This may be up to your AHJ, but as I stated on another board, I think you should replace the cables & outlets or purchase service entrance equipment that has room for a couple of more 2 pole breakers & extend the 3 wire cables into the new service entrance box.

Although three wire feeds were allowed for these types of loads, they were not allowed to be fed from a sub-panel, which is what you will be doing when you upgrade the service.

The current requirement is 250-140(3). The old reference was 250-60(c).

Tom

[This message has been edited by Tom (edited 06-28-2001).]

Few things are harder to put up with than the annoyance of a good example.