Quote:
Originally Posted by MGD
Well, having a masters in electronic engineering for the last 42 years, + stands for positive 12VDC and - stands for 0VDC aka Ground.  |
The + and - on the fuse contacts represent the hot side and the cold side of the fuse contacts in the fuse block. If you remove the fuse and then use a voltmeter and measure the voltage from the hot side to vehicle ground, you should get nominal +12v. If you measure the cold side to vehicle ground you get 0 v. If the fuse position is switched to the ignition, you will need to turn on the ignition to get those readings. If the fuse position is not switched, then you should get those readings at all times.
When you are using a fuse tap to add an additional circuit, the bottom fuse location in the fuse tap is for the original circuit. The top fuse is for your additional circuit. In this situation, it is important to orient the fuse tap correctly ... otherwise, your additional circuit will not be fuse-protected. Your original circuit will not be affected, but the add-on circuit will be.
The term, polarity, may be somewhat confusing, but this is what is meant with respect to using a fuse tap. The fuse itself does not have polarity. Only the contacts in the fuse box.