Electric steps only retract with ignition turned on

Should I hook this new wire up off the chassis batteries so it's always live or hook it up to a power source only live when the battery center is turned on?

The plus of coming off the chassis battery is the switch/stairs always work. Coming off the battery center will only work if I have the house batteries turned on. I guess I can just jump out when it's parked and the battery center is turned off.