TRANS EMP prep?

Big Bob

Senior Member
I was thinking today. Many years back there was
Much discussion on this board about EMP.

With all the Sabre rattling in the mid east perhaps it may be good to review preps.

I had the idea to disconnect a vehicle battery and discharge any components through a test light. Then connect the main leads together and run a heavy jumper cable to both the vehicle frame and electrical system to driven ground rod.

I figure this wouldn’t cost anything and might help save a vehicle in such an event.

Of course putting the computer and alternator in a faraday cage would be much better. But this might make a difference in an event.

I am sure some of our engineering level members can add to this.

Just an old guy wondering.
 

bw

Fringe Ranger
For the current political situation, Denial Of Service attacks or kinetic attacks on infrastructure seem much more likely than EMP. We should always be ready for the lights to go out (without the EMP pulse blowing circuits) and we should always be ready for the internet to go away indefinitely.

Additionally, the magnetic pole shift and weakening earth magnetic field has set us up for disastrous CMEs, and eventually one will get us. All should get versed on the various hypotheses about the pole shift - the CME danger, the various geophysical movements (which I consider mostly silly) and the micronova (which is quite plausible).

In all of that repertoire of risks, something sometime is going to take down enough worldwide grid/net/infrastructure to stop the movement of food. 95% of all people depend on food showing up in stores; 98% of Americans do; 100% of city dwellers do. Think about what happens when the food stops with no restart date.
 

LoupGarou

Ancient Fuzzball
It think there will be a major escalation of attacks against our infrastructure long before we see anything "explosively high tech" like EMP. HEMP is not going to be the threat, HPM-EMP via missile may be, depending on if more than just Israel, GB and US have them developed, usable and effective. The good news with the HPM-EMP attacks is their very small target area that they can effect per attack pulse. The bad news is that if one of the Cruise Missile HPM-EMP variants gets used, there can be 1000-2000+ pulses per programmed (or remotely piloted) "flight", so there could be quite a few small targets in a long string of targeted locations with just one of these Cruise Missiles. So, you would have to ask yourself if you live less than 1 quarter mile (half mile at best), from a "high value target"?
 

Tundra Gypsy

Veteran Member
I was in the grocery store; heading for the check out when the power went out. Suddenly it was very dark. Then I could see some light coming in the front of the store; glad I wasn't at the back of the store. It only lasted for about15 seconds, but it was quite a shock! It took a few minutes for the registers to come back online as well. It was a slow check out that day.

And because that happened out of nowhere; I'm now very aware of our electrical system and what could happen in an instant. I'm buying extra matches, keeping the gas tank topped off and going to keep a little extra cash on hand now.

It is one thing to be at home when the power goes out, but never at a store; it really shook me up.
 

Coco82919

Veteran Member
During a major storm, we had the power go out. We finished the surgery with back up power generator. Then about an hour later the back up power went out. We had to give discharge instructions with the light of our cell phones. It waa upsetting to everyone and memorable. The biggest lesson learned, was don't agree to have surgery or a procedure in severe conditions. Several patients had not picked up pain meds or other prescriptions ahead of time and all pharmacy closed during the storm. Something I never thought about until we were in the situation. In hind site I would have called in and not driven home in 70 to 90 mile a hour winds with whiteout conditions, driving 5 miles per hour. At times I could not see beyond my window. Some of our patients were stuck in their cars for 8 to 12 hours on the way home. We should have been closed, knowing the storm was coming, but conditions were good when we were supposed to report to work. All of us were stupid to come in, staff, doctors and patients.
So yes, things can change in a second.
 

Signwatcher

Has No Life - Lives on TB
I was in the grocery store; heading for the check out when the power went out. Suddenly it was very dark. Then I could see some light coming in the front of the store; glad I wasn't at the back of the store. It only lasted for about15 seconds, but it was quite a shock! It took a few minutes for the registers to come back online as well. It was a slow check out that day.

And because that happened out of nowhere; I'm now very aware of our electrical system and what could happen in an instant. I'm buying extra matches, keeping the gas tank topped off and going to keep a little extra cash on hand now.

It is one thing to be at home when the power goes out, but never at a store; it really shook me up.

I was a cashier many years ago before stores put in generators for backup. The power went out. We were tasked with emptying the store of customers by flashlight.

Stayed until we were dismissed.

