The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Sprinklered equipment 26-008
by bigpapa
12/02/16 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
Wow, that was close!
by jraef
11/28/16 07:06 PM
Earthquake in New Zeeland
by RODALCO
11/27/16 11:25 PM
Calling all Non-US members!! (Non-US only)
by Tjia1981
11/27/16 06:33 AM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 13
HotLine1 9
Texas_Ranger 8
sparkyinak 7
Trumpy 6
Who's Online
1 registered (gfretwell), 129 Guests and 6 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#70810 - 10/13/06 05:27 PM Tempest/faraday info
JCooper Offline
Member

Registered: 12/30/02
Posts: 229
Loc: Kendall Park, NJ USA
I can't I can justify the cost for this but I was trying to figure out just how I can turn my entire house into a faraday cage. I can line the walls with copper mesh, drive a whole bunch of ground rods, convert cable & telco over to fiber outside the house, but there is one piece I can't figure out, power.

My question is this, can you isloate utility power from an EMP?

I thought about a natural gas genset, fed with plastic pipe of course, inside the 'cage'. Would a simple isloation transformer provide true isolation?

Top
Work Gear for Electricians and the Trades

Work Gear for Electricians and the Trades
Work Gear for Electricians and the Trades
Arc Flash Clothing, Gloves, KneePads, Tool Belts, Pouches, Tool Carriers, etc. etc....

#70811 - 10/13/06 05:29 PM Re: Tempest/faraday info
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
I just use tin foil bed sheets.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

Top
#70812 - 10/13/06 05:59 PM Re: Tempest/faraday info
NJwirenut Offline
Member

Registered: 09/15/01
Posts: 816
Loc: Bergen County, NJ
First of all, TEMPEST shielding and EMP suppression are not exactly the same thing.

TEMPEST has to do with reducing radiation FROM equipment which could be intercepted by someone on the outside. Involves a lot of heavy shielding, broadband filtering/bypassing, etc.

EMP suppression is for the protection of your equipment. It can be achieved by LC filtering and fast-acting impulse suppressors like these:
http://www.polyphaser.com/kommerce_productdata.aspx?search_val=NEMP&x=0&y=0

Yes, utility power can be bypassed and filtered where it enters a faraday cage. It is done all the time in screen rooms used for RF equipment testing.

Top
#70813 - 10/13/06 08:37 PM Re: Tempest/faraday info
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
In response to a similar query.. "how can I protect my electronics from EMP?", I recall the following expert advice being given:

"Place them inside a steel ammo box. Ste this box on a block of wood, inside a larger ammo box. If the EMP still damages your electronics, you are way too close to ground zero."

Top
#70814 - 10/14/06 11:51 AM Re: Tempest/faraday info
gfretwell Online   content

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
What are you trying to protect against. That will make the difference in what you need
_________________________
Greg Fretwell

Top
#70815 - 10/16/06 05:44 AM Re: Tempest/faraday info
SteveFehr Offline
Member

Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
There's an unclassified army manual for EMP-proof facilities design, EP 1110-3-2. All your answers are in there The amplitudes are completely different between EMP and TEMPEST and frequencies vary a little, but the level of attentuation and design for protection for both is practically identical.

To get 90dB attentuation, you can't just use tin foil, you have to use a significant thickness of steel or copper or another conductor, otherwise a significant portion of the EMP burst will transmit straighit through it and still come out the backside at reduced but dangerous levels. The thickness depends on the frequencies and desired level of protection, and of course the material being used- welded 1/4" carbon steel will provide this protection.

You can buy filters for power and communication lines that provide > 90dB protection.

Top
#70816 - 10/16/06 08:29 AM Re: Tempest/faraday info
Almost Fried Offline
Member

Registered: 09/04/06
Posts: 104
Loc: Madison County, Ark. USA
There is a cave in Newton County, Arkansas for sale for about 1.5 Million that should suit your requirements. You can't hide from all of it, forever, and then there are telemarketers...

Top
#70817 - 10/16/06 08:34 AM Re: Tempest/faraday info
earlydean Offline
Member

Registered: 12/22/03
Posts: 749
Loc: Griswold, CT, USA
Build your own with 4 foot thick reinforced concrete walls and ceiling, bonded to about 2 dozen ground rods. Power would be supplied by an on site generator, or a nearby set of batteries with inverter, which could be kept charged by the utility power.
_________________________
Earl

Top
#70818 - 10/16/06 07:36 PM Re: Tempest/faraday info
RobbieD Offline
Member

Registered: 02/23/03
Posts: 238
Loc: Canada

Top



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals