Q: I am being told by a building engineer that low voltage cable cannot be attached (i.e. wire-tied) to existing conduits in the hospital. In ten-plus years in this business I have never heard of this being a problem. Is there any way to confirm this is a code violation?
A: Yes, I’m afraid this is true. Section 22.214.171.124 (section 126.96.36.199 for new healthcare occupancies) of the 2012 Life Safety Code requires compliance with section 9.1 which in turn requires compliance with NFPA 70 National Electrical Code, 2011 edition. Article 300.11 (B) of NFPA 70 does not permit anything to be attached to conduit, with one exception: Class 2 control cable may be attached to the conduit if it serves the circuit in the conduit.
Apparently, the concern that NFPA has is heat from the electrical conductors inside the conduit may not dissipate adequately if there are additional cables and wires tied to the outside of the conduit. While it is highly unlikely that a single low voltage cable that is wire-tied to a conduit would cause a problem, I guess it is logical that many wires and cables could be a problem. The question is where do you draw the line? I guess NFPA draws the line at one (1). So, I’m sorry to say, you will have to remove all the wires and cables from conduits in order to be compliant with the LSC. And by the way, do not attach those wires to your sprinkler pipes, either. That will cause a whole bunch of problems that you don’t need.