Steven M. Bellovin wrote:
In message <20050914184430.GA54042@mighty.grot.org>, Aditya writes:
The short-term solution seems to be using the APC PNET1s/Tripplite DNET1/etc. in each unit and tying them to the water main as an inexpensive, immediate step while funds are allocated for conduit, labor etc..
If I recall correctly, the National Electrical Code was change about a dozen years ago to bar grounding to water pipe unless it's within about 6' of where the pipe enters the house.
--Steven M. Bellovin, http://www.cs.columbia.edu/~smb
The change was in the 1993 NEC and restricts using water pipe as a ground to being within 5 feet of the point of entrance to the building. There is an additional requirement that the water pipe must be metallic and have a minimum of 10' buried in the ground. This can be hard to verify on existing installations due to the common use of plastic water pipe by utilities in recent years. The 5' from the point of entrance is also due to the common use of plastic water pipe in buildings. -- Mark Radabaugh Amplex mark@amplex.net 419.837.5015