#Power
Shared Neutrals Across Transformers: Why Phase Balancing Is Not Enough
A case involving two transformers with interconnected neutrals and houses tapped into one side's main feeder, leaving phase A 30-40 A higher even on days off, plus a meter-reading trap that can suggest a 200 A difference if the CT ratio is not verified first, and a repair sequence that must be followed in order.
Sizing Main Cables and Breakers by Installation Method
Notes on choosing the main cable and breaker for a new 253 A feeder, why the same size CV cable can carry 227 A or 364 A depending on how it is installed, and the option of downsizing to 95 and compensating with operating rules, at the cost of the main breaker tripping if anyone breaks those rules.
Diagnosing Feeder Overload from Melted Insulation and Duty Cycles
My investigation of a 95 mm² main cable with insulation melting at scattered points even though the system seemed to work normally, from the nameplates of 6 washers and dryers totaling 234.7 kW to a minute-by-minute current model explaining why a 482 A load on a cable rated for 180 A had not caused a visible system failure.