>Most informative, Jim.
>
>Follow-up questions concerning means and methods for
>testing and analysis of non-wire conductors, or contrarily,
>means and methods to prevent conduction by these
>systems:
>
>1. Metal ductwork systems.
Metallic duct work is best protected by using two or more dielectric
junction points on each segment of the ductwork. A removable coupler
is my preference to that it can be completely removed from
inspections and measurements.
I lean towards an insulated coupler that provides at least 10 inches
offset between each piece of ductwork, but 24 inches is better but
often impractical. The material should have at least 40 mega-ohms of
insulation per inch of length when the ambient humidity is 75%
It is always best to use all non-metallic/non conductive ductwork and
to pull it out periodically and re-install all new stuff.
>2. Metal plumbing systems.
Tough problem. Water is conductive, so using non-conductive plumbing
isn't going to help too much if the pipe are going to be wet.
Plastic/PVC pipes will work, but not well. If you absolutely need
plumbing you want to set up a dry pipe system so that water is not
present in the pipe unless called for. This is similar to a dry
sprinkler system where the water is drawn out of the non-conductive
pipes after use. A popular method is all thick wall glass pipes, or teflon.
>3. Structural steel systems including metal floor deck.
>
>4. Steel reinforcing grids in concrete floor and roof decks.
No joy, no joy at all. The reinforcing grid/rebar present in concrete
causes some pretty serious problems and nightmares for sweepers. The
cleanest way to deal with it is to interlace a single strand of
copper clad stainless steel wire rope into the rebar and to tack weld
it to the steel and then terminate it in a removable ground that the
TSCM specialist can get to during a sweep.
>5. Metal suspended ceiling and raised floor systems.
Go with a non conductive ceiling grid and supports, and solid,
non-hydroscopic tiles.
>6. Metal curtain wall systems which typically created a conductive
>grid, vertical and horizontal continuous past interior partitions, isolation
>systems and other means used within a structure to inhibit interception.
Better to go with a graphite epoxy honeycomb panel system.
>7. Smart, or intelligent, glazing systems which are energized to
>modulate for variable lighting and heating requirements. These are
>prevalent in latest curtain wall systems, with or without mullions, and
>may serve as unintentional conductors.
>
>Thanks for your response.
>
>There is at least one patented structural steel EM isolation system,
>and I have seen references to techniques for protection of traditional
>mechanical, electrical and plumbing (MEP) systems, but nothing
>so far on the latest building exterior metal and glass envelopes.
>Patents for those could be classified at birth, or just not made
>public.
>
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James M. Atkinson Phone: (978) 546-3803
Granite Island Group Fax: (978) 546-9467
127 Eastern Avenue #291 Web:
http://www.tscm.com/
Gloucester, MA 01931-8008 E-mail: mailto:jm..._at_tscm.com
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Received on Sat Mar 02 2024 - 00:57:17 CST