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

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#26 John Fitzgerald

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Posted 19 July 2019 - 07:52 AM

In at least some localities, when a buried electrical run is done to an otherwise so called portable outbuilding, it becomes a permanent installation, requiring permitting.  That’s the way it is here.



#27 markm75c

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Posted 19 July 2019 - 08:41 AM

One of the things that needs to be considered when running power to an observatory is, "how much power do I need". People doing imaging with a portable rig can easily do a full night's work using an 85AH 12V battery. If we make worse case assumptions, using all of the battery capacity over ten hours, that's 1000W or 100W/hour. Since power will be brought into the observatory at 120V, that's less than 1A! The only things you might use in an observatory that would significantly increase power consumption would be an air conditioner or an electric heater.

 

A simpler, less costly, solution if you will not be using these high current devices would be to run #10 wire to the observatory and install a 10A breaker feeding it. I suspect you'd have enough power to run an 800W electric heater, even with the 10A breaker.

 

An interesting alternative, possible because almost all astronomy gear runs on 12V DC, is to use an RV converter to keep a deep cycle battery charged and provide DC power to the equipment. Use a DC motor for the roof and you'll never have to worry about a power failure interrupting your observing and preventing you from closing the roof. If you have some gear that requires other DC voltages, DC-DC switching voltage converters are available that can provide both higher and lower voltages from a 12V source. These regulators are usually more than 90% efficient which means that a 5V regulator feeding 2A of current to USB devices (10W) will draw less than 1A from the 12V battery. An older style linear regulator supplying the same voltage and amperage would draw 2A (24W) from the battery and have to dissipate 14W of power as heat.

I think with my laptop at least and my old 8se alt/az mount (going to the cem120) i was pulling maybe 4-5 amps.

 

So i'd guess with a NUC and little bit extra maybe 6 at best.

 

Then the AC unit, if i ever add one, not sure what btu, but 8000 btu is around 6.5 amps from what i looked up.

Or

If using a dehumidifier it might be 3-4 amps for a small one.

 

Then there is the small heater, 2-3 amps max?

 

In all here with going with the AC not dehumidifier worst case, i think? maybe 15 amps, so to be safe a 20 amp breaker?  My pool doesnt run at night so that would probably never be a factor with its 9 amps and the lights/garage door opener mostly a non factor on that full 30 amp capacity on the garage breaker, in theory.

 

The question is, would it be more ideal to run that 240 to have separate circuits, isolating the heater and ac/dehumid unit on their own?  If its not a big deal then I'd go the simple route, 8 or 10 gauge wire provided the distance doesnt cause too much drop (ill need to revisit those stats above)

 

**I have a contractor relative and electrician contacts, id ideally just want to run the right type of wire in the ground and have it ready then have an electrician check and validate things


Edited by markm75c, 19 July 2019 - 11:02 AM.


#28 Garyth64

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Posted 19 July 2019 - 08:41 AM

I re-read your initial post, and saw that you are wanting to power the observatory from your garage.  The garage has a 30amp breaker. 

Where is the power to the garage coming from?  If it's coming from the house, how long is that run?  What is that size of the wire going into the garage?  And now you want to extend that line to the observatory.  You may be limiting yourself.

You may get a voltage drop from the length, as mentioned.  Things will still work, but may have their lives shortened from overheating.

 

As I said, plan for the future.  Will you want a heater out there? or an AC?   I looked at your other thread, is the dome going to be motorized?  How many computers could end up out there?  Will you want any exterior lighting on the building?

How about a radio? a refrigerator? etc.  Exterior outlets?  Printer? Security system? etc.

 

I wish I was faced with these thoughts on building an observatory. smile.gif


Edited by Garyth64, 19 July 2019 - 09:46 AM.


#29 spacemunkee

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Posted 19 July 2019 - 08:47 AM

Cause we all know without paying those fees and having it looked at, it's guaranteed to burst into flames even though it's a proper installation. :)

What they don't know won't hurt, unless you have one of those neighbors that are just looking out for everyone's safety.

