If you haven’t read Part #1 of this 2-part series you probably should.

< click here to read Part #1 >

My Protection Strategy –

So how do I protect my off-grid home?

First off…I place a more likely chance that I will suffer a lightening strike than an EMP. However, I don’t discount the occurrence of an EMP strike on the continental US, and that has the potential to affect our home. Remember I am off-grid so I don’t have thousands of miles of electrical transmission lines attached to my house. That my friend greatly reduces my exposure to an incoming EMP surge.

All that being said I take some basic precautions first…

1. My PVs (solar panels) all have aluminum frames, all those frames are attache to an earth ground system. The earth ground system includes:
   1. A single continuous 8AWG bare copper wire connected to each panel of 3 PVs in the string via a lay-in grounding lug.
   2. The 8AWG bare copper wire from each string is connected to a 6AWG bare copper wire handling the array that contain 2 strings each.
   3. The two main arrays (#2 & #3) are connected via 6AWG bare copper wire to an earth ground that consists of three 8’ copper clad rods driven in the ground 10’ apart bonded with 6AWG bare copper. Note1: the arrays are approximately 50’ apart and the 6AWG bare copper wire connecting the two arrays are buried 12” in the ground between the two arrays. Note2: the third array is grounded separately to its own earth ground that is also the house system earth ground. Again, it consists of three 8’ copper clad rods driven in the ground 10’ apart bonded with 6AWG bare copper.
   4. Each array also has a 40ka surge protector in the EcoWorthy combiner box. That surge protector is connected to the 6AWG array ground wire. The combiner box is a Chinese manufacturer and I don’t know if it will work or not when the times comes. The SPD was included with the boxes when I bought them.
   5. This gives two types of surge protection; 1) any energy absorbed through the PV metal frames is directed into the ground, 2) any energy absorbed into the PV wiring is directed to the external combiner box’s SPD and that energy is directed into the ground.

2. The utility room that houses the solar/electrical/electronic equipment has a metal roof and foil backed OSB on the side walls. I have no idea whatsoever if this provides any protection. Some folks think so, others don’t. I don’t count on it.
3. Inside the utility room the incoming PV power lines come into separate array disconnect boxes. Each disconnect box has a Midnite Solar MNSPD-300-DC (80ka) installed.

I consider this to be my lightening strike/surge protection (E2 & E3); 1) good grounding, 2) a 40ka SPD, and 3) an 80ka SPD. But that stills leaves out the EMP E1 power surge. To address that issue you have to go downstream of my system.

Downstream of the array disconnect boxes I have a combiner box that combines arrays into a circuit breakers that also acts as disconnects. that is located just before my charge controllers. Arrays #1 & #3 go into my charge controller #1, and array #2 goes into my charge controller #2. For the E1 surge I have an EMPShield model Dual-DC-90-120-W. Each charge controller has its own protection via this EMPShield unit since it is a “dual” unit. And yes, the EMPShield unit also provides E2 & E3 protection.

And how good is the EMPShield? Well, that is hard to say. Remember, we have no definitive idea if a device works, or not, until an event occurs. But, the documentation on the EMPShield device, along with the advertised testing, assures that it will protect against E1, E2, & E3 power surges. So that combination of surge protectors protects against surges coming into the system from the outside via the DC side of my off-grid solar system.

Now let’s talk the AC side of the system…I also have a Midnite Solar MNSPD-300-AC installed in my main breaker panel. That is intended to protect power surges getting into the system via house wiring. Yup, that means every single inch of wire in the house is a potential “antenna” for power surges. And yes, that means I am only protected against E2 & E3 surges from the AC side of the system. It is my intention that as my research continues and I become 100% convinced of EMPShield products I will install one of their AC units in the main breaker panel and move the Midnite Solar SPD to the inverter/generator transfer switch.

And if you are wondering…I have no problems with an Siemens FS140 (FirstSurge) being used as a substitute for a Midnite Solar SPD. I use Midnite simply because I found it first and have confidence in it for lightening protection.

How an SPD works –

If you are wondering how a SPD works…well, that is another whole article. But the short version is this…the SPD draws the power surge into itself away from other wiring and equipment and dissipates it through its internal parts. Yeah…call it magic, voodoo, or a modern engineering marvel…but that’s how they are designed to work.

Now, have you asked the question yet…Will all of this work and protect my house full of electronics/electrical equipment, and better yet, will it protect thousands of dollars worth of my solar system gear? If you have an answer let me know!