One perk was from the produce department...they put a cart of veggies at the front and told employees to help themselves because it would be thrown out otherwise.
 

jed turtle

a brother in the Lord
I was in the grocery store; heading for the check out when the power went out. Suddenly it was very dark. Then I could see some light coming in the front of the store; glad I wasn't at the back of the store. It only lasted for about15 seconds, but it was quite a shock! It took a few minutes for the registers to come back online as well. It was a slow check out that day.

And because that happened out of nowhere; I'm now very aware of our electrical system and what could happen in an instant. I'm buying extra matches, keeping the gas tank topped off and going to keep a little extra cash on hand now.

It is one thing to be at home when the power goes out, but never at a store; it really shook me up.
A very important reminder for me. I always used to carry a small led flashlight in my pocket in case I got caught in a store during a loss of power. I had stopped that practice quite a while ago, so thanks for the reminder to start carrying again!
 

LoupGarou

Ancient Fuzzball
Considering the actual condition of our aging grids across CONUS, A physical attack in a few specific areas would do far more damage than any EMP could do, as would a well planned attack against the comms and SCADA parts of the electrical grids. HPM-EMP might be able to take a substation offline till they can replace all of the control gear. Or, if the enemy somehow got close enough to a power plant, cause the instrumentation and control gear to die a horrible death there, which may take a LONG while to fix depending on the number of spares they have offsite, or in the supply chain. If we are at war with china, and we don't have spares or any in the supply chain here, then it might be a VERY LONG time before it gets repaired.

I'm not going to go into details about what could be done to cause these issues, but the power grid is a well monitored and quickly controlled netowork of sensors as much as it is power distribution. And if those sensors go offline, or start feeding "bad" data, then a LOT of feedback loops will start acting on that. If other sensors are also dumping fake info, then the humans at the plants and networks may not intervene till a lot of damage becomes visible....
 

shane

Has No Life - Lives on TB
Our NukAlert was bought by DoD, but only after it was submitted to, and passed, the Navel Air Warfare Center for EMP survival testing.

With that process we also had a top DoD EMP expert visit our facilities here and I got to pick his brain regarding EMP likely effects.

Major takeaways…

Said any successful HEMP attack upon CONUS could only be done today by China, Russia or USA.

Said some cars that stopped via EMP would start again after 5 min or so left to sit.

Said cell phones would still work with any internal apps and memories, but of course not for calls as cell towers would be fried and no access to cloud or internet.

Said most every small electronics devices don’t require EMP cage protection IF not connected at the time to external grid power or recharging cord or external antenna.

Said if EMP metal can used, then need to also use metalized tape sealing seam, too.

Panic Early, Beat the Rush!
- Shane
 

BassMan

Veteran Member
Considering the actual condition of our aging grids across CONUS, A physical attack in a few specific areas would do far more damage than any EMP could do, as would a well planned attack against the comms and SCADA parts of the electrical grids. HPM-EMP might be able to take a substation offline till they can replace all of the control gear. Or, if the enemy somehow got close enough to a power plant, cause the instrumentation and control gear to die a horrible death there, which may take a LONG while to fix depending on the number of spares they have offsite, or in the supply chain. If we are at war with china, and we don't have spares or any in the supply chain here, then it might be a VERY LONG time before it gets repaired.

I'm not going to go into details about what could be done to cause these issues, but the power grid is a well monitored and quickly controlled netowork of sensors as much as it is power distribution. And if those sensors go offline, or start feeding "bad" data, then a LOT of feedback loops will start acting on that. If other sensors are also dumping fake info, then the humans at the plants and networks may not intervene till a lot of damage becomes visible....
Per another thread: "The name is Garou - LoupGarou." :cool:
 
Our NukAlert was bought by DoD, but only after it was submitted to, and passed, the Navel Air Warfare Center for EMP survival testing.

With that process we also had a top DoD EMP expert visit our facilities here and I got to pick his brain regarding EMP likely effects.

Major takeaways…

Said any successful HEMP attack upon CONUS could only be done today by China, Russia or USA.

Said some cars that stopped via EMP would start again after 5 min or so left to sit.

Said cell phones would still work with any internal apps and memories, but of course not for calls as cell towers would be fried and no access to cloud or internet.

Said most every small electronics devices don’t require EMP cage protection IF not connected at the time to external grid power or recharging cord or external antenna.

Said if EMP metal can used, then need to also use metalized tape sealing seam, too.

Panic Early, Beat the Rush!
- Shane
Is there a substitute for nukalert? Why did you stop making an amazing product?
Mine got misplaced during my niece was living here. I’m comforting knowing, if I do need it, it’ll let me know where to look.
 

