This isn't true. Under California law, PG&E are fully legally liable for any fires caused by their equipment even if they have fully and properly maintained it.

This isn't true. Under California law, PG&E are fully legally liable for any fires caused by their equipment even if they have fully and properly maintained it. This is called "inverse condemnation" and absolutely no negligence is required. (As it happens their maintenance has been rather dubious, but that doesn't affect their legal liability in any way.) If I remember rightly, the case which set this precedent involved a fuse correctly failing open and managing to set fire to some brush beneath the pole which had grown up in a few months since they'd cleared the entire area around it. There is no maintenance standard they could follow that would protect them from liability; all they can maybe hope to do is decrease the number of fires and the consequent costs somewhat.