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Comment by jessaustin | Hacker News Reader

In a single building DC could work. Thick wires are expensive (and always will be), so in a neighborhood it's probably best to just go ahead and hire an electrician if you need one. EDIT: actually I believe the cutoff at 50V isn't because it's safe to be shocked by current below that, but because phone line voltage is 48V and the NEC doesn't want to step on the phone company's toes.

I've done a fair amount of line-voltage house/business wiring myself, and I've never taken any electrician's tests, but then again this hasn't been in highly unionized/severe inspection locations.

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You can kill yourself with a single 9 volts in theory http://www.darwinawards.com/darwin/darwin1999-50.html

I was told in introduction to electronica that sadly it's terribly easy, and the teacher claims he has seen it happen. If you manage to take a 9 volt battery and scratch yourself with it (very easy with the negative contact, not so easy with the positive one), and both sides contact blood directly, the current may flow through your hart and may stop it (CPR will restart it, but that of course assumes someone's there to do it, and that people realize what's happened in the first place).

I can't believe someone actually stuck essentially needles connected to a power source into his blood. What. The. Fuck.

Yes thick wires are expensive, but there are plenty of places where houses are only 50 feet apart.

That means your round-trip run is only 100 feet so you can look at this chart (http://en.wikipedia.org/wiki/American_wire_gauge#Tables_of_A...) and divide the Ohm/kfoot by 10. If you used 4 gauge that would be 0.24 ohm/kfoot or 24 milliohms per 100 feet. 24 milliohms on 100 amps is 2.4 volts of droop or a 5% loss. Not awesome, but as an engineer, acceptable.

The 4 gauge is available in quantity for less than $1/ft. 1 gauge is available for about $2/ft neither of those prices are all that daunting.

If you lived on the ideal setup where you have neighbors on either side and off the backyard you could wire 6 houses together for less than $1000. Divided 6 ways that's $160 as a one-time cost to be able to be a lot less careful about your power usage. Hell everyone could net-meter with each other and settle up occasionally if someone's consumption got severely out of balance.

The thing that I really like about this (and which perhaps makes me overly optimistic) is that it would spur a lot of neighborhood engagement and re-forming of communities in the suburbs, which is somewhere that's severely lacking in a lot of places. Perhaps that desire is clouding my rationality; I can't say for sure. But I can say that with the population's general mistrust of large institutions growing by the year idea like this are going to look more and more attractive as time goes on.

https://www.google.com/search?q=millennials+distrust+institu...

My impression, from a number of years in suburbia but admittedly still with a limited slice of it, is that a lot of people who like to live in suburban areas find a need to coordinate with neighbors over resources actively distasteful, and would rather buy them in an impersonal sense from a general provider. I.e. it's not just that they prefer the physical form-factor of a house to an apartment, and would otherwise be fine with some of the communal resource-negotiation that goes on in apartment (central heating, common maintenance of the electrical system, etc.). Rather, one of the things they prefer about suburban houses is that there isn't much need to coordinate with your neighbors, over anything more important than maybe trimming your common hedge at the property line.

Correct. It is total power delivered. You can still short 48V wires and start a fire with high enough current.

Yes, most car-battery injuries are burns from inadvertent tool shorts. Always disconnect the negative post first, and connect it last.

EDIT: yes I'm sure. As wtallis suggests, isolation is important. But while the battery is still connected, there is no isolation. In that configuration, if you have a tool on the positive terminal connector and it strikes any other conductive component of the car, that's a short, which could heat the tool and burn you (among other things). If instead you follow my advice and disconnect the negative terminal first, when striking e.g. a fan pulley your tool is simply an additional connection from the frame to ground, which has no effect. (After you've disconnected negative, a connection from positive to the frame is not a short.)

Are you sure that isn't backwards?

I was thinking that too, until I remember that current flows from the negative terminal. Electrons have a negative charge. Because when Ben Franklin was deciding what to call things, and made a guess about which way it flowed, he guessed wrong.

Negative vs. positive doesn't matter. What matters is that you isolate one of the battery terminals before doing further work. If you've got a single wire attached to the negative terminal and several attached to the positive, then the breaking the negative connection gets you the most safety in the least steps. If there's only one wire to each, it doesn't matter.

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