West

Senior
EMP-Shield-SP-120-240-RL-02-2025-web.jpg
I just installed one of these for a customer..

Also one on her generator transfer box.

She also got two for her autos.
 

marsofold

Veteran Member
I have disconnected the 100 foot long wires from my solar panels going to the house inverter because of concerns over EMP, since my entire purpose for having solar is to have electricity after an apocalyptic event. Long wires collect more RF voltage than small gadgets. But I'm far from being near any target zone here in the middle of nowhere, WV. Seems better to me to err on the side of being paranoid about such possibilities, since I sincerely believe that America is the Mystery Babylon of Revelation doomed to overnight national destruction.
 

Thinwater

Firearms Manufacturer
Our NukAlert was bought by DoD, but only after it was submitted to, and passed, the Navel Air Warfare Center for EMP survival testing.

With that process we also had a top DoD EMP expert visit our facilities here and I got to pick his brain regarding EMP likely effects.

Major takeaways…

Said any successful HEMP attack upon CONUS could only be done today by China, Russia or USA.

Said some cars that stopped via EMP would start again after 5 min or so left to sit.

Said cell phones would still work with any internal apps and memories, but of course not for calls as cell towers would be fried and no access to cloud or internet.

Said most every small electronics devices don’t require EMP cage protection IF not connected at the time to external grid power or recharging cord or external antenna.

Said if EMP metal can used, then need to also use metalized tape sealing seam, too.

Panic Early, Beat the Rush!
- Shane
Exactly in line with what my late father told me. He was a PhD research who was hired by the DOE (Oakridge National lab) due to his work on high altitude nuke shots for his doctoral thesis. Good news for most cars and hand held electronics, not so much for the grid as a whole or computers plugged into it.
 

Chicken Mama

Veteran Member
Our NukAlert was bought by DoD, but only after it was submitted to, and passed, the Navel Air Warfare Center for EMP survival testing.

With that process we also had a top DoD EMP expert visit our facilities here and I got to pick his brain regarding EMP likely effects.

Major takeaways…

Said any successful HEMP attack upon CONUS could only be done today by China, Russia or USA.

Said some cars that stopped via EMP would start again after 5 min or so left to sit.

Said cell phones would still work with any internal apps and memories, but of course not for calls as cell towers would be fried and no access to cloud or internet.

Said most every small electronics devices don’t require EMP cage protection IF not connected at the time to external grid power or recharging cord or external antenna.

Said if EMP metal can used, then need to also use metalized tape sealing seam, too.

Panic Early, Beat the Rush!
- Shane
Tell us more, Shane. Spill it. Lol!
 

LoupGarou

Ancient Fuzzball
I'll be interested in Loup's view, but I'm guessing that $400 box has about $2 worth of lightning arrester in it.
The vehicle one is a stack of a few MOVs (Metal Oxide Varistors) in it that clamp at around 50 volts. The house one I have seen in two versions, an earlier model with 6 or 9 MOVs in it, or what seems to be a newer model with 6 Gas Discharge Tubes in it. Both have a clamping voltage in the upper 300 to 400 some volt range.

Someone did a teardown of the vehicle one and posted it:
https://www.reddit.com/r/Justrolledintotheshop/comments/12749g9 View: https://www.reddit.com/r/Justrolledintotheshop/comments/12749g9/emp_shield_opened/


Will it protect you from a HEMP attack? Might do something, but in reality not much in your house is going to be damaged by a HEMP pulse. Will it protect you from a HPM-EMP attack? Not a chance, only full shielding of each device as well as making sure that each device is FULLY unplugged will even begin to help.

If you really want to protect yourself from anything like lightning or serious surges, I would suggest either building your own (Digikey, Newark, and others sell the MOVs cheap, OR ordering a "BrickWall" unit for any specific device you want to protect.




As far as build your own, you want to use a stack of MOVs in parallel from hot to neutral, and a second stack from hot to ground, and a third stack from neutral to ground, and you want to buy them with a clamping limit of no less than 350 volts, and no more than 480 volts for a "120V" line. To do both sides of the split phase, you will need the three stacks for each split side, and not use a higher voltage stack between the two hot lines that make up the 240V run, you want to treat the two sides separately.

You can buy the gas discharge snubbers as well, but you will really need to buy extra component for that design as once the gas discharge triggers, it will short the capsule for a little while, and you will want fuses both in series with each snubber (or stack of snubbers in parallel to increase the amperage capability), as well as fast blow fuses in series with the power line coming into the snubber unit so that IF the gas discharge tubes shunt long enough it will pop the input fuses and disconnect the snubber (and the device that it is protecting from the surge and the heaving power line).