A buddy has one of those. When he was doing some not so major stuff on his old place, of which he's well capable and qualified, I said really, you're dealing with inspections?

Said he had one of those neighbors that would be calling the proper authorities if he heard a nail being driven. And had done so to several around him.

Mind your own dang business!

#30 HunterofPhotons

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Posted 19 July 2019 - 10:37 AM

It's obvious that the original poster doesn't even have a rudimentary knowledge of electrical installation.

Messing up the electrical stuff in a construction project can have serious consequences like fires and even less serious consequences like low voltages, ground loops, etc.

These are the types of scenarios where building inspectors actually perform a valuable function, protecting people from themselves and their unwise mistakes.

If the OP doesn't want to get his work inspected or spend the money to hire an electrician he would do well to at least get someone knowledgeable to look over his work before he 'fires' it up.

 

dan k.


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#31 Garyth64

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Posted 19 July 2019 - 11:28 AM

"At first i thought i'd bring the two conduits up near the edge of where the inner side of the dome wall will be, but since i dont know that, i'm thinking ill route it to the pier location, next to it, on a vertical piece of pvc coming up."

 

I would bring your data line, and your power line, up to the outside of the observatory wall, and then pipe them in.  The power panel would be on the inside of the wall, and from there to any outlets, lights, and the pier.

The data line would go to a splitter, where one runs to the pier, and the other to maybe a desk where a computer would be located.

Anything to the pier could be run under the floor.  This should be ok since the pier is separated from the floor anyway.

 

You also want to have everything easily accessible in case you have to modify any of the wiring.


Edited by Garyth64, 19 July 2019 - 11:29 AM.


#32 spacemunkee

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Posted 19 July 2019 - 11:59 AM

It's obvious that the original poster doesn't even have a rudimentary knowledge of electrical installation.
Messing up the electrical stuff in a construction project can have serious consequences like fires and even less serious consequences like low voltages, ground loops, etc.
These are the types of scenarios where building inspectors actually perform a valuable function, protecting people from themselves and their unwise mistakes.
If the OP doesn't want to get his work inspected or spend the money to hire an electrician he would do well to at least get someone knowledgeable to look over his work before he 'fires' it up.

dan k.


Absolutely agree on having things checked out by someone knowledgeable if you're unsure of yourself. But I feel the OP has the skills and the sense to be able to figure it out. Then there's some people that probably shouldn't even install a cover plate.

There's plenty of free knowledge on the net to be able to school yourself properly to make sure your installation is correct and safe. But still maybe throw someone a few bucks to give you some guidance and look things over.

Inspectors I deal with on a regular basis don't dig deep. Give a whole house about 5-10 minutes tops. They're not checking how well made your connections are and such. Pretty much yep, looks done, correct breakers, gfci's, etc..

Hell one has came in before, walked around for a minute, maybe checked an outlet or two and handed me my tag. But then again they've known me for years.

I just happened to talk to the chief inspector here a few days ago to question him on what I already was sure of. GC wants me to do a small job which is considered commercial, but knew you had to hold a contractor's license for it here. Was just confirming. As of present there is no licensing requirement to do residential work in Ohio, but there working on implementing it.

Even he said it's all about the money. Straight from the horses mouth...
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#33 markm75c

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Posted 19 July 2019 - 09:17 PM

"At first i thought i'd bring the two conduits up near the edge of where the inner side of the dome wall will be, but since i dont know that, i'm thinking ill route it to the pier location, next to it, on a vertical piece of pvc coming up."
 
I would bring your data line, and your power line, up to the outside of the observatory wall, and then pipe them in.  The power panel would be on the inside of the wall, and from there to any outlets, lights, and the pier.
The data line would go to a splitter, where one runs to the pier, and the other to maybe a desk where a computer would be located.
Anything to the pier could be run under the floor.  This should be ok since the pier is separated from the floor anyway.
 
