territorialmillworks Posted February 18, 2012 Share Posted February 18, 2012 I have a 5HP, 220V, 20 amp compressor that gets low to moderate use. Run length to panel box is 10 feet so there isn't any line loss. Problem is that the contacts will fuse together and I have to repair/replace the pressure switch about once a year and of course this "only" happens when I'm in the middle of something. Like this morning,, LOL. I usually buy another switch on ebay or pay double at the local repair shop. So my questions is this, if I spent 3 or 4 times the $ and bought a magnetic starter/pressure switch, would I get better service and eliminate the fused contacts? Thanks for advice---going to pry the contacts apart and file them smooth Quote Link to comment Share on other sites More sharing options...
macbruce Posted February 18, 2012 Share Posted February 18, 2012 Running a 5hp without a starter is not recomended, the spike in voltage is huge across metal to metal contacts......The next thing that fries will likely be the motor and that makes the starter cheap by comparason.......Any motor above 3hp should have a starter...IMO. Quote Link to comment Share on other sites More sharing options...
fciron Posted February 18, 2012 Share Posted February 18, 2012 I'm with Bruce on this one. That pressure switch should be controlling the magnetic starter, there is no way it's rated for a 5 horse motor. I've been running the 5 hp motor on my compressor with a magnetic starter for 12 years and have never had to fix anything. When I'm using the bead blaster it's switching on and off every 15 minutes all day long. If I'd been fusing the switch once a year for twelve years I'd have payed three or four times the cost of the starter by now. Buy the starter, it's a lot cheaper than a fire and a lot cheaper than repeated down time. Quote Link to comment Share on other sites More sharing options...
Kevin W Posted February 18, 2012 Share Posted February 18, 2012 I've had a similar problem with my comp, same set up. 5hp ... About 6 ft from the box fused contact. Mine is kinda cobbled together and there are no replacement parts. Inside of mine, that springy piece of metal that made the contact had a soldered on rivit, that rivit had worn away, so the solder was melting when the compressor kicked on. The first few times I just cleaned it , finally I I drilled out that old rivit and made a pretty heavy copper one, rivited it on - no solder, no problem. That fix has worked for ~2 yrs. I,m curious what others think about swapping to the magnetic switch too. As I recall the replacement for mine cost more than I have in the compressor all together. Quote Link to comment Share on other sites More sharing options...
macbruce Posted February 18, 2012 Share Posted February 18, 2012 I,m curious what others think about swapping to the magnetic switch too. As I recall the replacement for mine cost more than I have in the compressor all together. You must have got a smokin' deal on your compressor............ New Magnetic Motor Starter Control 5hp single phase Returns: Accepted within 14 days Quote Link to comment Share on other sites More sharing options...
Kevin W Posted February 18, 2012 Share Posted February 18, 2012 My recall has never been what it used to be. What I had priced was the pressure switch regulator w/gauges part. This Magnetic motor starter goes inbetween the pressure switch and the motor? Is this a redundant part it the electric motor has a reset button? Yes a smokin deal, it just cost me time, the speedaire tank and compressor were left for the garbage to pick up and the ge motor was given to me. Quote Link to comment Share on other sites More sharing options...
macbruce Posted February 18, 2012 Share Posted February 18, 2012 The pressure switch comands the starter, then the starter starts the motor..... :) Quote Link to comment Share on other sites More sharing options...
mike-hr Posted February 19, 2012 Share Posted February 19, 2012 Don't know if this is on topic or not.. Last summer I aquired a 3ph 240v 2hp compressor. I called my sparky friend, Crazy Dave, and told him to put an appropriate starter, on/off switch to it. He had a used magic box he turned me on to. Anyway, it has a little set screw that sets the internal breaker to trip at anything more than normal in-use power. He said that if it starts to trip all the time, check for bad bearings or low oil level, etc. It's supposed to alert me to maintainence issues before the whole motor or pump burns out or frys..Seems like a good idea, I love this compressor, anything to keep it working hard and happy is a good thing. Quote Link to comment Share on other sites More sharing options...
territorialmillworks Posted February 19, 2012 Author Share Posted February 19, 2012 Thanks for the link Macbruce...order it this morning...I'd been pricing mag starter/pressure switch combos and didn't want to spring for the money. Then figured out that I could use the current pressure switch to control the contactor. Mama always said i was the slow one of the family......Keith Quote Link to comment Share on other sites More sharing options...
fciron Posted February 20, 2012 Share Posted February 20, 2012 I'm glad Bruce straightened that out. I got carried away with clever math in my first post and didn't make it clear that the pressure switch should only be carrying a tiny fraction of the current. I need to work on explaining myself better. Lewis Quote Link to comment Share on other sites More sharing options...
macbruce Posted February 20, 2012 Share Posted February 20, 2012 Are you thinking of wiring it yourself? Quote Link to comment Share on other sites More sharing options...
BLAM! Posted August 11, 2014 Share Posted August 11, 2014 Thanks! Just found this- exactly what I was looking for for my "New" Murray hammer! Now I just have to see if I can use the old push-button switch from the original 3 phase set-up. New Magnetic Motor Starter Control 5hp single phase Returns: Accepted within 14 days Quote Link to comment Share on other sites More sharing options...
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