Electrician Question - Connecting detached garage
 

My parents have 2 electrical meters and pay the monthly connection fee on both meters, but the property only has 1 habitable house (house2)

Attached shows the current electrical connections in yellow, and the proposed connection in orange, with the idea to eventually eliminate the House1 meter and electric service.

My question is, what type and gauge of wire should be run from house2 to the garage 100 ft away? There's already a 1" buried conduit running from the house2 panel to the garage. BTW, the garage is used as a shop, so 240v is needed for a compressor.

Can we run house2 > garage > barn from the house2 service panel, about 400 ft total? The barn electrical requirements are minimal, just needing 120v for minimal lighting and an outlet.

I'm pitching the project to my parents as a way to reduce the monthly connection fee for the redundant service, but my interest is for everything to be electrically connected so I can run data over electrical for surveillance cameras.

Just realized this should probably live in the DIY forum.

Before you start are both services 200 amp and are you with PGE or someone else?

Speaking to the wire choice: when I ran power to my garage for my L2 charger, it was approximately 75 feet between the existing panel and the new sub panel. I used 10 gauge rated for direct bury. I read a few places that even in conduit it had to be direct bury rated, I forget the industry spec. With 10 gauge I'm good up to 30 amps at 100', it was a compromise, I really should have gone with 8 gauge.

So it really depends how much load you're going to have. Also, my project was diy and it still cost me around $2-300 iirc. It may be cheaper to just keep both services.

It all depends on the air compressor.
The minimum you should run a few hundred feet is 10 gauge.

The max you can run in 1 inch conduit is three current carries in 4 gauge and a smaller ground. 4 gauge will limit you to around 70 amps at 100 feet.

Direct burial wire is UF-B.

I'm not certain what house1 service is, but house2 is very likely 200A since it was installed just 10 years ago. House1 was built in the 19th century, so who knows when the last time service was upgraded. It has a fuse box instead of a breaker panel. The utility is PGE.

We've got a section of direct burial 10/3+G that is probably long enough, so maybe it's best to just use that. I doubt we need more than 30A to the garage. I should find out what is already running from house1 to the garage.

I'll have to look at what breakers are in there already. There's no sub-panel, and I don't know if one is required by code. We might have a sub-panel available though if one is needed.

So, if we run 10 gauge to the garage, can we also keep the existing run to the barn? As it is, I think it's just a single outlet running to the fuse panel of house1. Probably 10 gauge running to the barn, as that would explain how we have a leftover section. It's direct buried at 3 ft with no conduit. An online calculator says 10 gauge 120v at 400 ft has a 13v drop at 15 amps. That seems acceptable for a single outlet providing minimal lighting.

I know it's a big no-no, but I'm going to try running cat5 in the same 1" conduit to the garage. Don't need a lot of bandwidth, just 2 PoE IP cams. If it sucks, I might try shielded cat6.

I think I see better what you're after. I would put in the sub panel in the garage and also drop another ground rod at the panel, it will actually benefit the main service by having a 2nd ground separated by some distance.

Now, I can just about promise it would not meet code but yes, I believe you can feed power back to house 1 then on to the barn from the new sub panel in the garage.

Kinda don't care about code beyond the garage. Won't be selling the property in the foreseeable future, and the wiring was always makeshift.

That old house had the fixtures with pull chains on the sockets, along with an outlet. My dad routed strings through eye screws to these sockets so we could turn lights on where entrances were rather than having to walk to the socket to turn them on.

https://images.homedepot-static.com/...05-64_1000.jpg

So, it sounds like the project cost might be nothing if the section of 10 gauge can be used in the existing conduit, and assuming we've already got a sub panel. I'm sure we've got a spare ground rod laying around somewhere too.

So, if 10 gauge is acceptable for 30 amp service at 100 ft distance, does that mean I use a 30 amp breaker in the house2 main panel?

A lot of places require a grounding point at each structure with a panel.
A 30 amp breaker should be fine for 100 feet.

My opinion is worthless, but I will note that my VW mechanic moved shop and when he ran power underground to his new building, the inspectors made him pull up ~100ft of aluminum wire and replace it with copper. So there is that.

