[Scan-DC] Topic drift on RF interference

[Blair Thompson]

I believe you used to be in Kuwait. I'm guessing this is a VOA antenna assembly. For workers in the U.S. there's an OSHA standard that covers that situation. I Googled and came up with this:

Radiofrequency Energy Poses Unseen Hazard
http://ehstoday.com/safety/electrical/ehs_imp_36029

"Standards

Though not commonplace, this situation has happened enough times to warrant an OSHA standard 29 CFR §1926.550 (a) (15) (vii), Cranes and Derricks:

'Prior to work near transmitter towers where an electrical charge can be induced in the equipment or materials being handled, the transmitter shall be de-energized or tests shall be made to determine if electrical charge is induced on the crane. The following precautions shall be taken when necessary to dissipate induced voltages:

1926.550(a)(15)(vii)(a) "The equipment shall be provided with an electrical ground directly to the upper rotating structure supporting the boom;" and

1926.550(a)(15)(vii)(b) "Ground jumper cables shall be attached to materials being handled by boom equipment when electrical charge is induced while working near energized transmitters. Crews shall be provided with nonconductive poles having large alligator clips or other similar protection to attach the ground cable to the load.'"

The page is dated December 12, 2002. They're referring to the old Part 1926, Subpart N of OSHA's Construction regulations. A new Cranes and Derricks Final Rule was issued in August 2010:

http://www.osha.gov/FedReg_osha_pdf/FED20100809.pdf

It's easier to read in the Electronic Code of Federal Regulations:

http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&SID=756fdc225f181309b73d134cefbdca3e&rgn=div6&view=text&node=29:8.1.1.1.1.28&idno=29

Go down to § 1926.1408(f)(1) and (2), Power line safety (up to 350 kV)—equipment operations:

"(f) When working near transmitter/communication towers where the equipment is close enough for an electrical charge to be induced in the equipment or materials being handled, the transmitter must be deenergized or the following precautions must be taken:

(1) The equipment must be provided with an electrical ground.

(2) If tag lines are used, they must be non-conductive."

Yes, it's under power line safety, which isn't entirely correct, but there you have it. Also, there's less material in the new standard than in the old, which seems contrary to one's expectations.

Hat tip to someone in OSHA's Construction office, who is one those People Who Know Right Away Where Stuff Like That Is Found. I talked to him not a half hour ago.

As for the spelling of "de-energized" as "deenergized," that's what the GPO Style Manual says it should be. I don't like it, but there's nothing I can do about it.

---------- Original Message ----------
From: Sheldon Daitch <SDAITCH at bbg.gov>
To: "David  Jones" <djoneses at verizon.net>, Rick Hansen <Rick.Hansen at apsglobal.com>, 'Doug Kitchener' <oldsdoug at yahoo.com>, "Scan-DC at mailman.qth.net" <Scan-DC at mailman.qth.net>
Subject: [Scan-DC] Topic drift on RF interference
Date: Thu, 9 May 2013 06:56:07 +0000

....
One area where we have had some issues with RF "interference" is at 
a location or two where neighbors had operating cranes.  At one location
where we had a 1000kW MW transmitter, the port folks about a mile away
would occasionally complain about arcing when they didn't properly ground
their lift equipment.  
....

73
Sheldon
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