You also want to have everything easily accessible in case you have to modify any of the wiring.


The issue is, if i do the power runs and data now, before the dome is on the deck (eta 2 months), then i really dont know where things will be, ie: i could be putting it on one side where i'd rather have one of the two bays or maybe its off a bit.

Thats why i thought maybe i should run everything to the pier instead?

Or, i guess i'm forced to wait till i get the dome in place and make sure somehow i have removable 5/4 boards here and there to be able to have multiple options on pathways.

On the data, i'm going to run 3, cat6 cables, i might only use one for now, but yes i might probably just put a switch off the main line and split to whereever i need it.

#34 markm75c

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Posted 19 July 2019 - 09:19 PM

It's obvious that the original poster doesn't even have a rudimentary knowledge of electrical installation.
Messing up the electrical stuff in a construction project can have serious consequences like fires and even less serious consequences like low voltages, ground loops, etc.
These are the types of scenarios where building inspectors actually perform a valuable function, protecting people from themselves and their unwise mistakes.
If the OP doesn't want to get his work inspected or spend the money to hire an electrician he would do well to at least get someone knowledgeable to look over his work before he 'fires' it up.
 
dan k.


Ill be in contact with an semi retired electrician who is going to give me some advice on what to do and probably come take a look. In the end before powering on, ill at least make sure everything is properly done and/or get a full blown electrician to come and give it a final comb over and/or even do the final wiring on each end.

And like i said, i previously had a person helping me do wiring to our pool deck area and it worked out fine, but that was basic 12/2 wiring. Some of the other wiring being discussed here i havent encountered (yet) like the 240 option or the aluminum.

#35 markm75c

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Posted 19 July 2019 - 09:25 PM

Mark, the OP, hasn't said what his line voltage actually measures; if it starts out at 120V and he's pulling say, a 15A load, #8 copper or #6 aluminum will give him 117.2V at his observatory.  If he goes with #10 copper, it's down to 115.5v.
 
What voltage delivered at the observatory will be adequate for his equipment?  I can't say.  There are online calculators that figure this anymore; not like when I was an electrician apprentice many years ago and we had to do it manually.  wink.gif
 
http://wiresizecalcu...voltagedrop.htm
 
The original line voltage matters a lot; take your pick; I did the hypo calculations for Mark-
 
A 20A load @ 120V with #8 cu would deliver 116.25V or with #10, 114V.
- 15A load: 117.2V or 115.5V, respectively
- 10A load: 118V or 117V
 
If the line voltage is only 115v, though:
- 20A load: 111.25V or 109V
- 15A load: 112.2V or 110.5
- 10A load: 113.1V or 112V
 
You see there is a real potential to have significantly low voltage but there are a number of variables; line voltage, load and wire size matter.
 
I agree that using aluminum wire in the larger sizes saves a lot of money as long as the wire is terminated properly.


It sounds like at least #8 (8/2?) wire is the best bet, or the aluminum #6 i guess.  I'm not sure what the voltage requirements are when it comes to say 117.2 vs even 111.5 (i guess with the cem120 its 12v based so it should be fine), probably even the small pc or laptop too, maybe thats only an issue with an AC unit if i ever use one.

 

So would it be ideal to measure the voltage at the subpanel in the garage somehow first? See what voltage that is (i have a multimeter).  The garage is about 40-50 feet from the main panel in the cellar of the house.

 

Still debating if i should have 240 line for separate circuit isolating a dehumidifier/fan/ac from the pc/mount and equipment?

 

EDIT: checked the house's main breaker switch, it has 100 on the breaker switch so i guess the whole system as of now is only 100, surprising as there are lots of 15 and 20s on the main house panel, but obviously not pulling the full loads.  The breaker labelled garage of course says 30, which is what the sub panel is labelled with in the garage with its 3 of 4 current breakers (one lights, one outlets, one pool)


Edited by markm75c, 19 July 2019 - 09:29 PM.


