To my understanding, the reasoning for "remove the negative cable first" is that if the positive terminal is exposed and you somehow make contact between the positive terminal and any metal in the body, you risk a short. Is that the only reason it's suggested to remove the negative cable? I imagine if necessary it could be mitigated through being very careful and/or covering the positive terminal with something nonconductive after removing the positive cable

The reason I ask is the position of the battery in my vehicle. I'm looking at adding a subwoofer which I understand well enough. I'll need to remove the battery to get to the hole in the firewall to run the power wire. Looking under the hood, the positive terminal on the battery is exposed, while the negative terminal is underneath the wiper cowl -- maybe someone with less chunky forearms than me could get to the negative terminal to remove it first, but I can't. I think I'm going to have to take off the positive cable first, but before I do I'm trying to understand why I always hear to remove the negative cable first.

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  • 2
    Saw a friend who had a metal watch strap regret not removing the neg terminal. Imagine a red hot band of steel clamped about your wrist - hurts like duck…
    – Solar Mike
    Sep 1, 2021 at 21:11
  • @SolarMike a frend if mine did this too,it was welded shut and did glow in a whieish color. Sep 2, 2021 at 4:48
  • The duplicate answer in the link isn’t totally correct. It is as @SolarMike said that there is less risk of shorting the battery if you disconnect the negative first. If all you can reach is the positive terminal, then just be more careful.
    – HandyHowie
    Sep 2, 2021 at 5:54
  • @HandyHowie If "all you can reach is the positive terminal" you are doing the job wrong. Period. No exceptions (unless you are working on a 100-year old vintage car, perhaps).
    – alephzero
    Sep 2, 2021 at 14:40
  • 2
    There are easily imagined situations where it might be harder to remove the negative terminal. Not all repairs are done in professional shops with a full set of tools.
    – barbecue
    Sep 4, 2021 at 0:35


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