HomePlug AV (HPAV) was designed to provide high speed in-home communication with 200Mbps PHY rate, with the goal to overcome various noises over power wires and to jump from one phase to a neighboring one. A HomePlug AV Logical Networks (AVLN) is defined by cryptographic means, i.e. stations that share the same key and hear each other are in the same AVLN; however, AVLNs which coexist in a neighborhood cannot communicate but share the same physical layer. These points imply that people using HomePlug AV may share system throughput with neighbors without being aware of it. In order to assess the reality of this potential problem, we performed measurements on an experimental testbed with several AVLNs and equipment from different manufacturers. Our results are: 1. we verified that HomePlug AV stations can communicate even over physically separated wires, and thus neighboring stations in the same AVLN or in different AVLNs may share the same throughput; 2. when stations are placed in two different AVLNs, system performance is noticeably less compared to having the same stations at the same locations but in one single AVLN; 3. HPAV stations from different manufacturers do interoperate but experience heavy per-pair throughput outages. Our findings suggest that HPAV does not perform satisfactorily in large deployments. A possible solution to the problem would be to make different AVLNs quasi-orthogonal at the physical layer, perhaps using the cryptographic key to seed an OFDM hopping sequence.