Again, nether of these will help with HPM-EMP, but will help with lighting and other lower frequency surges.

And if you are really worried about HEMP, you can buy the same protection that the military uses from Fischer Comms (Spikeguard series for example), Transtector, and/or PolyPhaser. Again, it's overkill, but if you want to you can buy them.
 

West

Senior
The vehicle one is a stack of a few MOVs (Metal Oxide Varistors) in it that clamp at around 50 volts. The house one I have seen in two versions, an earlier model with 6 or 9 MOVs in it, or what seems to be a newer model with 6 Gas Discharge Tubes in it. Both have a clamping voltage in the upper 300 to 400 some volt range.

Someone did a teardown of the vehicle one and posted it:
https://www.reddit.com/r/Justrolledintotheshop/comments/12749g9 View: https://www.reddit.com/r/Justrolledintotheshop/comments/12749g9/emp_shield_opened/


Will it protect you from a HEMP attack? Might do something, but in reality not much in your house is going to be damaged by a HEMP pulse. Will it protect you from a HPM-EMP attack? Not a chance, only full shielding of each device as well as making sure that each device is FULLY unplugged will even begin to help.

If you really want to protect yourself from anything like lightning or serious surges, I would suggest either building your own (Digikey, Newark, and others sell the MOVs cheap, OR ordering a "BrickWall" unit for any specific device you want to protect.




As far as build your own, you want to use a stack of MOVs in parallel from hot to neutral, and a second stack from hot to ground, and a third stack from neutral to ground, and you want to buy them with a clamping limit of no less than 350 volts, and no more than 480 volts for a "120V" line. To do both sides of the split phase, you will need the three stacks for each split side, and not use a higher voltage stack between the two hot lines that make up the 240V run, you want to treat the two sides separately.

You can buy the gas discharge snubbers as well, but you will really need to buy extra component for that design as once the gas discharge triggers, it will short the capsule for a little while, and you will want fuses both in series with each snubber (or stack of snubbers in parallel to increase the amperage capability), as well as fast blow fuses in series with the power line coming into the snubber unit so that IF the gas discharge tubes shunt long enough it will pop the input fuses and disconnect the snubber (and the device that it is protecting from the surge and the heaving power line).

Again, nether of these will help with HPM-EMP, but will help with lighting and other lower frequency surges.

And if you are really worried about HEMP, you can buy the same protection that the military uses from Fischer Comms (Spikeguard series for example), Transtector, and/or PolyPhaser. Again, it's overkill, but if you want to you can buy them.
How again I'll wish you was my naighbor!

There's no such thing in over kill in survival. Why I keep white vinegar and distilled water handy.

After kill, if its a gut shot, I immediately pull and wash the stew out of chest cavity. Then spray 50/50 white vinegar and distilled water into cavity and wipe clean!

All the best Loup!
:D
 

LoupGarou

Ancient Fuzzball
Is there a substitute for nukalert? Why did you stop making an amazing product?
Mine got misplaced during my niece was living here. I’m comforting knowing, if I do need it, it’ll let me know where to look.
A real substitute for it's ability to continuously monitor the radiation for over a decade on one battery? Not really. I have 3 of the NukAlerts and love them. I do have other devices, including what I would call the "runner up" in the capability, the Geiger2 from Mira Safety (which I have 2 of):

It's main plus is that is has a display, and enough processing power than it can track the radiation levels on a daily basis over a week or month. The main downside is that it runs on a built in Lithium Ion battery that needs to be recharged every few days to a week depending on how often you check the stats by hitting the button and turning on the display. There is a solar panel, that does help some, but it won't keep the unit charged. Good unit, more than twice the price of the NukAlert but as far as put one in your BoB and forget it like you can do with the NukAlert, you can't. Different device, different plan of use.


The other issue with the MIRA (and all other devices based on a Geiger tube) is swamping of the tube in where the level of incoming radiation is so high that the tube never gets a chance to reset (it does have a rather low "upper limit" to what it will handle). This means that with the MIRA (and similar units) you could be in a VERY dangerous area and the Geiger tube based devices would actually read very low levels. The NukAlert does not use a Geiger tube and does not have this issue.
 

