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I am going to be changing a few bulbs on my Opel Astra's instrument cluster. Part of the process involves disconnecting the entire cluster from the wiring harness and obviously replacing it when done. The cluster contains an Odometer and clock. Would I need to disconnect the battery first, or would turning the car off and removing the key from the ignition be sufficient?

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up vote 5 down vote accepted

When working on electronics, you are best served by disconnecting the battery. The normal sense of your safety (arcing between hot to ground causing burns) is probably not an issue with this. The main issue is protecting the electronics. Even small discharges of electricity (static or from battery) can fry circuit boards or permanently damage the components. Disconnecting the battery helps to keep these very sensitive items from getting harmed. The simple act of disconnecting the power and/or ground from these instruments can cause the small discharge of electricity which I'm talking about. Note I am saying can ... this doesn't mean you will have this type of discharge. Your equipment would probably be safe 99 times out of a hundred ... but that one time you don't ...

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I work in IT, so I've had enough "that ONE time" moments. – Juann Strauss May 27 '14 at 15:52
You and me both, @JuannStrauss! – Pᴀᴜʟsᴛᴇʀ2 May 27 '14 at 18:22
Another issue I've been warned about is that, when working in the front seat, you want to be sure that the airbag system is completely unpowered so that there's no chance of it going off literally in your face because of an accidental discharge/short. – Josh Caswell May 27 '14 at 19:09
Especially considering I will have my face flush against the steering wheel for most of the "operation". – Juann Strauss May 28 '14 at 7:59

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