We have an old apartment building. It is wired with two-prong outlets fed by two-wire cable (hot and neutral, no ground).

When I test these outlets using a pen-style tester (the kind that "senses" current without actually touching the wire) both side give a hot reading.

The outlets work fine otherwise (appliances plugged into them work).

When I test the outlets in my home (with grounded outlets) one side tests hot, the other doesn't.

What's happening with the older outlets? Is this a problem that needs to be fixed? If so, how? Hopefully not by rewiring the entire building.

Thanks,

John