Just got a new (old) compressor and have have got everything hooked up but am now find that I am blowing 20a fuses, every time I try to start it (started once). Compressor has 3hp baldor motor rated for 16amps. I am wondering if I just need a larger size circuit (30a?) or do I need a special starter? The motor has a large box on top of it – is that a starter? I verified the wiring diagrams are good. I was testing on my existing 20a line for the TS and planer (230v). Works fine for those 3hp motors. Also, the compressor worked fine at the place I bought it, but don’t know the line size. Any ideas? I should note that I don’t have a shutoff box yet so I am just plugging into the wall to start. Will fix that once I determine the wiring requirements. Should I try 30a fuses in the 12g lines, as I think it is just spiking on startup?
Nathan
Edited 4/1/2008 10:40 am ET by Nathan Barnard
Replies
20A is not enough to start that motor as it will always start under load.
Harry
I think you need time-delay 20A fuses.
-Steve
Different fuses are definitely in order. Ask for a fuse rated for "motor start", they have a short time delay for overloads built in.
20A slow blow fuses will probably solve the problem. If they don't, it would be dangerous and a violation of the electrical codes to go to a 30 amp fuse for 12 ga wiring.
John White
Well, I have finally got it to work. 20a-time delays and 30a regular fuses wouldn't start it. 30a-time delays seem to be the trick. I've had it started several times without issue. I'd like to borrow an amp-meter to check the running amps when hooked up to the compressor. I'll definitely run 10g wire with a disconnect box now that I know what it needs to run. For a motor that's rated 16a, I am hoping it is correctly sized for the compressor. As you can see, it's not a huge compressor (like some of the new 2-stage ones).
One of my room mates many years back, bought a big compressor, and tried to run it off the drier outlet. Which tripped breaker unitl it wouldn't reset.
A buddy who was an electrician tried a slower blow breaker, which didn't work.
He finally installed a magnetic starter, with properly sized "heaters", and fixed the problem.
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