If you are hooking up IP cameras you probably are connecting them via POE (Power Over Ethernet). Seriously since you have to get power to it you might as run Ethernet cable to it to avoid WiFi issues and power them off the same UPS. Despite the Amazon title for this device it works good with 12 volt systems too. POE or old school analog power cables. Not only will this show that the camera is getting power but also how many amps it is drawing and the actual voltage. Then you can compare the end of the line voltage to the source to see how much loss there is so you can easily see if there is an iffy connection or too much loss due to the length being too long for the cable type you are using. Always try and keep the loss to less than 0.1 volts.
So useful I bought a second as a backup after I forgot to put the first one back in my tool box once.
If your camera does not support POE directly but has the standard 12 volt connector, you can pick up a Huacam HCP05 Passive PoE Injector/Splitter with 5.5 x 2.1 mm Connector to convert it to POE.