#36 Garyth64

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Posted 20 July 2019 - 07:49 AM

If you have a 12/2 running from your house to the garage, to a 30amp breaker over 50', and you want to run another 120' using #8 wire to the observatory.  I don't think you can do that.  You are limited by the size of the wire going from the house to the garage.  That is the weak link.

 

You will not be able to run a 240 line from the garage to the observatory, because you don't have 240 going into the garage.

Maybe you could just by-pass the garage, and run the size wire you need directly from the house to the observatory.  But you may not have enough room in the house panel to do that.

 

After hearing how you have everything set up, you may be restricted to running another 12/2 wire from the garage to the observatory, and keep everything in the observatory to a bare minimum.  You would be doing a lot of work, and end up with something you may not be satisfied with.



#37 spacemunkee

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Posted 20 July 2019 - 08:58 AM

Yes, if you have a meter then check what you got. Just test from the hot lug feeding the bus bar to neutral/ground bar. If your getting somewhere around 120v then you're good. If getting down around 110v, then you're pushing it and should keep that new run a bit more oversized to try and keep from dropping much more.

 

Properly wired 240v sub-panel should look like this. 

Screenshot_20190720-092946_Google.jpg

 

Testing across both the hot lugs will give you your 240v reading. If you only see one hot wire hooked to a lug with just a jumper wire between the two, then whoever only wired it for 120v.

 

Could post a picture of the inside of that panel so folks can see what you got. 

 

As far as your main service max, adding up the breakers is usually always going to far exceed your main number. It really comes down to doing a load calculation for the residence which is based on square footage, and your large draws such as range, water heater, electric furnace, AC. Little more to it,  but that's the basic idea. 

 

 

 


Edited by spacemunkee, 20 July 2019 - 08:59 AM.

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#38 Rich V.

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Posted 20 July 2019 - 10:00 AM

 

So would it be ideal to measure the voltage at the subpanel in the garage somehow first? See what voltage that is (i have a multimeter).  The garage is about 40-50 feet from the main panel in the cellar of the house.

 

Still debating if i should have 240 line for separate circuit isolating a dehumidifier/fan/ac from the pc/mount and equipment?

 

Mark, you really need to verify that the 30A garage sub panel is wired with at least #10 wire as it should be.  I'm hoping it's wired like shown in the picture Spacemunkee posted above.  That sub panel will have its own voltage drop from the main panel so turn on the normal nighttime load for that panel and measure the voltage as Spacemunkee suggests.  This is the voltage you'll be starting out with before you figure the voltage drop you'll have 120' further out at your observatory.  You need to know this voltage first so you can calculate your final observatory voltage.

 

You can then determine what voltage at the obs you end up with using the voltage drop calculator. You can decide then whether it will be sufficient for the various equipment you'll be running. 

 

Let us know what turns up...



#39 John Fitzgerald

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Posted 20 July 2019 - 10:53 AM

I would just run #12 UF/G to the observatory.   In reality, your load will rarely, if ever, exceed 2 or 3 amps.  At that level, the voltage drop will be low.  Even if you run a hair dryer on rare occasions to clear off dew or frost, it won't hurt a hair dryer to run on lower voltage; it simply won't heat as much.

 

My Exploradome is about 45 feet behind the garage (southeast side), which is part of the house.  My garage is served by a 60 amp sub panel on the NW side of the garage.  A #12 (20 amp) GFCI protected circuit runs along the back wall of the garage, then along the east wall, terminating in an outside outlet 45 feet north of the observatory.  A 50 foot #14 outdoor cord runs along the very edge of the driveway next to a retaining wall from that outlet to the observatory, and is plugged into a box on the outside of the observatory that serves one duplex outlet directly inside.  That is all I have needed in almost ten years of having the observatory.  It runs a 47 watt (0.4 amp) exhaust fan on a thermostat for cooling, and a 40 watt bulb under the scope cover when needed for moisture protection (not simultaneously).  The scope power supply itself uses less than 1/2 amp.

