Sparkee:
Going back in time our POCO's did not allow an LB or any other 'openable' fitting in a service before the meter. Exceptions were granted with stipulations that the screws or other fastners were 'inoperable'. Filing the screw slot, or using one-way screws were acceptable. Recently, there has been no objections to LBs or other fittings.
Basically, it was a way the POCO could prevent 'unmetered' use of power, by a "tap" before the meter. Over many years, I saw a few 'taps'; and a few fires resulting from same.
Ask your dad if that may be his reasoning please.
