34.8 million real visitors so far... serving you since 2010.

A few reader questions regarding an EMP

April 5, 2012, by Ken Jorgustin

Reader Questions: (regarding an EMP)

A well motor..185 feet down..survive A EMP attack? …..(would have Have electricity)

Inside Old refrigerator ..good for EMP protection?

Extension cords..rubber..safe EMP?

I have heard that any early model (with carburetor) vehicle will be ok but will it effect the coil, points etc?

Answers (based on assumption of a severe EMP):

Well Pump Motor
I believe that a well motor pump ‘may’ still be vulnerable because of the fact that electrically induced currents from the EMP will travel throughout the electrical power grid, even finding its way down the wiring of a well shaft. Here’s why…

The EMP will induce currents in electrical wiring that is above ground, wiring that is acting like an antenna (the power grid), absorbing the very fast pulse transients.

“In 1831, Faraday and Henry discovered that a moving magnetic field would induce current in an electrical conductor. This process of generating electrical current in a conductor by placing the conductor in a changing magnetic field is called electromagnetic induction or just induction. It is called induction because the current is said to be induced in the conductor by the magnetic field.”

In the case of an EMP, the primary conductor is the electrical power grid (along with countless other smaller ‘conductors’ above ground; e.g. electrical circuits and semiconductor junctions of electronic devices), and the electro-magnetic-pulse transients are the ‘magnetic field’. The current induced in the grid and electrical systems from the EMP may be enough to overload and burn out power grid transformers and destroy semiconductor junctions of electronic devices.

In the case of the well pump motor (which contain many windings of wire), since the electrical power that feeds the motor is sourced from the grid, the current will still be instantaneously transient at the pump motor and associated circuits. Although most well pump motors have overload thermal protection, the pulse will be too quick for it to be effective. The question becomes, will the induced current be high enough to damage the motor windings. I can’t answer that, not knowing the proximity to ground-zero and many other variable parameters. My instinct tells me that the basic motor itself may survive, but any associated controller electronics will be zapped. And of course, the power grid itself will probably go down – rendering the entire system useless anyway.

Old Refrigerator
Yes, I believe an old refrigerator would make a fine EMP barrier, a Faraday Cage of sorts. A key factor will be to line the interior with cardboard (or some other insulating material) to ensure that whatever you are protecting inside of it does not touch the metal walls.

Extension cords
All extension cords will act as a big antenna to pick up the EMP, regardless of its insulation type. However, a self contained system of wiring that is not connected to the grid, and is entirely routed within metal electrical conduit pipe, properly grounded, would not act as an antenna and would not carry an EMP transient to the electronics connected to it. The caveat is that all connected electronics would themselves need to be contained within an electrical barrier system (Faraday Cage).

Early model vehicles
Any vehicle built early enough without electronic ignition, electronic sensors, and computers, ‘should’ survive an EMP. I say ‘should’ because even these vehicles have an alternator, voltage regulator, and distributor coil. A vehicle will be somewhat less susceptible to EMP because it is not connected to the power grid (the major ‘carrier’ of the pulse) and the inner workings are somewhat protected by metal (except of course today’s ‘plastic’ cars).

A car with ‘points’ and no computer will be fairly EMP resistant. Most pre 1975 cars were this way.