 

On rare occasions, I have run a 1200 watt hair dryer in there to dry the top of the scope before covering it for the night.  No problems doing that either.

 

Bottom line, unless using an a/c in the dome (unnecessary and expensive IMO), the power requirements for a small dome are very minimal.

 

This project is being overthought, and over engineered, IMO, unless (expensive to run) A/C is contemplated.  A ducted exhaust fan should be plenty to prevent heat buildup.


Edited by John Fitzgerald, 20 July 2019 - 04:46 PM.


#40 Garyth64

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Posted 20 July 2019 - 11:21 AM

"This project is being overthought,"

 

and without all the facts, not knowing what is there originally, simple and accurate advice is difficult.


Edited by Garyth64, 20 July 2019 - 11:23 AM.

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#41 Rich V.

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Posted 20 July 2019 - 11:58 AM

"This project is being overthought,"

 

and without all the facts, not knowing what is there originally, simple and accurate advice is difficult.

Exactly.  After 40 posts we still know little about the particulars.  It's simple Ohm's Law but only a logical process  based on fact can determine what is needed.

 

Any qualified electrician could look at the situation in person and figure a proper solution in a few minutes.


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#42 spacemunkee

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Posted 20 July 2019 - 11:59 AM

I agree it's being overthought a bit and the actual draw will be minimal unless adding AC or some other good draw.  

 

I still say just throw in some decent size aluminum for less than what you'll give for that copper to future proof for that "just in case".

 

As far as ventilation, I just have two of these from Home Depot.  1 high in one corner on the east side so the midday/ evening sun isn't beating on it outside drawing in, and 1 low opposite side corner drawing out. Does well enough for my little 8' x 8'.

Screenshot_20190720-123244_Home Depot.jpg

 

 

Another thought,  just throwing it out there. 

From your pic in the other thread I don't see a meter on the side of the house facing garage. I assume your main panel is on opposite? 

 

But if you have a junction box on that side of the house where the garage wire possibly junctions over from indoor to underground wire, you could trench to there, splitbolt splice into it there and out to small sub at obs. That way for that "just in case", you could always separate and extend back to main panel. 

 

But just overthinking things here! :)



#43 markm75c

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Posted 20 July 2019 - 03:10 PM

Ok everyone i have some updates finally..

 

First off here are some shots of the panels..

 

The house panel is here: (100 amp main breaker as of now)

housepanel.jpg

 

The garage panel is here: (240 v feed confirmed finally)

Thanks for showing how to test the volts, i got a reading of 120.1v, so thats good.  I cant tell from the wire coming in (orange) if its 10 or not, it should be though, the wiring going to my pool is 12/2 i think.

The run to the pool comes in here as well, it just runs along the wall in the garage down low then through the wood wall of the garage outside then down 2 feet underground and back up to the deck of the pool into the gfci outlet (the first one of 3 being gfci)

garagepanel.jpg

 

Then I got on the phone with an electrician contact, semi retired, but he gave me lots of input.

 

The first thing i found odd was that he said UF-B type romex cable cant be put in conduit, its illegal he said, i guess only "stranded"? can (Thhn?)? (although you can use conduit where it comes up out of the ground and goes to a wall)

 

He recommended to future proof in case i do in fact want to run an AC unit up there is to do 8/3 with ground (which will allow for 240 later) which will cover up to 30amp?  The 8/3/g should have B, R, W and copper.

Otherwise just 8/3 without ground or even 10/3 if only ever doing 20amp.

 

He said just to lay it in the trench, maybe cover with 6" of dirt then i can have my 1 or 1.5" pvc (grey still i think) for the 3 gigabit cat6 lines i'm going to run at the same time.

 

He mentioned about doing the 8' copper rod (where do you find the rod?), just laying it in the trench up near the observatory.

 

It was suggested since i dont really know where the wall or spot i'd put a panel in the garage would be, just to have the wires come up at the corner of the deck (for now?) into a junction box that is water proof.

