DIYbanter - View Single Post - Can I plug my 230V compressor (NEMA 6-20P) into a dryer (NEMA 10-30R) receptacle?

wrote in message ...
| IMHO, it's actually SAFER for the OP to connect the compressor to the dryer
| circuit than it is for him to use the dryer!

May I try to summarize the current conscensus (by no means unanimous) as:
- We have a 3-wire 30 amp 240 volt dryer receptacle (NEMA 10-30R);
- And a 3-wire 20 amp 240 volt air-compressor (NEMA 6-20P) to run;
- The proposed solution will attempt to be 100% legal to code;
- The proposed solution will attempt to be as safe as existing equipment;
- The proposed solution will attempt to be as simple as possible;
- The dryer uses the "grounded" wire as a 125 volt "neutral";
- The compressor uses the "grounded" wire as a 0 volt "safety ground";
- The proposed use model assumes either the dryer or compressor in situ;
- Never will both be operated on the same circuit at the same time;
- The old-code dryer is connected to the main panel with no subpanel;
- The house is correctly wired to code (grandfathered for the dryer);
- The dryer plug (NEMA 10-30P) is NOT designed to be often removed;
- The proposed use model is temporary use (not more than 5 times/year);
- All recommend wiring a new compressor circuit as the best solution;
- Most (but not all) agree that a temporary patch cable will work;
- Some (about half) assert that a temporary patch cable is safe & legal;
- Normal operation of the dryer actually has some elements of risk;
- The risks elements include house-wire fire, dryer fire, & hot casing;
- Operating the compressor via a patch cable actually reduces some risk;
- Operating the compressor via a patch cable also increases other risks;
- The hot-casing risk is certainly reduced in the compressor situation;
- However the compressor equipment fire risk is increased somewhat;
- This additional equipment fire risk can be reduced with an in-line fuse;
- House-wire fire is most likely not of increased risk in either scenario;
- The biggest risk appears to be mechanical integrity of the NEMA 10-30P;
- Over time, that dryer plug will become less safe due to repeated use;

In summary, it appears:
- It's safe & legal to (rarely) run the compressor via a patch cord;
- But, it's better & even safer (long term) to add a new 6-20R circuit.

I want to do this summary correctly so others can follow our footsteps.
Did I summarize the results of the past 50 posts correctly?

MM