Electrician Question - Connecting detached garage

[redpoint5]

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.

[oil pan 4]

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.

[redpoint5]

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.

[oil pan 4]

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.

[redpoint5]

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?

[Piotrsko]

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.

[redpoint5]

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?

[Piotrsko]

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

[ksa8907]

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

[ksa8907]

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?