Run power source for relays.

[Kendog 170]

I'm curious what would be the best area to tap for added relays for various wiring mods. Say like the Blue wire that runs to the ballast? What say you?
Thanks

 

[MadScientistMat]

It depends on what you're powering, but normally you want fused constant power. Also, are you using an ammeter? The alternator power lug is often a good spot - it's getting current directly from the alternator and will not mess up the ammeter if used. It's also well positioned for headlights and fans.

 

[Kendog 170]

I have a Denso Alt. power wire to the Battery in trunk. I see some use a relay to shut down the power to Battery when the car is off. I do have lights and fan (fused) running off a Power junction run off my starter relay. Old Pic. No MSD anymore and other changes. I have a 4 gauge wire from trunck to relay not shown in this old setup.

 

[jbc426]

I'm curious what would be the best area to tap for added relays for various wiring mods. Say like the Blue wire that runs to the ballast? What say you?
Thanks

I generally use non-switched 12V like you have shown in your photo for the main relay power, and switched 12V for the relay trigger wire.

You can use that single attachment point distribution lug to add individual fused outputs. I always use a Marine Grade products for wiring accessories.

 

[Kendog 170]

Which wire switched 12V for the relay trigger wire the blue wire to Ballast or at the fuse box?

 

[jos51700]

If I'm running more than one relay/circuit, I use one relay to control power to however many relays I'm adding, and use a single key-on power source for that one primary relay (this is similar to the auto-shutdown relay in late model cars). At this point, i just run the power source for the extra circuits right off the battery.

It's none too difficult to rob a fuseblock from a late-model that will include the ASD relay system and usually a nifty cover with labels...depending on what you're adding.

 

[DionR]

Just remember that the blue wire goes dead during starting. Might not matter, but something to keep in mind if you are powering things that are needed during start up.

 

[Kendog 170]

Just remember that the blue wire goes dead during starting.

Thanks. That basically answers my question for the Blue wire. Now to locate the key on power source wire to tap into.
Electrical isn't my strong suit. Trying to avoid mistakes which I already have done and corrected in the past.

 

[jos51700]

Thanks. That basically answers my question for the Blue wire. Now to locate the key on power source wire to tap into.
Electrical isn't my strong suit. Trying to avoid mistakes which I already have done and corrected in the past.

I don't know the specifics of your car, but on the back of my [factory] fuse block (the top of it as it's installed), there were some power tap spades. I just used a multimeter to see what's key-on, and then picked based on what would cause the least issue if I were to pop a fuse. It's ONLY powering the relay if you do it properly, so the additional load on ANY circuit should be minimal. That's the beauty of relays!!

ETA Photo of '66-'69 block

 

[Kendog 170]

Thanks. Now both my questions are answered.
Thanks everyone.