Yeah, a funny way to say I have no idea if this will all work to save me from an EMP, let alone a lightening strike. But I do know that doing nothing will definitely result in a bunch of burned up and useless equipment.

I will write reviews on EMPShield and Midnite products fairly soon. Should you buy now? Well…I did. And doing something is better than doing nothing. Do nothing ensures failure.

< click here to read Part #1

If you are interested in buying any of the mentioned products…PLEASE DO 🙂

I am providing links to the equipment below. If you buy one of the Amazon products through my link I will earn about a 1.5% commission. If you buy an EMPShield product I will earn a 15% commission. And if you use the coupon code “ahtrimble” when you buy an EMPShield product on their website you will get $50 off any product.

Any money I earn will go towards a test unit for the AC side of the system. If I earn more than the cost of a test unit then any excess funds will go towards another LifePO4 battery.

Click on the icon below for the MidNite Solar 300vDC unit (for protecting DC voltage equipment)…

MidNite Solar MNSPD-300-DC Surge Protection Device (300vDC )

Click on the icon below for the MidNite Solar 300vDC unit (for protecting AC voltage equipment)…

MidNite Solar MNSPD-300-AC Surge Protection Device (300vAC )

Click on the icon below for the Siemens FS140 Whole House Surge Protection…

Click on the EMPShield logo below  to buy EMPShield products. Use “ahtrimble” in the coupon code at check out for $50 off any EMPShield product. Hint: If you are buying more than one product then make them separate purchases and use the coupon code for each. If are having trouble deciding which product to buy, then write a comment below and ask for help from me.

Related Articles –

• Protecting your Radio from an EMP: Part #1
• Will we really be hit with an EMP? (part #1)
• Threats, Risk, Matrix, Mitigation: Introduction

 2009 - 2023 Copyright © AHTrimble.com ~ All rights reserved
No reproduction or other use of this content 
without expressed written permission from AHTrimble.com
See Content Use Policy for more information.

Time to go technical…’high-tech’ to be exact…let’s talk surge protection.

For this discussion surge protection will include the concepts of lightening strikes (LS), Coronal Mass Ejections (CME), and of course, Electromagnetic Pulses (EMP). While they do differ, they all can be a threat to electrical and electronic equipment. Additionally, I won’t go into detail on protecting small devices such as handheld radios since I have already covered that in the past. I will concentrate on covering entire systems such as home AC electrical systems and solar systems (both AC & DC sides).

As with all my articles regarding equipment/gear I define the mission, or job, that I want that equipment/gear to accomplish. For this I define it as…

“Reasonably, effectiveness & economically, protect our home’s complete electrical systems from damage due to electrical surges regardless of their origin.”

Also, when you hear me refer to a SPD, I am talking about a ‘surge protection device’.

Now that’s done let’s talk about risk management. As I have previously written extensively about risk management, it is determining the probability of an event occurring, and if it does occur, how severe will the potential damage be. Once those two criteria are properly assessed then proper mitigation measures can be identified and undertaken.

In my original article “Will we really be hit with an EMP?”, written in 2015 and updated in 2019, evaluated and stated both the probability and severity values. I originally set the probability at ‘very low’ and the severity as ‘nationally devastating’. Numerically speaking now I would go with 4 – 5 for probability (moderate) and 9 – 10 for severity (nationally devastating).

For the purposes of this article I put the CME events at a ‘moderate’ in severity and ‘low ‘in probability. And then for lightening I go with ‘serious’ in probability and ‘devastating’ in severity. And then somewhere in here I have to inject a healthy dose of reality. I don’t it is feasible at all to ‘harden’ my entire house and all associated electrical and electronic items against all possible surge events. I simply don’t have them time, the expertise, nor the money to do so. And honestly, I don’t have the desire to. I want to live in reality and not acquire a bunker and/or siege mentality out at the fringes.

So let’s talk the most likely of the surges involved with the most potential of severe damage…EMP.

EMP’s are a result of a high-altitude nuclear detonation. Modern nuclear devices that would be used in an EMP strike consist of three waves of energy pulses; E1, E2, & E3. Now, I am not going into intense details…it would make everyone’s eyes glaze over. There are plenty of articles on the subject if you want to get that far into the weeds.

