If no cameras are plugged into it, it's not going to be sending power to those ports anyways. In fact, that's part of the 802.3at/af standard that it adheres to.
I've used one of these meters on my NVR to watch power use in real time, so I've witnessed it myself.
I don't think 600 watts is enough for your grid-tie inverter. My refrigerator is rated at 345 watts, but I'm pretty sure it will surge to 3X that when it starts up. I have a Jackery 500 with a pure sine inverter rated at 500/1000 peak. I haven't tested it with the fridge yet. I'm waiting for a Kill-a-Watt meter to arrive from Amazon so I can check the fridge for peak start-up wattage.
Get a 12 AWG cable. That said, whatever amperage your entire system total adds up to is very likely not what you're going to draw during a show. Get a cheap meter like this one:
https://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU
Plug it into the electrical source. Plug your cable into the meter and run your system at show volume. The actual amps you draw is probably going to be much, much less than the max in your components specs.
Maybe I'm wrong
You are wrong. Buy a Kill A Watt; plug you coffee maker through it and watch it when it brews, when it heats up water, and when it is idle. Also - leave it plugged in for days on and it will show the added-up usage. Your coffer maker is not a huge energy drain. It is when it's heating up water but it's not when it's idle for hours and hours. In general... remember this about electricity: it is very expensive to heat up sh*t(Electric heater) and to cool down sh*t(AC). The other stuff around the house is pretty much negligible.
https://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU
P3 P4400 Kill A Watt Electricity Usage Monitor https://www.amazon.com/dp/B00009MDBU/ref=cm_sw_r_cp_api_i_JBh.Eb7MAAXBB
Shit, this looks like the make/model that I just bought:
Can you confirm that this is what you bought so I can replace it immediately?
What do you recommend on electric measuring tools?
I suggest you start with a killawatt (US example shown - get one to suit your local AC plugs and sockets if different) or equivalent. That will let you safely measure your AC supply voltage and frequency and the current and power consumption of your appliances just by plugging them in to the power meter. You'll get some practical measurements to compare against the explanation of these quantities you can find in online videos or written articles.
Get one of these...
https://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU?th=1
The most reliable way to diagnose this type of problem would be by measuring the actual current that flows through your treadmill. That's likely what an electrician would end up doing once all the normal trouble-shooting doesn't lead anywhere. It should never sustain more than 15A, although a brief spike would likely be fine.
You can pay a couple of hours worth of time for an electrician, or you can buy a digital clamp meter. I linked to the cheapest model that I could find; it's only about $20. I am not saying this is high-quality device, but the price is right.
Clamp meters are highly accurate and would tell you exactly how much current flows through your tread mill. All you have to do is set it to measuring amps and then close the clamp around one of the wires going to your treadmill. You can either do this by splitting a two-conductor extension cord, or you buy a relatively inexpensive line splitter for $16. Amazon has cheaper models, but they looked a little unsafe, so maybe go for the good brand name.
Alternatively, a Kill-A-Watt works similarly, but lacks some of the more useful diagnostic features that you get with a clamp meter. It really depends on whether you think this is a one-off or whether you expect to have other electrical issues that you think you'll need to track every so often.
Triangle is indeed positive, it shouldn't matter much because a switch doesn't get affected by the direction of current.
That said, I would start by checking if all the cables, graphics card, and ram are plugged in all the way. According to your motherboard manual, the motherboard has "EZ Debug LEDs" (pg 40 in the manual) if one of those leds light up that's the problem. If none of those light up, I would check that the powersupply is working either by using a spare powersupply to test and see if your build turns on or by using a monitoring plug like the Killawatt to see if the powersupply is drawing power from the wall. If none of that works, I would remove the graphics card and use the integrated graphics to see if its a dead card. If you have some spare sticks of ram I would try them to check for dead ram, also try the ram in the other two slots.
If it's none of that, I would assume its a dead motherboard or a dead CPU. However, your description sounds like a dead powersupply, so test that first.
I'd do a proper break-in, which is hard to do in an emergency. I've had two new generators. Using dino oil, I start with 15 minute no-load warmup, then change load every 15 minutes for the first hour, not to exceed about 70% of running watts. Change the oil (still dino) and run them for four more hours, varying loads every hour, then change to synthetic oil for storage and the long haul. I use Napa full synthetic (by Valvoline). I use a Kill-a-Watt to test hertz and voltage. Check voltage on both sides. With any air cooled engine, load should be removed and the engine let run two minutes to cool it down before shutdown.
All that doesn't need to be done in one stretch. I took a few days with each new toy, as I wanted to break them in carefully.
Get a Kill-A-Watt meter and measure your amps on each channel. Keep them as much under 2 Amps as possible.
https://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU/
Software isn't very good for this as your PC might not know how much power it's using, it'll just be a vague guess if it's reported at all. I would suggest using a kill a watt instead if it's important information for you.
Kill A Watt comes to mind.
I also bought some Semi Edge nail clippers on Amazon 12 years ago that I still use.
I also bought this Shinwa metal ruler at one point and pretty sure it's BIFL.