Electric issue

[Badgerman]

Good morning, why should a mechanical disconnect of the chassis
battery only be put in on the negative side of the battery? Thanks
06 Manaco Camelot.

[Gary RVRoamer]

It's not a major thing, but opening the ground side reduces the chance of a spark if somebody accidentally shorts the hot side of the battery while working on it. If the switch is on the hot side, any contact between the positive post and any ground, anywhere, will still cause a major arc.

[Catch and Release]

Quote:

Originally Posted by Gary RVRoamer It's not a major thing, but opening the ground side reduces the chance of a spark if somebody accidentally shorts the hot side of the battery while working on it. If the switch is on the hot side, any contact between the positive post and any ground, anywhere, will still cause a major arc.

I was thinking about this a few nights ago and have been trying to remember why this is true. I have an electronics background in the military.

A spark is created any time there is a difference of potential across any 2 leads. Why would it make any difference which lead (positive or negative) is used to complete the circuit? If I remember correctly the reason to open the ground side is because it can be the most distant connection from the battery. If removed at the battery, either connection is just as likely to create an explosion because of the gas created by the battery.

Not trying to be a wise a** but thought it might be a good discussion.

[RVDude]

I think the point is, if switch is on + then a wrench dropped/placed ON the + POST (anywhere before the switch) and hits anywhere on chassis it will arc. Whereas, if switch is on - then the ONLY short/arc possibility will be a direct post-to-post connection. In other words, the entire chassis is removed from being a danger area.

It is a seemingly small difference, but can be significant.

[Gary RVRoamer]

As RVDude says, it is because of the chassis ground system. If it were a wired ground system, i.e. everything had both plus and minus wires that run back to the battery itself, it would make no difference at all.

It's a very minor thing, and I've used a disconnect on the positive terminal at times, when other factors made that a better choice.