Can I find a good 12v switched source for my gauges under the hood. I would use the ignition spade at the fuse panel, but I've already tapped a couple of wires off of it.

 

Go to mad enterprises and order an insulated terminal block. I use a few of these.

 

What gages do you want to add? Voltmeter, temp and oil pressure? See if there's an unused ACC tap in your fuse block. You'll still have switched 12v, just in ACC as well as RUN.

How many amps does the other equipment on the IGN plug draw? I'm thinking add an inline fuse holder with, say, 15-25 amp fuse, and plugging that into the IGN plug cavity. Then connect your individual loads to that with insulated terminals. You gain fused protection as well as extra switched 12v sources.

 

I've got Pertronix and my aftermarket stereo tapped into the ignition terminal. I'm sure together they draw alot of amps

 

I need to run power to my water temp and voltmeter gauges

 

I do not have a spare tap in my fuse block

 

Go to a wrecking yard and get the power terminal block off the firewall of any 1973-91 Squarebody full size pickup. Run a wire from the fuse panel tap to this, then add whatever you need.

 

What car are we talking about? You need a factory shop manual with the color wiring and fuse block diagrams to see exactly what fuses and taps are constant 12v, switched ignition and switched accessory.

 

Elegant. Just pure elegant, as Joe P's solutions always are! Had forgot box trucks had those.

 

Appreciate the advice Joe. That looks like the way to do it.

 

Is all of this really necessary? The voltmeter draws ZERO power. It measures voltage at infinite resistance. No current draw at all. The only power it might need is for the little bulb that lights it up. Just stick the wire coming from it into one side of the fuse tap for the radio. That's what I did. You don't want the voltmeter showing the voltage all the time, which it would do if you powered it from, say, the clock fuse. You just want it to show the voltage when the ignition is on. The radio tap will do that. That's how I hooked up mine. Works fine, and you don't have to run any wires through the firewall.

As far as the temp gauge, that does draw a small amount of current, but it's negligible. I have one in my car, and I power that through the radio fuse as well. Again, it has a little light that illuminates the gauge at night, and, again, the power draw for that is not worth mentioning. For the dial illumination on these gauges, just tap into the wire for one of the dash lamps.

I could see putting a truck terminal on the firewall if you're installing subwoofers or police sirens and lights, but not for this kind of stuff. It gives new meaning to the term "overkill."

 

That can be a good solution; however, not everyone shows logical restraint in adding loads to our old cars with their old wires and old connections. The ancient fuse panel wiring can heat up and melt down when more load is added to it.

If you need a terminal block to connect more equipment that needs power from ACC or IGN, it's safest to add that power through a relay.

Source the relay operating coil (marked 85) from the appropriate fuse-block terminal--ACC or IGN. Ground the relay operating coil (marked 86).

Feed the relay power (marked 30) from the battery using a fusible link at the battery.

Feed the under-hood terminal block from terminal 85 on the relay.

Use fuses on connections from the terminal block as Joe's photo shows.

 

Those are great for your power source but if you need the power to be switched, add a relay. These come with a fuse slot incorporated into the relay housing. Run the power source lead to the fuse link that Joe shows, and power the switching lead off the fuse block, add the appropriate size fuse for the device being powered. That way you have minimal power going through the fuse block but still switching any device you want or need. Available from ebay here
Fused Relays

 

I agree, the other suggestions are a bit of an over kill for some gauges.

 

He about put a contract on my head last month when I suggested a mechanical gauge, so who knows?

 

Maybe someday Joe and I will stop thinking in NASA and nuclear terms and cjsdad will stop thinking in high end stereo install terms...

Until such time as that happens (if ever), IT'S WHAT WE DO!🙃

 

Personally I would have used solder and shrink tubing and this problem would have been solved about a week ago. We've spent waaaaay more time talking about it than it takes to do it.

 

Appreciate your input cjsdad. Maybe it is overkill for wiring my gauges, but I can see these as a good way to power many different components. I didn't understand vc455 when he mentioned all the different numbers until I checked out the link for the relay.