike from making it back to the main house. No matter what should have that ground back to service entrance.

 

County I live in, detached garage, that feeder ground covers it. County I border where 90% of my work is, have to have a rebar(ufer) bond along with the ground in the feeder. If only one branch circuit feeding it, then no need. Two or more, rebar bond, even if its 2 separate circuits and not a sub. Ground rod wont cut it..

 

They also require a load calculation(as per code requirements), unlike the county I live in. Don't care if you wired a screened in porch on a 1500sq. ft. house with a 200 amp service. Gotta make sure your not overloading that service. Though I have had them let me slide a couple times.

 

But with that they get $25.25 to check my math and send me an email saying "your calculations have been approved based on the information you submitted", field inspector never sees it.tongue2.gif  And another $30.30 trip charge to swing through to look at clamp on rebar before concrete is poured. Why everything in even $ and cents? I asked one day. Cause they have to give the state their 1%..

 

Anyway, I'm ranting. smile.gif

 

GFCI is fine at panel or at first receptacle at obs.

 

 

 

Someone cut corners to save a few dollars or save a short trip on that installation.  They are using a bare wire for a neutral, and have taped a white to function as black (conductor), it appears.  They should have run a 4 wire #10 cable, with black, red, white (neutral) and bare (gnd).  It really should be redone, if possible, IMO.

Agree should be corrected, but how many houses/garages are out there with that installation for many years that are still standing? Plenty.. But should be corrected for the reasons NEC has them in place. No need to dig into the science, just do it has been determined for reason..

 

But you can re-identify a wire as a hot to use 2 wire for equipment that only requires 240v and a ground but no neutral.

 

When this subpanel was done years ago, it was done by a certified licensed electrician.  I think at the time it was never imagined anything more than the minimal was going to be ran at or from the garage.  When i go into the cellar I can see that its indeed 10/2 with a ground (says on the wire).

And this is the wiring inside the panel in the house:

housepaneloff.jpg

 

So i'm trying to get a handle on what has been said so far here..

 

Only one grounding point should occur at the main point of the house with a copper rod correct?  If so, then wouldnt it follow that a ground does go from the main panel to the garage (or is it being suggested the metal in the garage panel itself isnt grounded)?  The thinking is that the ground is somehow acting as a neutral here? I cant imagine our original electrician would have done it this way and that issue with the 10/2 wiring that there is not a dedicated neutral (to the garage)?

 

Still also unclear on the whole electrical pvc and wiring, i was pretty sure the orange 10/2 was put in pvc, maybe not, its been awhile since that was run.

If that bar in your garage panel where the grounds and neutrals are hooked to does not have a screw contacting it to the enclosure(metal to metal) then you have an ungrounded enclosure. One thing is you could have a slit in the insulation on a "hot" wire that accidentally got cut and is in contact with the housing if it were bare metal, which some are, your're energizing a box that is just waiting for you.. Slim chance that you touch it while another part of you is grounded, then it's gonna get you! As long as your not barefoot in a puddle of water you'll likely survive.smile.gif

 

The ground is being used as a neutral, which should be corrected.

To verify if it is piped, have someone watching where it comes into panel, and tug good on the other end at house.(of course shut down the main to be safe). If piped you should at likely at least see wire wiggle a little at the other end.

 

Oh, and as far as digging.. If you take a pass along with a round nose shovel, and then go deeper bit by bit in line with the trench with a trench shovel, you can be down 2' in easy ground "somewhat" easy..

 

https://www.homedepo...wE&gclsrc=aw.ds


Edited by spacemunkee, 20 July 2019 - 09:21 PM.


#52 Rich V.

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Posted 20 July 2019 - 11:20 PM

That sub panel installation wasn't code even by the 1971 codebook; it's just plain wrong.  Are we living in Mayberry and Gomer Pyle is the town's electrician, too? 

 

Get that garage panel re-fed for 240V with three conductors w/grd to make it safe.  It should never have been done like that.  Ever.  Then you can think about what needs to be done for the observatory.  

 

Did you measure the voltage at the garage panel?  Knowing that and using the voltage drop calculator, you can determine the size wire you need to the observatory based on your intended load and the end voltage it will be happy with, which you haven't spelled out.

 

Jeez, I thought I lived out in the sticks...



#53 markm75c

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Posted 20 July 2019 - 11:39 PM

That sub panel installation wasn't code even by the 1971 codebook; it's just plain wrong.  Are we living in Mayberry and Gomer Pyle is the town's electrician, too? 

 

Get that garage panel re-fed for 240V with three conductors w/grd to make it safe.  It should never have been done like that.  Ever.  Then you can think about what needs to be done for the observatory.  

 

Did you measure the voltage at the garage panel?  Knowing that and using the voltage drop calculator, you can determine the size wire you need to the observatory based on your intended load and the end voltage it will be happy with, which you haven't spelled out.

