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Have not sized transformers for motor loads for a long time, but how many HP is your compressor? never mind I looked at your link 5hp 22A, looks like it is rated for 31A. The starting current for that compressor motor would be pretty high.
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06-06-2020, 10:26 AM
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I believe that rating is for the boost/buck portion of the transformer(12/24v)
Follow the link shaun posted and it's 30/60 amp.
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06-06-2020, 10:34 AM
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Pulled transformer apart, wiring is charred. No time for inspection. More to come.
Interestingly, the dryer did work plugged into it so it may be salvageable. Or not.
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06-06-2020, 01:03 PM
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first thought is undersized
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06-06-2020, 04:30 PM
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So would there be a benefit to oversizing a transformer for longevity purposes?
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06-06-2020, 04:40 PM
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Quote:
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06-06-2020, 04:41 PM
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I'll post some pics tomorrow of the wiring.
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06-06-2020, 04:48 PM
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X2 and X3 got mighty hot.
  
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06-07-2020, 04:23 AM
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I think you can save it. It should be hi-potted to be sure it's okay.
Put a fan on it when it runs next time...and a cooling plate too if needed.
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06-07-2020, 05:25 AM
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The wires actually look good to the transformer. Looks like (from hundreds of miles away) this connection in this spot arced and failed:
 Looks like the smoke released from the connections, not the transformer. If you want to test the transformer, you should get a 'continuity' reading for each individual coil to see if it burned open. Disconnect all the wires, with an ohmmeter there should be able to get a measurement at each coil (greater than infinity). X1 & X2, X3 & X4, H1 & H2, H3 & H4. The 2 X coils should read about the same, as should the 2 H coils.
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06-07-2020, 08:02 AM
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Thanks '90 and Dad.
The failure is at the junction of X2 and X3. That junction burned the connector off and melted away the exposed twisted wires. 
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06-07-2020, 08:09 AM
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 What gauge is this wire? How many amp breaker on this circuit? Based on the Compressor specs, should be 30A breaker, and wire at least 10AWG.
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06-07-2020, 08:09 AM
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Just looked, it's 12/3 solid Romex.
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06-07-2020, 08:14 AM
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Quote:
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06-07-2020, 08:15 AM
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Any idea why it did what it did? Should I at least get the 10/3 wire?
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06-07-2020, 08:21 AM
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The compressor specs say it draws 22 amps, and recommend a 30 amp breaker, which would typically be #10 wire. If it's a long way to the panel, or if there is a 20 amp breaker on #12, you should probably address this.
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06-07-2020, 08:25 AM
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it's a 30A breaker. A professional electrician ran the wire 60 feet or so from the box to the new outlet which was for a silkscreen exposure unit. I think it had a 4500W metal halide bulb. Took massive amounts of e-. The brightness was incredible. I will have to look at what gauge wire the electrician ran.
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06-07-2020, 08:29 AM
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The transformer is next to the outlet with the compressor.
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06-07-2020, 08:38 AM
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I didn't sleep in a Holiday Inn, and I'm more familiar with Residential than Commercial, but in general the wire is sized for the load, then a breaker is sized to protect the wire, if that makes sense. #12 is generally rated for 20amp, #10 for 30amp (copper). The specs for the compressor say 22 amp, 30amp breaker. If you have been getting by not tripping a 20 amp breaker, and it's a short run to the panel, you can probably leave well enough alone. If it's a 30 amp breaker on #12 wire, that's not allowed residential, and I suspect commercial also. If it's a long run to the panel, you would also get less voltage drop with #10 wire.
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06-07-2020, 08:53 AM
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So the #12 just goes a few feet from transformet to the outlet? Definitely swap.
If I was closer I'd grab a hunk of wire and come over.
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06-07-2020, 08:57 AM
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1987 930
2013 KTM RC8R
1999 BMW R1100s
1987 BMW 535i
