Thanks for everyone's replies. As Alan mentioned above, PG&E wants $1,500 to estimate the job. If I decide not to use them, I lose the $1,500. They said it could range between $7,500 to $20K! It all depends on how far they need to trench.
All poco's (slang for power company) charge for engineering. FWIW 20k in CA is pretty cheap if you consider wages, retirement, overhead expenses etc. It's brutal but reality.
The funny thing (not really) is they couldn't find the PG&E vault box that feeds my house. Their map says it's across the street but they couldn't visually verify it so they couldn't 100% tell me if the wires were direct buried or whether a conduit was used. Based on their inspection of my neighbors vault box and given the homes were built in the 70's they said the powerlines look to be direct buried. I'm not exactly sure that's true since a different electrician thought he saw a 1 1/2" to 2" conduit leading into my electrical panel. Could a powerline go from being direct buried in the street into a conduit at the homeowners property or does a direct buried powerline stay direct buried through the homeowners property up through the electrical panel? In any case PG&E said it needs to be 3" anyways so trenching would be required.
This also extremely common, if they even have any "as builts" on hand its unlikely they are accurate. During 70's 80's "beautification" acts were common. Pg&e does not follow NEC (national electrical code) they have their own code commonly called the "greenbook" (you can find one online pdf. The codes are drastically different. Direct burial was common, usually aluminum. Eventually the wire will fail no matter what. The earth will reclaim this material. Also common is a stub of conduit going up to the panel (slang is a sleeve) new service wire NOW has to be conduit (creating shedule)
I called 811 in hopes they would identify the powerlines leading up to the vault box but they said they'll only check the area you have marked off for digging. The problem is that I don't know where the existing lines are for my neighbors (neighbors don't know either). It's difficult to get bids from contractors if they don't know how much they need to trench and PG&E wants $1,500 to start the process.
Again common (sorry) you could go out with ground paint yourself and mark suspected areas for 811 (aka underground service alert USA) they need parameters to operate their equipment.
The whole purpose of wanting to upgrade my electrical panel is because I'm looking to build a detached ADU (Accessory Dwelling Unit) and all the contractors are telling me I need to upgrade my electrical panel (even though the county told me there wasn't a requirement to upgrade, only that it needed to be connected to the main house). I understand upgrading the electrical panel will help with the additional loads the ADU will require. Given the cost of trenching, I was hoping an alternative solution to upgrading my electrical panels was to power the ADU off solar panels and battery backups (even though ADU will still be connected to main house).
Tesla 4kw solar system and 3 Powerwalls are going to cost $24K after tax incentives. Not cheap but I would rather invest the money into a solar array system vs. paying the same amount for trenching. Do you think this is a viable solution? I'm not an electrician so I'm not sure if this setup would work if ADU is connected to main house. I know typically battery backup is used when the grid goes out but not sure if I'm able to pull from battery to avoid tripping any circuit breakers in the main house. ADU would have it's own breaker but I don't know what happens if ADU and main house pulls too much juice at the same time (which circuit breaker trips?). It's the circuit breaker tied to the appliance that pushed loads over 100A right?
Grid tied solar has no bearing on this. When the grid goes down so does pv generation. Batteries are backup only. Nothing supplements load calls. Load calls are not rims, it's more complicated than that. Nec codes for distribution from panel out don't consider efficiencies of consumer products
I guess there's no way to know for sure unless I pay PG&E $1,500 ugh! If it turns out it's $10K, maybe it makes sense to trench but I'm still needing to power the ADU which requires solar panels to be installed anyways.
No it doesn't, engineering of load/distribution etc. Is its entity. Grid tied renewables are supplemental. FWIW pg&e doesn't want homeowners to generate their own power. They would prefer solar microgrids that they would control. In fact the lobbying to eliminate personal renewables is heavy.
I understand this is frustrating but things aren't as clad in stone as most think. The macro picture in California is very complicated. On the execution end of work alot of info is tribal and fluent, very fluent
