home networking - city codes?

The new NEC based electrical code has a "low voltage" installer category. You need some kind of certificate to install networking, unless the system is "inherently safe". Under the new NEC based code you need a full flegded electrician to install a telephone line since it voltage goes over 48 volts when the phone rings. Also a licensed electrician has to install the risers and any wire harnesses for a low voltage system.

I don't think the city has figured out the qualifications for a "low voltage" installer yet so you can't actually apply for this qualification. I would assume they would want you to know you should use plenum cable when penetrating walls and should place fire barriers in the riser every so often. A way around this would be to install a no voltage network, i.e. fiber or wireless; you would still want to take the same fire safety precautions, but the network wouldn't be regulated by the electrical code.

Posted by: danielk at July 30, 2006 10:17 PM

FYI I looked over the code. It looks like it is just basic stuff for CAT-5/6 cable. You need plenum cable in plenums (air spaces) and risers (you can get away with cheaper stuff in risers, but why bother?). You need firestops on each floor in riser conduits. The work should be neat, without flying splices, etc. And you need to keep physical seperation from high voltage wires; which you want to anyway because of interference and induction currents. And any metal conduits must be properly grounded, which is probably why a master electrician is required to install conduits.

Also for antenna wire and cable tv wire there are some common sense grounding requirements; but I didn't even see a requirement for a lightning arrestor. I would not really consider these minimal requirements of the code here as being very safe with most equipment.

BTW I was wrong about fiber optic cable, it is regulated by the electrical code. You can't use combo/hybrid cable that has a low frequency conductor (aka metal) without the same precautions as you would with CAT-5/6 and the same rules apply to risers and conduits even if there is no metal in the cable, presumably because metal conduits could come into contact with the electrical system, and any conduit could help spread a fire if they didn't contain firestopping materal when they cross floors or penetrate firewalls.

Posted by: danielk at August 7, 2006 11:08 AM