Also, the O/P said the complainer simply said I CAN NOT USE. not why,, a bit of What happened would really help.. I will explain (And by the way I forgot one thing in my tester panel above.. VOLTAGE METERS you need two of those too, one for each side of the box)
First: If the Complainer had a "Surge Protector" Such as a Progressive Industries HW-50C and the outlet he plugged in was a long way from the distribution box, a long way to power.. And the electrician who wired it used the MINIMUM wire size for 50 amp.. Well the voltage drop when sucking major power could have shut him down.
The outlet would still check out as good on a straight voltage test
120-0-120
240---240
But.. with say a 40 amp load that 120 could become 110 or even 100 (And 100 will shut down an HW-50C)
THIS, is why I designed a test board up above.
As I said on each leg, put 4 space heaters (By building a proper test panel) and a volt meter, you should not see a significant voltage drop
Test both legs (you may test one at a time)
