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In a remote studio have a Sub-Pannel with Multimeter readings. With No Circuit Breakers In Place (L1 to N 120v) (L2 to N 120v) (L1 to G 120v) (L2 to G 120v) (L1 to L2 240v) (N to G 0v)

slim type circuit breakers (4 singles are for 120v) (2 doubles are for 240v) dryer and air conditioner

with all circuit breakers ON I found (L1 to N 240v)(L1 to G 240v) while the other L2 drops to 0v if i cutoff a certain breaker i find the problem to become vice versa (L2 to N 240v)(L2 to G 240v) L1 drops to 0v

My regular wall outlets show HOT to Neutral 240v

This problem raised out of the blue. All circuits had normal readings prior to 1 day ago and have not changed in 5 years. Had another electrician observe situation and was also stumped with no idea.

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    Turn off your 2 double pole breakers and take measurements. The only way to get 240v in a standard split phase system is when a inductor is center tapped with no load the other leg will create the voltage but I haven’t seen it go that high. – Ed Beal Jan 21 at 0:37
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    I'm sure one of the electrical-expert users will post a real answer soon. But from all the similar questions I've seen them answer previously, I will guess that you are suffering from a disconnected neutral to the panel (possibly the building). Depending on where the break is, could be a job for the power company. – Peter Duniho Jan 21 at 0:37
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    I may not have given the "best" duplicate, but basically: You likely have a lost neutral, CALL THE ELECTRIC UTILITY AND TELL THEM YOU HAVE AN OUTAGE. Meanwhile, turn off everything you can. It is urgent, and the electric utility will treat it as urgent (at least in the US). If they ask for specifics, don't go into all the details, just tell them "Things don't work and I think my neutral is lost." Multimeters are very senstive, so under no load they'll get the "right" answer - but under load the problem comes out and you see the messed up voltage. – manassehkatz-Moving 2 Codidact Jan 21 at 0:43
  • The breaker you are turning on has a load on it. Which is connecting neutral to that phase via the load. Since neutral is broken, it just pulls neutral to that voltage. – Harper - Reinstate Monica Jan 21 at 3:46
  • Ed Beal, i physically pulled out the 2 double breakers from the Bars at sub panel.. still get same issue.... its only when i fumble with the 4 slim single 120v breakers that i get changes... almost as if i got to replace the slim ones, but i don't make sense of the circuit travel.... I lost 2 ceiling fans and fridge blewout. phase A and phase B bars are normal without the single breakers in place. – Lester Ray Jan 21 at 20:43