LoupGarou

Ancient Fuzzball
I have disconnected the 100 foot long wires from my solar panels going to the house inverter because of concerns over EMP, since my entire purpose for having solar is to have electricity after an apocalyptic event. Long wires collect more RF voltage than small gadgets. But I'm far from being near any target zone here in the middle of nowhere, WV. Seems better to me to err on the side of being paranoid about such possibilities, since I sincerely believe that America is the Mystery Babylon of Revelation doomed to overnight national destruction.
If you are worried about the long lines, a set of stacks of MOVs that are rated for 150% of the maximum voltage the panel array flowing down the wires to your charge controller. For example, if you have a 90 volt max output, order at least 9 or 12 MOVs that start clamping at no less than 135V, preferably around 150V, a stack of 3 or 4 in parallel between the main positive and main negative line coming in, and another stack of 3-4 in parallel between the main positive and ground, and a third stack of 3-4 in parallel between the main negative and ground. Put this pack of MOVs between the power coming in from the panels, right at the charge controller, and after the input breakers or fuses that you should already have on that line coming in. This way if and when the MOVs ever clamp for whatever reason (I have them on my systems in case of lightning), they will pop the input fuses or trip the breakers to disconnect the line in and stop the flow.

I use these:
1775783376379.png

1775783411406.png

And yes, MOVs are good CHEAP protection. This one costs a whopping $6.06 for 25 of them. This gives you great protection (up to 6,000Amps pulse protection each device) and if you stack 24 of them into three stacks of 8 in parallel, you are effectively snubbing 48,000 Amp pulses and that should surely will pop the fuse or trip the breaker if the surge is long enough. Figure maybe $20-25 total with shipping and handling and it is very cheap insurance for your system.

I still would suggest having a spare charge controller on hand anyway since a LOT of things can happen that aren't surge caused. I keep stacks of spares of the important stuff for this reason.
 

summerthyme

Administrator
_______________
I've always got mine. Eating out with friends years ago when the power went out, no light in the restaurant. Held my flashlight over our heads with one hand and we continued with our dinner.
These days, almost everyone has a light...on their cellphone. I still carry a small, bright (and efficient LED) flashlight in my purse. Along with a small butane torch (not a lighter), my NukAlert, and a few basic meds. My jackknife goes into my pocket first thing in the morning.

Theres a bug-out-bag in the car (if we are both going somewhere further than 100 miles from home, there's two... both of us could still walk the 100 miles within 3 days).

I don't carry a bunch of water in the BOBs or vehicle. We usually have a quart bottle or two, but theres a Sawyer water filter in the BOB. We live in the Northeast... water is not a problem.

My Jackery is fully charged, as is the 12 volt LifePo battery. The latter is supposed to get connected to a solar panel and the LED lights for our storage containers this summer. They'd get repurposed (WTF, auto-corrupt?! It's never heard the word "repurposed" ...insisted it should be "reported") in a hurry if necessary. I also charged spare tablets, and put them in "airplane mode", and charged the various charging bricks. (I was shocked when I added them all up and realized there is an additional 120 amp hours of power just in that drawer)

It's Spring...I'm planting sufficient to supply both hubby and i, plus DS's family of five...just in case *something* happens that will prevent them from buying mostly fresh all next winter! Plus, I'm putting in enough storage/calorie crops (potatoes, beans, winter squash, root crops) that our entire extended family can survive if things go bad. If not, I'm sure local sales will be possible, or the soup kitchen will appreciate the donation.

We got the storage buildings cleaned, sorted, organized and labeled. Huge job...invaluable in how its made all the preps instantly accessible...but also if life bumbles on and our kids have to deal with the contents after we die.

I can now immediately put my hands on an oil lamp, a mirrored lamp shelf, and a bottle of lamp oil. Yes, it was handier on our home farm when we had at least one oil lamp sitting on a mirrored lamp shelf, with a box of "strike anywhere" matches velcroed to the underside of the shelf, but at least everything is together, and easily findable.

We have sufficient lye to make several hundred gallons of biodiesel, and there will be lard from the pigs currently heading to the woods pasture for the summer. Alternative feed stocks would be sunflower seeds (oil) or pumpkin seeds for oil.

I'm planning on growing a couple hundred oilseed sunflowers this year, for seed stock for a potentially necessary oilseed crop.

I stopped growing soybeans several years ago...I think I'd better find five or ten pounds of seed...open pollinated, which is gonna be tricky.

Soybeans can be a super valuable crop. It's a legumes, so puts nitrogen back into the soil. The beans are high in fat and protein...but like most beans, are loaded with anti-nutrients when eaten raw. Roasted whole soybeans are amazing nutrition. If you press the oil out, and feed the remaining solids (soybean meal), you've got a 45% protein source. Roasted whole beans...if you don't need the oil for fuel... are high in protein, fat and calories.