I'm not sure i understand how to tie into the copper rod just yet, didnt have to do that with a simple 12/2 run to the pool last time, it was just panel to the gfci standard outlet wiring which was easy.

 

He mentioned since its a 240 circuit that every other breaker should be its own isolated phase in the garage too.  I guess that could offer a thought or two on maybe having the ac part of the circuit there on one phase and the rest for the telescope/laptop isolated.

He also said he'd drop by when i'm ready to run things and give it a look over or help with wiring on each end (goal here for now just get the right wire in the ground coming out at each end and go from there)


Edited by markm75c, 20 July 2019 - 03:20 PM.

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#44 spacemunkee

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Posted 20 July 2019 - 03:44 PM

Was afraid I'd see that. That sub panel will "work" but it's not "correct". It's only 2 wire with ground which is being used to carry neutral and ground when it should look as picture I posted. Neutral should be separated and isolated from enclosure(panel box) and grounds should be bonded to the enclosure.

And so as yours appears, you have an ungrounded metal enclosure. As far as the run to obs, if running 240 to a sub there, having 2 hots a neutral and using a ground rod isn't right. Should be a dedicated non-current carrying ground all the way back to main service. And that's an oddly setup box it appears. Top two slots capable of a 2 pole 240 breaker being each hot is a slot there. The bottom two just look to be connected to that one hot so can only be single pole breakers.

And yes you can put uf in pipe, just not standard "romex" indoor wire. Only issues with pipe to meet code is you can only cram so many wires in(according to wire size/ pipe size).

Orange wire 10-2, yellow 12-2, white 14-2, grey is a uf, looks like 12.

If that orange is ran completely from house to correct, that's indoor only wire, not made for burial. Sure it will work, but over a long while it will begin to deteriorate in contact with moisture in the ground.

That being said, if it were me, I'd be coming straight off the house, 4 wires to a little panel.

And the pool wouldn't need a rod, but the metal frame should be properly bonded to the pump housing which is grounded back through feed wire. There's a whole chapter in the NEC on pools and spas, and for good reason..

Rarely dealt with pools, but one I wired up a few years ago like yours, code called for a perimeter bond, which was a run of bare copper about 6 inches down all the way around the pool bonded to the frame at so many intervals tied to the ground lug on the motor housing.

Edited by spacemunkee, 20 July 2019 - 04:10 PM.

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#45 John Fitzgerald

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Posted 20 July 2019 - 04:49 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.


Edited by John Fitzgerald, 20 July 2019 - 05:28 PM.


#46 John Fitzgerald

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Posted 20 July 2019 - 05:35 PM

Ok everyone i have some updates finally..

 

First off here are some shots of the panels..

 

The house panel is here: (100 amp main breaker as of now)

housepanel.jpg

 

The garage panel is here: (240 v feed confirmed finally)

Thanks for showing how to test the volts, i got a reading of 120.1v, so thats good.  I cant tell from the wire coming in (orange) if its 10 or not, it should be though, the wiring going to my pool is 12/2 i think.

The run to the pool comes in here as well, it just runs along the wall in the garage down low then through the wood wall of the garage outside then down 2 feet underground and back up to the deck of the pool into the gfci outlet (the first one of 3 being gfci)

garagepanel.jpg

 

Then I got on the phone with an electrician contact, semi retired, but he gave me lots of input.

 

The first thing i found odd was that he said UF-B type romex cable cant be put in conduit, its illegal he said, i guess only "stranded"? can (Thhn?)? (although you can use conduit where it comes up out of the ground and goes to a wall)

 

He recommended to future proof in case i do in fact want to run an AC unit up there is to do 8/3 with ground (which will allow for 240 later) which will cover up to 30amp?  The 8/3/g should have B, R, W and copper.

Otherwise just 8/3 without ground or even 10/3 if only ever doing 20amp.

 

He said just to lay it in the trench, maybe cover with 6" of dirt then i can have my 1 or 1.5" pvc (grey still i think) for the 3 gigabit cat6 lines i'm going to run at the same time.

