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My prior question asked about a single wire earth return [SWER] system. Both questions are aimed at meeting the same end requirement but this is a sufficiently different method that many of the issues are different. Please review:

I now plan on running both hots out of a spare 20A 2 pole breaker of house panel, and will terminate 775 ft later into a 5KVA isolation transformer [Hevi-Duty HS5F5AS] to step down to 120V. Seems like this would negate the requirement to run a neutral or a safety ground, as I will create these at the secondary of the transformer.

Does this sound legal to code ? Location is Atlanta,GA Looks like a 2 cond 6awg aluminum cable will provide a 6% volt drop @ 15 amp load on the primary/240V side.

Thanks for article @JONK March 8th, on grounding between buildings. I think where the danger still exists with the isolation transformer is that on the primary side with only the 2 hot conductors; if one of the those conductors shorts to the transformer case, there is no path to the source ground to trip a circuit breaker on the primary side of the transformer. Also the local ground rod at the transformer secondary is not a good enough path to the source voltage to trip the primary breaker. So I need to also run a bare copper ground wire with my 2 conductor 6 awg direct bury cable. Another thought; even if the hot primary does short to the transformer case, one would not feel it for the same reason, there is no path back to the source ground with low enough resistance to flow any current. i.e. the case would float at 120V with no path to flow any current/shock anyone. Not safe per code, but just thinking of what would happen.

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  • \$\begingroup\$ You're more likely to get good answers to code issues on Home Improvement than here. Also, it will help to say what jurisdiction you're in. \$\endgroup\$
    – The Photon
    Mar 8 '20 at 4:02
  • \$\begingroup\$ Joe, try reading through this. It may help somewhat. \$\endgroup\$
    – jonk
    Mar 8 '20 at 5:25
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    \$\begingroup\$ This is quite different to the prior question. Trying to change the other to read as this one would make old input invalid. THAT asked about a 120 VAC SWER (single wire earth return) line. This asks about a 2 wire line feeding two "phases (180 degree relationship) and no neutral or ground. The FIRST needed a ground as a power return to work at all. THIS one does not need ground or neutral to work. What it needs to meet code is another issue. \$\endgroup\$
    – Russell McMahon
    Mar 8 '20 at 5:50
  • \$\begingroup\$ Just fir fun, and who knows: You can use a microwave oven transformer to make " a few KV". This can be fed via "a piece of wet string" (or a thin copper cable if you prefer :-)) with SWER or two wire feed. With an isolating transformer at each end it may even be able to meet code. Losses at SAY 2400 V compared to 120 are 400 times less for the same power level. At 2 x 120V feed it's 100 times less. People do actually do this. You can buy wire on eg AliExpress rated to a few kV (varies). If you can a 120V over transformer from eg 60V (two primaries in series) then eg 3 kV wire very safe [tm] \$\endgroup\$
    – Russell McMahon
    Mar 8 '20 at 5:54
  • \$\begingroup\$ IF you feed a 2 wire line from an isolating transformer you SHOULD be be able to meet code as ground and neutral are fully isolated. I'm in New zealand so YMMV. \$\endgroup\$
    – Russell McMahon
    Mar 8 '20 at 5:55
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Thanks for article @JONK March 8th, on grounding between buildings. I think where the danger still exists with the isolation transformer is that on the primary side with only the 2 hot conductors; if one of the those conductors shorts to the transformer case, there is no path to the source ground to trip a circuit breaker on the primary side of the transformer. Also the local ground rod at the transformer secondary is not a good enough path to the source voltage to trip the primary breaker. So I need to also run a bare copper ground wire with my 2 conductor 6 awg direct bury cable. Another thought; even if the hot primary does short to the transformer case, one would not feel it for the same reason, there is no path back to the source ground with low enough resistance to flow any current. i.e. the case would float at 120V with no path to flow any current/shock anyone. Not safe per code, but just thinking of what would happen.

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