I'm almost embarrassed to ask this; but my electrical knowledge is a bit rusty. I have googled a simple query "Can a single wire from a power source power 2 relays?".
Or "can one powered relay be jumped to power another relay?)
Either my terminology is confusing or I'm just not understanding the answers

The image below simply illustrates one version of my question:


A simple mock-up: A 30amp fuse from battery to power 2wo separate relays.

The reason that I ask, is that, I have several switched accessories I'd like to power independently/each connected to their own relays.
I'm trying to avoid running too many wires (from the battery) through the most accessible grommet in the firewall of my R53.
I prefer not to start drilling holes as to be able to revert back to stock/factory condition (someday).

Does this make sense/can it be ok?.... Or just another bad idea?

Thanks.

 

Should be ok if the proper gauge wires are used for each terminal. Edit: The red wire above doesn’t look like it’s the right gauge for a 30 amp load. I would increase the wire size or use a smaller fuse.

I’ve run one +12v power line for a few relays, and also used small jumpers from the same line to power the relay coils, but the relays were for lower power accessories, mostly to control aftermarket door lock motors.

What are you planning to power with the relays?

 

Just because the relay is rated for 30amp doesn’t mean the load and wiring have to be rated for 30amp…. Make sure the wires and fuses match the load, and you should be fine. Maybe instead of one fuse for all loads, place a single fuse for each load / relay. And wherever you combine two power wires, I might suggest a step up in one wire gauge - ie 2 14ga wires connected with 1 12ga wire.

 

The photo is just a mock-up.
But currently Installed in the car; I have a: 10gauge (or 12), w/15amp inline fuse wired directly from the + side of the battery to a 30amp relay which in turn currently powers my front Rally lights.
I am attempting to power a low 3amp micro switch wich will activate a pair of modded rear LED fog lights I've incorporated into my rear bumper grilles.

​​​​​​Although - now after running the wires and making the connections in the car - The LED's are not illuminating as brightly as when I initally "bench" tested.

 

yes - Tho not shown in the photo- In the car, from the 12 gauge battery wire I also have a separate <5amp> inline fuse connected to the second relay I am utilizing for this purpose. Additionally I have a piggyback 5amp fuse connected to the +side of the 3amp micro switch to power only when the car is running.
maybe confusing.
I'll try to upload a photo if it might help.

 

Is this with the car running, and are the rally lights on at the same time? What was powering the circuit during the bench test? Could the power supply have been supplying more voltage than what the LED’s are getting after once installed in the car? I would also double check the ground for the rear fogs to make sure it isn’t causing a voltage drop.

 

Thanks for your help.
I wasn't able to get any photos of my wiring and relay in the car. I was (overly) confident when installing and everything is tucked in and hidden from sight.
My "bench test" setup was performed using an improvised 110v to 12v transformer. Similar to that for charging/plug in a lap top or powering outdoor 12v landscape lights.

I tested with the car off and then with the engine running. While the engine is running the lights seemed a little brighter. Noticeable but not by much.
The lights are grounded well with 12 gauge wire to the framework to an inside bolt under the steering panel/bolster. I tested the ground with a high intensity 12v LED lamp. It lit up super bright so there is no problem there.
HOWEVER; I'm beginning to suspect maybe the "issue" has something to do with the proper amount of voltage that is being carried through a ridiculous pipeline of varied wire gauge...

Here's a photo of the component's wire sizes that has me wondering:


The components that are being wired...



I had thought about re-soldering/wiring 18gauge wires to replace the 20-gauge wires that are connected to the fogs' LEDs...but that seems like a headache.
Does anyone see an issue with the difference in wire sizes that are being "asked" to carry the load(s)?

EDIT: In the last photo = close up; The wires leading from the fog lights are 22 gauge (or less). Not 20 gauge.
Also - no other lights or accessories were powered on while testing the lights wired up in the car = engine off / or running.

 

@RB-MINI - It was a bad ground.
After jumping the relays I hadn't sufficiently tightened down the ground bolt connecting the relays.
I could have sworn I hadn't missed a thing

Which brings to mind one of my favorite aphorisms which was quoted by Mark Twain - "It's not what you don't know that gets you into trouble. It's what you know for sure that just ain't so".

You, my friend, were right.... Again.
Thank you!

 

Glad it was something simple and you got it working.

That is a great aphorism, and thanks for making me look up the definition of an aphorism.