[ChuckE]

Now, here's another item that some of you might be confused about. Some of you seem to be concerned about the fuse you are tapping to. Whether it is 5, 10, 20, 40, whatever and you wonder if the existing fuse can handle it. Don't worry about that. The existing fuses in your car are for the existing "old" device and the wire connecting between the fuse and that device. That fuse protects the in-car wiring and the device it is connected to. Your new added fuse will not be using any of that - remember you are adding a fuse, and some new wire, for your new device.

All of the fuses in your car's fuse block have a buss strip, under them, which supplies the 12v to that fuse. The other end of that fuse is then going out to that device. However, the underlying buss strip (which you can't see) is quite sturdy and it can handle LOTS more current than just the current needing to go through that fuse. It is a buss, usually a flat plate that connects to multiple fuses in that fuse block.

When you use an AddAFuse (or other similar plug-in fuse adding device) you just want to be sure that when you insert it so that the added free wire (that "pig tail") is on the NOT-buss side of the fuse. That way the buss side (the one where the actual 12v source is) is going to supply the 12v to the new added fuse. To verify that you can try and touch your voltage checker to the socket when no fuse is in the socket. But, that can be hard, or awkward. To make it easier, all you need to do is plug the AddAFuse plug into the place where you wanted to tap to. Don't have any added fuses in the AddAFuse yet. Then just check the voltage on the new "pig tail". If there is 12v there then you have the AddAFuse in backwards! Turn it around.

The reason you want the AddAFuse in this direction is so that the new AddAFuse will draw its current from the buss, and NOT through the existing fuse (which you will place in the relocated "existing" fuse position).

In reality, your AddAFuse will work in either direction. But why would you want this new circuit to draw through the old fuse?

Once you have the AddAFuse properly oriented, just re-install the "old" existing fuse into one of the two new sockets on the back of the AddAFuse. The "old" fuse location will be the one that does NOT connect to the "pig tail". Your new device gets a new fuse in that other position, of the back of the AddAFuse, and the "pig tail" gets wired to your new device.