Grounding issue?

If you didn't have the problem before switching the bridge, I would bet you need to revisit the installation and be sure the ground wire is making contact. BTW if the wire is not connected properly you could be in for the shock of your life.

 

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It's happened to me when using a microphone when my bass was ungrounded. Nice little shock and it left a mark on my lips. Might have been a combination of the two, but it was enough of a jolt to wake my ass up.

 

The bridge ground completes the grounding of all metal parts. When its not connected you can be severly shocked if there is a grounding problem with your amp.

 

Actually it's the other way around. If the bass parts aren't grounded, there's no place for current to flow. No shock.

 

So you are recommending to disconnect the bridge ground from all basses?

 

It's the safest solution, but obviously less than wonderful.
Here's some good info on the subject:
http://www.guitarnuts.com/technical/electrical/safety/index.php

 

I defer to the electrician. Of course I've been playing on a wireless for many years and haven't been shocked since becoming untethered. I also carry a circuit tester to check wiring at my gigs. Its amazing how many places I've played with wiring problems.

So the OP either has to live with the hum or face a better chance of being shocked. Neither choice sounds desirable. I just know that years ago I was instructed to NEVER disconnect the bridge wire. Live and learn.

 

I think if you read that link carefully, the electrician is not saying that disconnecting the bridge ground is the safest thing to do, because that could leave other parts of the bass connected to the dangerous voltage (like knobs and pickup covers).

Without going back and reading it again, what I recall he said was the safest thing to do was to only use equipment that is properly grounded, and only plug it into grounded outlets that you've tested to be sure they are wired correctly. And make sure everyone else on stage does the same thing.

Coming back to the OP's original question about hum after installing a new bridge, I have to ask: did you remove any paint or oxidation on the bottom of the new bridge in the area where the ground wire makes contact? The wire should be in contact with shiny metal. If the bridge is aluminum, it is probably oxidized from contact with air (think about the white oxidation that forms on aluminum screen doors). It might even be anodized, which is a form of chemically applied oxidation. Aluminum oxide is an excellent insulator.

Ed