Battery disconnect wiring
On the house batteries, do you break the positive or negative on the disconnect. Am seeing it done both ways?
Forum Discussion
skipro3 wrote:
It is common practice that when you disconnect a battery for any reason, you disconnect the negative lead first, then the positive. Your situation shouldn't be any different. Disconnect the negative first, even if you are not going to disconnect the positive.
The reason negative is disconnected is because the electricity flows from negative to positive.
The main reason the negative is disconnected first on a vehicle is that a short from the tool being used to remove the terminal to ground would not cause problems for the negative terminal, but could be quite dangerous with the positive terminal: wrenches getting welded in place, batteries exploding, those sorts of difficulties. Once the negative is disconnected, shorting accidentally from positive to ground does not cause fireworks. For an (enclosed) disconnect switch, this is not a concern as one isn't mucking about with metal tools on the connectors to turn things on or off.
On an old vehicle with a positive ground system, the positive pole would be disconnected first.
What direction electricity flows in depends on what the charge carriers are. In metals, they're practically all electrons and so flow from negative to positive. In some areas of semiconductors or in some conductive solutions (i.e. some electrolytes), the majority of charge carriers are positive and so they flow from positive to negative. In some cases there may be both positive and negative charge carriers.
