Hi Ghery,

Thanks for the clarification.  I know you had it built, so you know the 
dimensions well.  It is definitely a very large chamber, considering it had 
hundreds of 8 foot long RF absorbers within it.

Regards,

Manny Barron
EMC/EMI Engineer
Northrop Grumman Corp.
San Jose, California



From: Pettit, Ghery [mailto:[email protected]]
Sent: Friday, January 10, 2014 3:21 PM
To: Barron, Manny (IS); [email protected]
Subject: EXT :RE: Risk Assessments and mitigation for EMC chambers

Manny,

That chamber was "only" 30 feet high, not 40 feet.  :)

And Apple pulled all the absorbers out and re-lined it to make an antenna 
pattern chamber out of it.  I understand their RF guys are tickled to have such 
a LARGE chamber for that work.

I hope all is going well at Northrup Grumman for you.

Ghery S. Pettit

From: Barron, Manny (IS) [mailto:[email protected]]
Sent: Friday, January 10, 2014 3:09 PM
To: [email protected]<mailto:[email protected]>
Subject: Re: [PSES] Risk Assessments and mitigation for EMC chambers

The main safety concern we had at our older 10m chamber (~15 years ago, 
previous employer) - was 80 lb polyurethane RF absorber cones falling from the 
40 ft chamber ceiling.  Had 3 cones fall over a 4 year period (in 3 separate 
events, different parts of ceiling), all fell overnight when nobody was around 
(found the cones on the floor the next morning).  We all wondered if we could 
hear one fall and if we'd have time to see where it was falling from and have 
enough time to jump out of the way if necessary.  Yeah it was scary, and it got 
everyone's attention, all the way up the management chain.

After each cone fall event we had a contractor come in with a scissor lift to 
jiggle each ceiling cone to see if it was on the verge of coming loose (none 
were during those checks).  After the 3rd cone fall we had a contractor install 
a thick netting (nylon I think) over the entire ceiling up near the ceiling 
level.  It probably wouldn't stop the 80 lb cone from hitting the floor, but it 
would definitely delay it (hopefully providing some warning).  About a year 
after the net installation the entire lab was shut down (closed due to massive 
company layoff).  Escape from danger!

Whenever I walk into a room, even today, I tend to look up at the ceiling 
suspiciously.

Manny Barron
EMC/EMI Engineer
Northrop Grumman Corp.
San Jose, California



From: Charlie Blackham [mailto:[email protected]]
Sent: Thursday, January 09, 2014 12:39 PM
To: [email protected]<mailto:[email protected]>
Subject: EXT :[PSES] Risk Assessments and mitigation for EMC chambers

All

Client has performed risk assessment for turntables and high RF fields in their 
anechoic chambers and is looking at implementing emergency stops for the former 
and flashing lights warning of the later. (I've never seen flashing lights at 
other labs whilst witnessing tests up to 350 V/m, and the client chamber will 
only be used with amps < 250 W).

The turntable is not flush to the floor, so does present more hazard than some, 
and some operation does require people to be on or adjacent to the turntable 
for operation/maintenance.

There is already plenty of good "process" and supporting documentation and 
everyone with access to the chambers have already been through a thorough 
safety briefing.
Anyone have any documents or stories to share as to how they have 
satisfied/pacified/dismissed enthusiastic Health & Safety officers who still 
want to "do something"?

Regards
Charlie

Charlie Blackham
Sulis Consultants Ltd
Tel: +44 (0)7946 624317
Web: www.sulisconsultants.com<http://www.sulisconsultants.com/>
Registered in England and Wales, number 05466247

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