How to Protect a Generator From an Electromagnetic Pulse

Protecting a typical 15,000 watt home generator from an electromagnetic pulse is both feasible and relatively inexpensive. The most reliable method is enclosing the generator in a Faraday cage. According to Clay Wilson at the University of Maryland, a Faraday cage “…routes damaging electromagnetic fields away from highly sensitive electrical components." Also used to guard against the more common threat of lightning strikes, a Faraday cage constructed from readily available materials can be a wise investment for the common homeowner.

Building the Base

1. Dig a 6-foot-by-6-foot foundation 6 inches deep using the shovel, taking care to keep the bottom surface even. Check periodically by placing the bubble level flat on the ground in several different positions. The bubble should stay within the two vertical lines on the face of the level.

2. Center a 6-foot-by-5-foot sheet of aluminum flooring in the foundation hole. Test each corner with the bubble level. If the flooring is not level, pull it up and use the shovel to even out the foundation. The flooring can remain loose, as the weight of the generator will keep it in place.

3. Cover all 6 feet by 5 feet of exposed aluminum with at least one layer of copper sheeting, attaching the copper sheeting to the aluminum with copper nails spaced 3 inches apart along the edges. This will provide the main barrier against EMP effects.

4. Affix the copper mesh over the copper sheeting to provide an additional layer of protection using copper U-nails spaced every 6 inches along the edges.

5. Place a 6-foot-by-5-foot covering of switchboard matting onto the aluminum-copper floor. This material will act as a non-conductive barrier between the generator and the Faraday cage.

6. Move the generator onto the platform, leaving at least 2 feet of clearance between the generator and the edge of the platform. Ensure that the generator touches nothing but the switchboard matting.

Enclose the Generator

1. Lay out two 6-foot-by-6-foot and three 6-foot-by-5-foot sections of aluminum sheeting. The 6-by-6 sheets will become two walls and the 6-by-5 sheets will make up the other two walls and the roof.

2. Cover all exposed aluminum on what will be the interior side with at least one layer of copper sheeting, and attach the copper sheeting to the aluminum with copper nails spaced three inches apart along the edges.

3. Affix the copper mesh over the copper sheeting using copper U-nails spaced every 6 inches along the edges.

4. Erect the walls around the generator, using the powered screwdriver to attach each wall to the floor and each wall to adjacent walls with the L-brackets spaced 1 foot apart, secured with 1/4-inch metal screws. If necessary, cut away part of the switchboard matting to place the L-brackets flush against the floor and wall.

5. Attach the roof to the walls using L-brackets spaced 1 foot apart anc secured with 1/4-inch metal screws.

Ground the Faraday Cage

1. Pound the grounding rod with the hammer 3 feet into the soil at least 6 feet from the enclosure and any other grounding rods or electronic equipment.

2. Wrap the copper wiring around the base of the grounding rod at least 10 times.

3. String the copper wire from the grounding rod to the Faraday cage.

4. Nail the copper wire securely to one side of the Faraday cage with at least three U-nails.