If we were still on our home farm, I would have filled up the 300 gallon diesel tank and 200 gallon gas tank. That would have covered us for 6 months, easily...close to 18 months with a strict rationing scenario. That doesn't happen here. The compensation is that all our sons are amazing creators...and they're all within an hour of the farm here. If things go bad for longer than a couple of weeks, I think we'll have multiple campers set up here. They all have some rural property, but we're the only ones with serious self sustaining infrastructure.

We've got 3, two years old steers to finish this Spring, 2 more for next Spring, and then three Waygu calves due in the next 3 weeks. If things went completely South, we'd keep a sow pig...but would have to find soneone with a boar by next Spring.

I need to top off a few supplies... bar and chain oil for the chainsaws, and vacuum pump oil (yes, we'll be milking by hand if the grid goes down. Until then, that little milker setup is worth its weight in gold!) I inventoried our salt supply, and decided to get an additional 4 plain blocks and at least 2 more that contain selenium. We are in an area where our soils lack sufficient selenium...if times change where we're not able to buy feed from out of the area, or we are able to grow all necessary calories, supplemental selenium is the difference between thriving livestock and dead offspring from white muscle disease.

I'm grateful to no longer be responsible for 50 high producing dairy cows, and an additional 70 head of young stock and beef cows. My vet medical inventory has become much more economical to maintain! DDIL insists on being pure organic (although does understand the requirement to use whatever is necessary to prevent suffering or death), but I can't keep myself from keeping a bunch of rapidly-going-out-of-date injectable vet meds...I shake them periodically, to resuspend solids. They're kept at 38°, in the dark. Various studies have said most of these particular meds were still perfectly efficacious after 15 years beyond the "expiration " dates.

Do I think its going to happen? No, not really. Do I think there is a non-zero chance of folks power going out for (at least) several weeks but NOT from weather? Oh, yeah...

Prepped enough that it mostly means a few minor tweaks.

Summerthyme
 

feralferret

Veteran Member
I have four LED lights on my person at all times when wearing my street clothes. One small flashlight, a penlight, a small keychain light, and another larger keychain light that also has a red laser pointer.

For many years I worked in buildings with no outside windows or skylights. You don't get much light through a foot thick concrete wall. On multiple occasions there was a power failure. At the time I had not yet added the keychain lights. When the power failed I would loan the small LED flashlight to a floor supervisor to lead the employees out to the rally point while I secured my area using the penlight and checked for stragglers. I always seemed to be the only employee with a flashlight and the only power failure lights were in the office areas.

The keychain light that also has a red laser pointer is a whopping $1.50 at Dollar Tree and can be valuable for signalling. I also have a couple of the $1.50 3 AA LED flashlights from there as backups to my aluminum Harbor Freight special that I carry in my pocket for if it dies.. The LED penlight stays in the tool pocket of my jeans and the extra small keychain light on my keyring which is attached to my belt mounted key ring fob.

The MOV based power line protectors proved their worth back when I was doing radio station engineering work. They made a big difference at a particularly lightning prone transmitter site. Much cheaper than replacing three phase 480 VAC to 240 VAC power transformers. The insurance company had said they would no longer pay for replacing the transformers if the surge protectors were not installed. They worked well. You do need to check and possibly replace them if they take a strike. MOVs are not indestructible.
 

LoupGarou

Ancient Fuzzball
...

The MOV based power line protectors proved their worth back when I was doing radio station engineering work. They made a big difference at a particularly lightning prone transmitter site. Much cheaper than replacing three phase 480 VAC to 240 VAC power transformers. The insurance company had said they would no longer pay for replacing the transformers if the surge protectors were not installed. They worked well. You do need to check and possibly replace them if they take a strike. MOVs are not indestructible.

Especially when your shack is connected to the grid, plus a 500-900 foot tall, ungrounded "lightning rod"...

Which is why I usually suggest putting them after the fuses or circuit breakers so that when they shunt, they cause the fuses or breakers to blow/trip and stop the surge from continuing. This usually keeps the MOVs from getting damaged, and definitely keeps the equipment from getting damaged. The problem is that now you have to replace the fuses or reset the breakers to get the equipment back running and online. For a few small devices at your home, or even the whole home that is one thing. For the transmitter shack out in a field at the edge of town, that means 20-30 minutes or more of the station being "down" and someone having to take a road trip out to the shack to flip the breakers or replace the fuses.
 
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