I've been handling stuff attached to low voltage wires for over thirty years. Bear with me youngsters. Years ago a regular client called to say their "system" was not working at all this morning. Her: "We need it desperately. Can you please have someone come over right away?" Me: "yes mam we'll take care of it." I rearranged the schedule of my two best techs and alerted them to the call. They made it their first call of the day and quickly located and solved the problem. The unit was not plugged into the wall. No power. I sent the client an invoice for the minmum service call charge. She client called right away after receiving the invoice. Her: "How can you charge me for a service call when all they did was plug the unit in?"