 

Jeez, I thought I lived out in the sticks...

No idea why or how it was done like this, before my time here at least.  But i'm certainly glad i looked inside and shared the photo to come to this realization now and not the hard way.

 

Yeah i measured it off the line coming into the garage (at the garage) it was 120.1v so normal i guess in that regard.



#54 Rich V.

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Posted 21 July 2019 - 12:02 AM

 

Yeah i measured it off the line coming into the garage (at the garage) it was 120.1v so normal i guess in that regard.

That's good news, anyhow.  A single 15A circuit (2 wires + grd) on #10 copper will give you 115.5V at the obs which should be fine for most equipment.  You can always pull a second circuit and leave it spare in your obs junction box for future needs.

 

Please fix that garage sub-panel first...



#55 GrandadCast

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Posted 21 July 2019 - 06:07 AM

Your home should have just one ground and that should be at the main service from the power company at your meter loop. Ground and neutral are NOT the same and are only connected together at that main service. GFI work better this way. You should run from your main panel or where your meter loop service is located, not from a sub panel. On the observatory you should have an outside pull encase there is an issue or fire then power can be cut there or at the main. I have wired a few times and follow latest codes, but I like my insurance company to pay out and not find reasons not to. Like you I am currently building and it’s 200 feet away, however, trencher digging here has to be basically a rock saw. I don’t want to rent this for cutting through bedrock, this is hard on the blade and I don’t want to be buying parts if teeth break off. I like my insurance company so I getting the electrical company here in Wimberley do it. They wired my meter loop when the house was built last year. I am running a 60 amp circuit 240 to the observatory. Air conditioner are cheap and running them on low is a dehumidifier. I know someone who doesn’t uses his in the day time currently as it is way too hot to be in there, he regrets not running more power. You’re going to run a circuit then run one, not a glorified extension cord.

Jess



#56 markm75c

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Posted 25 July 2019 - 09:22 PM

Updates here.. thanks to all that helped get me figured out to this point:

 
Today I rented a ditch witch which the local ace place delivers.  Total cost to have delivered for 4 hours around $175 with the delivery fee i think it was.

I trenched the path from right corner of the deck.

My wiring for the observatory is NOW going to come from the main panel in the house and on 10-3 with a ground.  Cost around $1/ft for uf-b burial type (bought 130 feet), down 24" with caution tape on top (that part is now done at least).  I ran a section back to the garage to fix the mess there, will have the electrician fix the sub panel in the garage later (and just cut the old 10/2 line outside).  In the garage/house will be a junction box on the other side of the wall followed by romex cable (same 10-3 with ground to the breakers).
 
At the deck post i'm using an LB electrical conduit (1") to a plastic junction box, which from there once the dome is put on, ill run (i guess) more uf-b 10-3 at least to the 2 breaker panel ill use (i think), from there two 20 amp circuits (serious overkill as of now but i can), likely the whole breaker at the main will be 40 amp.  I'm not sure in the nexdome where i will put the panel, I see some put it on the pier (10" pvc in my case), i havent seen anyone with it on the wall inside, not sure which is less out of the way.  Then from there have 4 outlets on the pier and maybe 4 on each side of the dome on the wall somewhere.  The wiring off the panel can be 12-2 romex at that point, inside the dome, pretty sure.
 
The data is being run via electrical conduit, 1.5" for 3 gigabit Ethernet cables and one bnc cable for a camera, along with a fish rope that will be left in case more is needed in the future.  
I'm using an LB Connector box at the deck (at least i think this is how ill have the wires there, or maybe just hanging out of an open pvc pipe and bagged/weatherproofed till the dome is ready unsure.. either way ill put the gigabit in a pvc from that junction spot on the post of the deck to the inside of the dome to protect against weather (they are not outdoor cat6).   On the other end is a definite lb connector into the block at the house.

So far it appears i needed at least 10 sections of the 10 foot pvc 1.5 (roughly $6 per pipe) plus some added couplers and 90 bends.

 
I know many here have said you dont need a second grounding rod out by the dome if its protected at the main, but both the electrician and the local supply shop agreed since the dome is the highest structure in the top of the yard, despite there being a ground at the main and flowing through, that i should have a ground rod up at the deck as well.  An 8 foot cooper one along with 6 gauge copper is going to be put horizontal in the ditch up there or driven into the ground.
 
So the ditch layering is like this:
 
24" deep, first the ufb wire
Covered that with about 4" of dirt
Then laid the caution tape.
On top of this is the 1.5" pipe for data, then the rest of the dirt.


 
trench1.jpg
trench2.jpg
 
 
Back to the deck update:
 
 


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#57 Garyth64

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Posted 25 July 2019 - 10:12 PM

I had to run a ground rod at my garage when I supplied it with electricity.  It was required by the city, for what ever reason.

