Pulling a 400 HP, DC motor out of a lift today. Going into the motor shop for new bearings and cleaning. We do this every 5 years to prevent break downs. This motor weighs 4500 Lbs.
I had a close call yesterday, a wake up call for sure! I was troubleshooting a 490 volt control system, feeding an oil pan heater for a auxiliary drive engine on a ski lift at Purgatory. The thing was, the guy that wired it made a crucial mistake! He brought the hot 480 volt power leads in on the bottom and connected them to the bottom of the contactor! Major no no! You always bring the hot feeder lines to the top and connect them to the top of the contactor, it's the industry standard!! It's what we all expect. It's what we take for granted, that the top is HOT! Not the bottom.
I made a mistake too...I broke the cardinal rule! 'Identify the source, then verify it dead' with your meter! I didn't do that. I had my meter out, and I checked things, but didn't verify the incoming hot leads! I thought the 'TOP' of the contactor was wired to the hot leads.....it wasn't!
So, now I've got 500 volts AC, coming into the bottom...and I thought the power was off in the panel! Well, it turns out, I had a guardian angel that day, watching over me. I reached in and touched a screw that I was unhooking, and felt a little tingle in my hand...hmmm, was that a shock, I wondered? I grabbed my meter and started testing everything for power. To my horror, I realized there was 500 volts coming into the bottom of the contactor, HOT!
The reason I only felt a tingle is the lucky part....
The line I touched had live power on it, but it was feeding through the bad heating element (the reason I was there) first, then to me! This reduced the power I got substantially. I hardly felt it! Had I touched any other wire, I would have gotten nailed!
It was a bad mistake, one I won't make again! I have been reawakened! Lucky day for me!! Thank you, angels....Craig
Working on a low pressure protection circuit on a pump this afternoon, then this great light rain started, and a beautiful double rainbow popped out!
I wired in this pump control to the existing Munro pump control panel. System is controlled with a Hand/Off/Auto switch. In 'Auto', a Rain Bird irrigation controller signals the relay in the lower left of panel to start a pump, and stop it after zones cycle. Customer was having to turn it off and on manually, and asked me if I could do this. They were very pleased to have it!