I want to add a fuse block to run my lights and 2 accessory 12v usb plugs. I don't want to go direct from the battery. I have a 4 bay 32v 100 amp block that I want to use. Can I splice into the power wire from the main fuse block to do this? Attached is the block I have. I'll be running a 144 watt light up front and a 60 watt out back.

[2015 Z Force 800 53/Trail EPS]

As long as there is a fuse between it and the battery or your draw on that circuit has no effect or lowers the voltage to the fuse box and it's loads/components. That main power supply may not be keyed power so your box may always be hot. Not sure without looking. It is my opinion that if one is going to add extra items that use "significant" power, one should not place that load anywhere on the original system or harness. Really should run a separate fused power supply to a relay triggered by keyed power such as the accessory circuit. Really simple and the safe.