Weird, I wonder why? As far as I know, aluminum meets code but just requires a larger gauge since it isn't as conductive as copper.

Inspectors would have a problem with everything related to the original house and run to the barn. The barn run was cut when an excavator graded a patch of land, and it's been repaired several times and no longer sits at 3ft deep.

I'll confirm all the wire sizes and service ratings when I pick my girl up tonight.

Inspectors generally don't like aluminium.
I dont use aluminum just so they don't take a closer look.
When they see aluminum they always take a closer look. At everything.

Well, I don't like government inspectors, so I guess that makes us even.

Funny how there's no rules about balancing a bucket of knives on the edge of a ladder above living areas, but there's opinions that have the effect of law against aluminum wire.

Something terribly wrong with paying someone else to get permission to do something on your own property.

Now, the type of inspectors you pay because you truly want their expertise on the quality of something I have great respect for.

All power distribution goes over aluminum lines, the wires from the power company to your service drop are likely aluminum.
The problem with aluminum wire is the junction points. Improper termination, splicing, non conducive aluminum oxide film on all wire exposed to the atmosphere and aluminums low melting point made it dangerous. It burned down a lot of homes in the 1970s and 1980s.

I took some photos and checked out specs on what's currently installed. It's way more crackpot than I had realized, so meeting code from house2 to the garage hardly matters.

house2 (new house) has 200 amp service on a pole at the corner nearest the garage, and the 1" conduit is already in place with a pull string (bailing twine). I think I just install a 30 amp breaker in this exterior panel and run my 10/3 UF-B to it.

house1 Has 100 amp service. Check out the photos to see how jenky it is. I think the siding of the house is just asphalt shingles. Didn't seem like a crapshack when I was growing up.

The garage currently has a 20a 240v and 15a 120v breaker fed by 10/3 from the old house. I guess that wire is spec'd to 30a.

The barn has the same 10/3 wire running from the old house to a switch, which then feeds 2 light bulbs and 2 receptacle boxes.

Here's the rub, the old house has separate circuits running to the garage and to the barn, so you can run max load at any location without affecting the usable load at any other location.

If I feed everything in series from new house, to garage, to barn from a single 10/3 line, then concurrent loads all add to the 30a limit. Not a huge deal since the barn is rarely used, and has very small loads.

Now, do I pull the cable with the bailing twine, use a heavier yellow poly rope, or see if I've got a fish tape long enough?

Expect the bailing twine to barely pull a heavier rope. Fairly straight runs aren't that hard to pull, but need a puller and a helper that can straighten and push/feed. Yellow wire grease is awesome but pricey.

Now I'm thinking to purchase and pull 10 gauge THWN along with the UF-B. The reasoning is that any short or excessive electrical draw anywhere within the series of loads will trip the breaker. The run to the barn was cut when land was graded, and over the years has shorted several times and needed to be repaired. I'd hate for a short somewhere in the jenky wiring to knock out power to the garage until it gets repaired.

So, UF-B to the garage on a 30 amp breaker, and an additional 2 strands (only need 120v) THWN 10 gauge run from another 30 amp breaker to the old house/barn.

My question is, what is the danger in being completely cheap and running a single hot line from the new house to the old one, and relying on the neutral/ground of the old house? Is there a reason the grounds need to be connected by a wire?

It is possible to get a potential difference between buildings caused by grounding impedance. The tie wire bleeds that off. Could be as high as 50 -100 volts and wouldn't be stopped by flipping breaker off. So grabbing the neutral could be interesting.

Ask me how I know

Yeah, you may end up with 90 volts or 150 volts. Who knows

You have an existing breaker box in the garage? So, just tie that to the new run from the new house, run power out to the old house and barn from the panel in the garage on a 15 or 20 amp breaker so it will trip (hopefully) before the breaker at the new house?

That certainly would work. In the 3rd attached image above, it shows the breaker panel in the garage, and it looks like there is room for 1 more breaker.

That said, If I can run 2 strands of THWN for say $35, it might make more sense as it also doubles the capacity that can be simultaneously used.