 

He mentioned about doing the 8' copper rod (where do you find the rod?), just laying it in the trench up near the observatory.

 

It was suggested since i dont really know where the wall or spot i'd put a panel in the garage would be, just to have the wires come up at the corner of the deck (for now?) into a junction box that is water proof.

I'm not sure i understand how to tie into the copper rod just yet, didnt have to do that with a simple 12/2 run to the pool last time, it was just panel to the gfci standard outlet wiring which was easy.

 

He mentioned since its a 240 circuit that every other breaker should be its own isolated phase in the garage too.  I guess that could offer a thought or two on maybe having the ac part of the circuit there on one phase and the rest for the telescope/laptop isolated.

He also said he'd drop by when i'm ready to run things and give it a look over or help with wiring on each end (goal here for now just get the right wire in the ground coming out at each end and go from there)

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.


Edited by John Fitzgerald, 20 July 2019 - 05:36 PM.


#47 Rich V.

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Posted 20 July 2019 - 05:38 PM

Bad news on that garage sub panel; two "hots" and a ground but no neutral conductor; a total red flag.  frown.gif   The ground wire is never intended to be a current carrying conductor. Should have been three wire w/ground, not two wire.  Black, red, white and a ground.  No real electrician would do it this way; it must have been a DIY homeowner project done without an understanding of safe electrical practice.

 

Jacketed underground feeder cable is generally not pulled into conduit; it's made for direct burial.  It's terribly hard to pull into conduit around elbows.  That's why they make single conductor building wire. IIRC, DB cable must be buried at least 24"; PVC conduit at least 18" depending on the location.  A licensed electrician will know how deep to put it for your location.

 

No, No, No on the ground rod.  Only the main house panel should have the neutral (white grounded conductor) bonded to the system grounding conductor (ground rod or foundation ground).  Grounding in two locations is dangerous.  I cannot recommend doing that at all.

 

I'd sure consider getting that garage panel re-fed properly with the correct number of conductors first.  You should get a licensed electrician to do the job right as your installation is clearly sub standard and dangerous.  I wouldn't use your semi-retired guy to do your work if he thinks like this.  Get a guy that knows what he's doing before someone gets hurt.   


Edited by Rich V., 20 July 2019 - 05:54 PM.

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#48 markm75c

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Posted 20 July 2019 - 06:16 PM

When this subpanel was done years ago, it was done by a certified licensed electrician (probably around 2001 maybe codes were ridiculously lax then?).  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).  Not sure if the fact it comes from a 240 breaker makes a difference though.

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)?  edit: clearly must be related to the age of when all this was wired.

 

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.


Edited by markm75c, 20 July 2019 - 06:40 PM.


#49 John Fitzgerald

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Posted 20 July 2019 - 07:37 PM

Those color codes started around 2001.  I don't think that your garage wiring was legal then.  I built a house in 1998, and the 4 wire system for two pole breakers was in effect then.  Feeder from a two pole breaker had to have black, red, white, and bare in a type NM or UF cable.  Even our dryer plug had to be 4 wire. 

 

If the orange #10 wire was put in PVC, you could pull in new wire with it as you pull it out.


Edited by John Fitzgerald, 20 July 2019 - 07:39 PM.


#50 markm75c

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Posted 20 July 2019 - 08:52 PM

Still pretty frustrating it was done wrong.  Most likely done wrong before i moved in, back when my grandparents owned the place.  Not sure why the electrician did it this way.  Now it could be costly to redo.  

 

But looking ahead to at least plan on the right wire for the observatory (meanwhile ill be getting the line fixed, nothing connected new until after), i guess i need to decide on the best wire type, guessing that still might be 8/3 with ground and should cover the need for an AC (though i highly doubt ill need one if i have an exhaust fan and dehumidifier, though who knows on a day like today, 96F in the nexdome, who knows how hot it would have been).




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