The rod is to be put vertically into the ground.  You want any strikes to get dispersed deep in the ground, not horizontal in the trench.

 

It sounds like it's coming together.



#58 markm75c

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Posted 25 July 2019 - 10:27 PM

I had to run a ground rod at my garage when I supplied it with electricity. It was required by the city, for what ever reason.
The rod is to be put vertically into the ground. You want any strikes to get dispersed deep in the ground, not horizontal in the trench.

It sounds like it's coming together.


Yea we are going to drive it in vertically. That makes more sense indeed.

Yep I'm getting there bit by bit
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#59 kathyastro

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Posted 26 July 2019 - 05:02 AM

I did the same with my caution tape.  I since learned that it should be near the surface.  Cable, then 18" of fill, then the caution tape, then fill the rest.



#60 HunterofPhotons

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Posted 26 July 2019 - 09:53 AM

Do you think that a ground rod at your observatory is going to dissipate a lightning strike?

 

dan k.



#61 John Fitzgerald

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Posted 26 July 2019 - 12:01 PM

Do you think that a ground rod at your observatory is going to dissipate a lightning strike?

 

dan k.

NO, DEFINITELY NOT.



#62 spacemunkee

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Posted 26 July 2019 - 12:23 PM

Have done a couple lighting preventer installs in the past year or so.

 

8' lighting rod at the highest point with I believe was a 2/0 copper ran to 3-8' ground rods 10' apart, 24" deep with the end of the wire terminating back to the house tied to the house ground. 

 

GC I work for's brother owns a lighting prevention company,  so he sells people on it and gets the kits off him. Told him I don't really care to do it after the first one cause it sucks. But then he goes and sells another! 

 

Super fun time about 40' up on backside of chimney. 

And then there's the digging...frown.gif

 

 

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#63 John Fitzgerald

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Posted 26 July 2019 - 03:50 PM

I'm going to be lengthy here, but these things were part of my specialty where I worked for over 35 years.

 

If you want to dissipate a lightning strike, a ground grid is needed.  A series of 4/0 or larger bare copper wires laid in a 4x4 foot grid pattern, about a hundred feet square (10k sq ft), buried about 2-4 feet deep.  This grid is redundantly connected near the center if possible to a heavy well casing that is in contact with groundwater.  A heavy copper lead or leads from near the center of said grid is connected to whatever you want to protect above ground.   A series of large bare shield wires (usually galvanized steel cables) is also connected to the grid and run over the top of the protected structure on poles or towers. 

Sometimes a lightning mast is also employed and connected to the ground grid.  This is real lightning protection, but in the event of a large bolt, this will even partially fail, and the damage will be only limited, not eliminated.   

Lightning arresters on neighborhood distribution poles are designed to send a pulse to ground only when the voltage exceeds 125% of the nominal line voltage, which could be anywhere from 5kV to 18 kv.  Not designed to protect your house, but designed to protect the distribution system.  

 

A ground rod by itself is only "feel better" protection from lightning.  Ground rods in residential are only to eliminate "stray voltage" seeking ground, and may mitigate shocks, and enhance the tripping of overloaded circuits or GFCIs when a ground fault occurs.


Edited by John Fitzgerald, 26 July 2019 - 03:52 PM.


#64 spacemunkee

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Posted 26 July 2019 - 05:15 PM

Yeah, I wouldn't exactly put faith in what I installed. But you wanna pay for it, fine. Just did as I was told with what I was given. 

After that its in gods hands.lol.gif 



#65 greenstars3

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Posted 27 July 2019 - 11:36 PM

One thing you can not do is have  a concealed electrical box anywhere in the system - they must be accessible or it will be a code violation and will be seen by prospective buyers as funky stuff and fail an inspection, you can look online or get local codes. Most local jurisdictions use the National Electric Code as the standard for both installation and inspection, if you are not sure get advise from an electrician. Some jurisdictions let you wire up your own stuff but when you go to sell the place the issues will come to the fore.

 

Robert 


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#66 markm75c

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Posted 28 July 2019 - 12:39 AM

One thing you can not do is have  a concealed electrical box anywhere in the system - they must be accessible or it will be a code violation and will be seen by prospective buyers as funky stuff and fail an inspection, you can look online or get local codes. Most local jurisdictions use the National Electric Code as the standard for both installation and inspection, if you are not sure get advise from an electrician. Some jurisdictions let you wire up your own stuff but when you go to sell the place the issues will come to the fore.

 

Robert 

What do you mean by concealed electrical box exactly?



#67 kathyastro

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Posted 28 July 2019 - 06:36 AM

What do you mean by concealed electrical box exactly?

A junction box that is above a ceiling, below a floor, behind a wall, behind a cabinet, etc. is concealed and therefore a code violation.  All junction boxes must be visible and accessible.  Behind movable furniture is okay.


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