EMP information, generally speaking…

• EMP devices are generally detonated high in the atmosphere so the damage can cover large areas of earth’s surface.
• The detonation effects spread out in all directions but the earth attracts most of the energy pulses downward.
• The higher the detonation the lessening of the pulse energy.
• The further away from directly underneath the detonation the lessening of the pulse energy.
• In North America the energy pulses are drawn more to the south of the detonation point due magnetic field and orientation to the equator.

E1 Pulse –

This first pulse of energy does most of the damage in systems. It is primarily high-voltage that does the damage. This first pulse of energy travels at about 90% the speed of light (about 168,000 miles per second) and peak energy is about at the 5 nanosecond mark.

Realistic Example: You are 250 miles from a EMP blast, that means it hits you in about 0.0015 seconds (15 thousandths of a second) but traveling at 168,000 miles per second, and once it hits you, the peak energy arrives in 5 nanoseconds. So once the energy hits you, the energy goes from 0% to 100% of peak withing 5,000,000,000ths of a second. And the pulse has passed you in about 100nanoseconds. Meaning you have to protect your systems quickly, approximately within a nanosecond, and for about 20nanoseconds.

The voltage that actually reaches a maximum of about 50,000volts per square meter. Meaning, if you had a 1 meter square steel plate sitting on the ground directly beneath the detonation point the steel plate would absorb 50,000volts. If what was struck was a normal 3-wire household service cable 100’ long from the electric pole to the electrical service entrance it would absorb about the same 50,000volts. Ironically, the amperage would only be less that 50amps for that same area…but only for far less than a second.

As you can see it is the absorbed voltage that will do the damage but it occurs very, very quickly. And that is why normal residential, and even commercial, surge protectors simply won’t provide protection…they can engage/react quickly enough…about 500-1000 times too slow to react to the incoming energy surge.

E2 Pulse –

This is the next energy pulse to hit…about 1000nanoseconds after the E1 strike, and 900nanoseconds after the E1 is gone. And the reaction speed required is about a microsecond. Yeah, slowpoke!

To get a grasp of this energy pules you can think in terms of a lightening strike. And also think of it in terms of DC voltage. The power can reach 100,000 volts and 100,000amps when it hits…depending on your relative location to the detonation. And surge protection devices such as Midnite SPDs can handle this kind of strike..essentially a lightening strike.

Here’s the problem…that same SPD would get burned out by the initial energy surge…the E1…so it is no longer available to handle the E2 energy surge…and your system is pretty sure to now damaged.

E3 Pulse –

The final energy surge is just plain weird! The energy surge is produced by the earth’s magnetic field being heaved about. And that surge can last from 10 – 100’s of seconds. To get an understanding of this pulse…think DC current. Unfortunately household systems, including power stations and transmission equipment are designed to handle AC current not DC current. That gets you a whole lot of burned out equipment.

Once again E1 pulses normally burnout SPDs that could have handled this E3 power surge.

Pulses Summary –

Whew! I am glad that is over. But the summary is pretty simple, 3 different pulses of energy, all 3 can destroy equipment, and the first pulse is the worst and generally destroys any device (SPD) that could prevent damage from the 2^nd and 3^rd pulses. And yes, generally speaking almost all SPDs in use today can’t handle the E1 pulse. So you’re screwed right? Ah, no.

Remember, most common SPDs can’t protect against an E1 pulse…they burnout with all your other electrical/electronic gear. But, most common SPDs are fairly inexpensive…about $125 – $150 range for Midnite SPDs. The commercial grade SPDs can hit $300, but they still are too slow to protect against the E1 pulse.

That means something rather simple…You gotta find E1 protection if you are going to be worried about EMP protection. If you are going for less protection against energy pulses, such as lightening protection, then a Midnite Solar SPD or the more expensive Siemens FS140 are great options.

Next comes what I do!

NOTE: In Part #2 I will give links to various products that I personally use and believe in. And if you purchase a product through one of those links I will make a bit of money…from 2% – 15%. The money I make from any of those purchases will go towards a new battery for my solar system. And I can offer a $50 off coupon for the #1 EMP surge protection device!!!

< click here to read Part #2 >

Related Articles –

• Protecting your Radio from an EMP: Part #1
• Will we really be hit with an EMP? (part #1)
• Threats, Risk, Matrix, Mitigation: Introduction

 2009 - 2023 Copyright © AHTrimble.com ~ All rights reserved
No reproduction or other use of this content 
without expressed written permission from AHTrimble.com
See Content Use Policy for more information.