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

Topic Options
Rate This Topic
#70810 - 10/13/06 05:27 PM Tempest/faraday info
JCooper Offline
Registered: 12/30/02
Posts: 228
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?
Work Gear for Electricians and the Trades
#70811 - 10/13/06 05:29 PM Re: Tempest/faraday info
iwire Offline
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
I just use tin foil bed sheets.
Bob Badger
Construction & Maintenance Electrician
#70812 - 10/13/06 05:59 PM Re: Tempest/faraday info
NJwirenut Offline
Registered: 09/15/01
Posts: 806
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:

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.
#70813 - 10/13/06 08:37 PM Re: Tempest/faraday info
renosteinke Offline
Cat Servant
Registered: 01/22/05
Posts: 5316
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."
#70814 - 10/14/06 11:51 AM Re: Tempest/faraday info
gfretwell Offline

Registered: 07/20/04
Posts: 9039
Loc: Estero,Fl,usa
What are you trying to protect against. That will make the difference in what you need
Greg Fretwell
#70815 - 10/16/06 05:44 AM Re: Tempest/faraday info
SteveFehr Offline
Registered: 03/19/05
Posts: 1195
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.
#70816 - 10/16/06 08:29 AM Re: Tempest/faraday info
Almost Fried Offline
Registered: 09/04/06
Posts: 98
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...
#70817 - 10/16/06 08:34 AM Re: Tempest/faraday info
earlydean Offline
Registered: 12/22/03
Posts: 751
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.
#70818 - 10/16/06 07:36 PM Re: Tempest/faraday info
RobbieD Offline
Registered: 02/23/03
Posts: 231
Loc: Canada

Member Spotlight
Member Since: 12/24/00
Posts: 4259
New in the Gallery:
SE cable question

2017 NEC and Related
2017 NEC
Now Available!

Shout Box

Who's Online
0 registered (), 55 Guests and 9 Spiders online.
Key: Admin, Global Mod, Mod
New in the Gallery:
SE cable question
Top Posters (30 Days)
Admin 47
HotLine1 43
gfretwell 19
Ruben Rocha 12
Trumpy 9
Newest Members
Scotto, Freecrowder, clee512, Jdscott2005, FAIZAN

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