main power switch for monitors

Right. Sorry about the ground part of the schematic, it doesnt have to be 85 but all ground wires for the monitors will be grounded. I didnt draw in a ground wire next to the positive wire but i'm going to wire it so the positive and negative are together. So I'll ground the monitors to the main ground wire and put the main ground wire onto a ground point on the vehicle. so basically I can wire up everything with a 30A fuse at the battery and the 1A fuse for each of the monitors. i think you said something about a fuse at the relay but i dont understand that one. I just want to be sure that the monitors are totally separate from the factory wiring. I think that's the reason why I read alot of reviews as to why people's headrest monitors just die out within a couple of weeks or months. I figured if the monitors are on their own fused harness then they would work great.

You sorry? No - me sorry! Sorry for the caveats etc. I did mean that your GNDs & #85s were totally ok - "we" know what you meant & drew. I was ensuring that you too knew what we knew whilst informing other that didn't. That's clearer isn't it? (LOL) In summary - you do not need me - you "have it". Yes - a 30A "battery" fuse is fine. [ Not meaning to confuse, but no bigger than 30A, but could be smaller - say down to 10A. ] Yes - "final leg" or tail fusing for each monitor is "ideal". Probably a 1A fuse for each. [Might not be needed though - depends on tail cable etc.] Yes - monitors totally separate from the factory wiring. If only others did the same! I hope if others spot problems that they too reply. Same if they can clarify, or suggest a good practical implementation. IMO - Well done! Trivial additional comments not intended to confuse nor require changes to your system.... IMO - you have a great or perfect design. [At least on paper. Some things override "theoretical" designs. EG - see big 3 upgrade on integra, fuse box where some argue that the 200A alternator to battery fuse (as pictured) is itself a hazard and should be omitted if the issues cannot be solved. That is an example of what I am trying to convey with your "final leg/monitor" fuses. Isn't it ironic if the Intergra alternator-battery fuse - which is intended to "protect" the system - actually CAUSES a fault and burns the car to the ground? Many or older vehicles do NOT have alternator-battery fuses anyway, so why add one? (That is an interesting question with rare answers. I have discussed the issue elsewhere, but in summary, I find that most alternator-battery fuses are a problem, and are probably more hazardous than no fuse.) But the point in the that Integra instance is that adding THAT fuse is a hazard - or at least that is what some argue.... All too often I find the blind application of ROTs like "fuse within 12" of the battery" from the12volt, or "within 18"" or "6"" etc from elsewhere. All to often I have seen destruction & loss caused by the safety devices intended to save us. I do not mean win-lose ratios like seat belts or AC earthing/grounding.    I mean the IMO "clearly avoidable" examples like that Integra example, not having car isolation switches on the hot +12V side of the battery, not having a single RCD serving lights and power to a house, not relying solely on "floating" systems for safety (like batteries for UPS, or mobile RCD protection). Instead I often hear the post-tragic "but who would have guessed?". And increasingly so. ]

Man oldspark, you're one of the best at this. All what you wrote on this thread is pinned onto my corkboard in the office for reference. I'm just glad I was good to go on a theoretical sense and you came through and co-signed on it with extra info for me to know about. I am just waiting on the other two monitors to come in and I'll begin. I'll post pics and everything as I'm doing it. oldspark, thanks for all your help and information buddy.

Wow! Thanks! If only my expression and planning were better. I always intend to but never quite.... (make those Executive Style "master" references.) I've just answered similarly elsewhere (offline) for battery isolation. I suspect the reader(s) will soon also see all the crap that I see published and re-stated. I even mentioned the recent "1AH per 10W" rule - aka "100AH per 1000W". (LOL! As opposed to "100A per 1000W"!). I suspect too that they will also be isolating batteries since the mere $5 additional cost is well worth overcoming the know risks and issues and the restrictions that many claim, and more than worth even bothering to question whether those that say there are no issues are right or not - or the cost penalty with that POV. Funny how saving mere $hundreds for people can be more beneficial than saving $millions elsewhere (even $5Bn per year in one case ha ha!) But I did what I think was a reasonable "covering all overview" yesterday (with only the odd extra "real ramble"). Almost fit for Master Referencing. ( what is the difference, relay, isolator refers.) Thanks again. Let's hope we are both "not wrong".

EPIC WIN!!! THEY ALL WORK!! Thanks for your help oldspark. What is crazy is that I did this project with heated seats since the monitors were on backorder for some time. The heated seat kits came in, made the wiring, laid the wiring out, installed the master switch on the dash and tested the kits before I installed them in all 4 seats...BOOM they all worked! The three monitors came in this past Friday, made and laid the wiring again, tested the monitors out...BOOM they all worked! I dont even know what to do with myself. Thanks for your help in everything oldspark. Love this friggin website!

Phew! Relief! I could reply FIGJAM, but one can never be sure... (I'll FIGJAM that other thread re batteries & "100AH" per 1kW etc. His "battery month" is now up.) Thanks for your update - hence closing this sanity. But most of all, I am so glad it worked, and seemingly so well. (Now, what's the catch???)     Best wishes, Peter.