Rant- My dad has a 2nd deep freezer in the old house; the other one is in the garage. Then he has 2 giant refrigerators in the house with freezers. My mom and dad live there. Anytime someone gives him something, he thinks he has to use it. His friend just gave him an electric shop heater and he's asking me to wire in a circuit for it even though he's already got propane heaters.

Someone made off with my jetski and trailer, which is the final straw that is pushing me to install security cameras, but I wouldn't mind if thieves would make off with some of the junk lying around. Perhaps a spare tractor, some heaters or freezers...

The junk lures them in and then they take the good stuff.

What you're doing is beyond the scope of this solution, but when my father wanted power for lights in a detached garage, he put a male plug on both ends of a 50ft extension cord, then plugged one end in in the house and the other in the garage.

Silverton lost power today for about 6 hours. Was thinking I might grab my dad's generator and run it on the balcony of the apt to keep the food cold. Then I found out PGE posts the ETA of repair on their website.

If you dont open them much, and fridges are fairly full, they stay resonably cold for about 2-3 days. Full freezers are good for almost a week.

Hoarding stuff is a natural part of aging. Unless I stop myself, i'd have a fridge full of leftovers.

I'll bet you have a phone just chock full of pictures

Our freezer was pretty full, so it seemed to stay cool. I BBQ'd cheese burgers on the deck last night, and we ate by candle light.

I toured a home for sale while the power was out, so we were all walking around with our cell phone lights on. There was still daylight left and most of the rooms had plenty of light. I despise HOAs though.

...It should be sufficient to run hot and neutral between new house and old house, right? That would bond the grounds at least, so I can't imagine needing a dedicated ground too.

You always need a ground.

Right, the neutral is bonded to ground in both panels. What's the purpose of dedicated ground then?

If I'm not mistaken, it is against code to use the neutral between two panels, ground only. The reason is allowing multiple paths to ground.

I cant remember why that makes sense and I could be wrong. I gave myself a crash course on NEC when I ran new power to my garage.


I got that wrong a bit, this is better.
Found this: https://diy.stackexchange.com/questi...us-bar-in-main

I'm still confused. Both houses have grounds, so all circuits will have proper ground wiring.

The old house essentially becomes a subpanel of the new house at that point. So do sub panels need hot/neutral, AND ground connecting them? If so, why?

What is the purpose of removing the bonding in the sub, but not in the main panel?

Visuals probably helps explain these questions.

You're not supposed to, I know you're not supposed to, and i know there's a reason you're not supposed to. That's about the extent of my electrical knowledge.

Hehe, looks like I might be able to tell you first hand why you're not supposed to very soon. 120v is pretty tame.

I interpreted that as for test purposes to identify the two lines.

2x on circuit diagrams help. Earth is ground but there are telluric currents flowing there. I don't know the scale but dirt is probably an insulator. Massive grounds to bedrock let you do some weird stuff. Like Tesla's Wydencliffe tower.

https://ecomodder.com/forum/member-f...ctrickery.jpeg

In the video those plasma jets are making a hissing sound.

With a sub panel you have to run a neutral and a ground if you are running 120/240v power on the sub.
If it's a 240v only you don't have to run a neutral.

The reason why the neutral ground bond is broken in the sub panel is so the ground doesn't carry current.
If the neutral and ground are bonded at the sub then the ground acts like a neutral. Then you won't know there is a neutral or broken ground fault until you lose both.

May not happen on connection, but could on first rainfall or really dry day or anything in between. I believe it is because dirt is a semiconductor with abnormal properties. I also know that neutral is not necessarily at ground potential.

120 might be tame enough to kill. Just like chuck yeager and the super cub "the worlds safest airplane, with just enough power to barely kill you"

I defer to oilpan's experience, as I am a signals tech that also kinda does power.

Well, neutral and ground would be at the same potential if they are both bonded in both panels. Heck, they should be at just about the same potential if they are only bonded in 1, as a grounded neutral from one panel wired to the other would also drive it to equal.

I'm still unclear if the "sub" panel at the old house should be unbonded once I wire things up.

Sub panels are never to have the neutral and ground bonded.
The neutral does have some potential difference to ground depending on the load but it should never exceed 10 volts during normal conditions, ideally it's only around 3 volts.
Balanced load will also help reduce the voltage difference to ground on the neutral.