Ground rod help

[paulears]

Stop and think. That comment about huge expense is really worth googling and understanding.

With 3 phase distribution in the UK having 415V between phases, and houses being fed just one phase normally, the possibilities from disconnected Neutrals and grounds can be rough on the equipment and damn dangerous to people.

With the common systems nowadays bonding Neutral to ground at the point of entry, losing a ground isn't normall destructive in itself, but you have to think about when there are faults. If the ground is temporarily disconnected, then what if the neutral also gets disconnected somewhere between you and the local transformer? Here, we could have wild upswings on the voltage - and of course with the usual water pipes and other metalic structures at least attempting to provide a workable ground, the chance of shocks can be very worrying. The RSGB have all kinds of advice on grounding, but while a good RF ground can remove noise being carrried on the wiring ground, you now have multiple paths for fault currents. So if there is a mains ground fault, your antenna ground could see itself carrying hefty fault current down to the ground - though your RF equipments many ground components - as in feeders, sockets, the radios, and things like filters and other items. When we did not have regulations on this kind of thing, people generally did it, and I suspect that it never really did very much.

In the early days of broadcasting, studios would often have a mains ground, and a technical, clean ground, but this required the cases to be isolated from the electronics grounds and most equipment provided this, but then a few pieces of kit started bonding the electrical ground to the ground pin in the audio connectors and all sorts of hums and buzzes would start. You'd end up disconnecting things piece by piece till you found the culprit. Now separate technical grounds are rare - causing more grief than they ever reduced!

 

[Lauri-CoyoteFrostbite]

Kind'a creepy stuff, isn't it ?

If there is any good news here, its direct lightning strikes are very rare. And face it, if a bolt has your name on it there is bloody little you can do about it.
After all, that quad-zillion volt arc has probably travel several miles to select you out-- for what ever cosmological reasons, and no amount of ham ingenuity is going to save your bacon. Period !

I don't care what others may claim, there is no assurance that even the best, most professional mitigation efforts is 100% fool proof (more on that in a moment) against a direct hit. So forget that threat- have another beer and move on.

When I say move-on I mean protect yourself from the things protect-able--- the induced currents, surges and such from nearby strikes. That were the IEEE guide becomes relevant.
At my home with our radios I have tried to adhere to these guidelines.... but I live in the Rockies were anything metallic stuck in the air becomes a tantalizing object for lightning. We have a phenomenon here at the high altitudes called "St. Elmo's Fire, " the very close little sister to lightning.

Every woodstove flue is grounded-- "lightning rods" stud every structure-- but on still, quiet nights we will get these unearthly coronas dancing about the roof eves.
I made peace with these fairies long ago--- and today I just disconnect anything that doesn't need to be connected--- oh, and some times we leave these blithe spirits a plate of taco's, beer and a sprig of osha .


-----------------------------------------------------------------------------------------------------------------

After years of being around lightning, and developing deep respect for its awesome powers- I have also been amused at the almost sense of humour it can exhibit.

Years ago one of our remote sites in the Sandia Mountains, New Mexico-- went 'down.'
A crew went up to check it out--- I got a radio call ---

"Lauri, you have got to come up and see this !"


What I saw was amazing.
Apparently a lightning bolt had hit the 20 foot tower that held a small microwave dish. It must have course down the rigid heliax cable, entered the cinder block equipment hut and then exited. It exited thru the cinderblock wall cutting a perfect circular one foot hole. It blast'd thru to a propane tank used for auxillary power, hit the tank stripping off all its paint as if professionally sand blasted, and then it wielded the tank's mounting bolts fast to its concrete pad.
Inside the hut nothing was harmed. After resetting some circuit breakers everything was back in order.

Amazing stuff, Lightning.
The next really hairy thunderstorm you can try a peace offering of tacos .


Lauri



.

 

[RFI-EMI-GUY]

I have experienced an open neutral . It was after hurricane Andrew and the utility crew who restored my drop used the wrong crimp on the neutral. Some weeks later, some lights in the house very dim, and others way too bright. I shut it all down at once.

RE: PRCGuy's Comment about adjacent homes causing a 90VAC differential in ground rod potential has me reconsidering my irrigation system surge protection. I have new construction to my east and that home will be coming off of a completely different transformer feed . I am going to have to run a #6 and intermediate ground rods from the already bonded, SW corner of my house to the SE corner (garage) . When all is said and done, I might as well go completely around. I have no crawl space to run a dedicated bonding conductor.

 

[RFI-EMI-GUY]

Kind'a creepy stuff, isn't it ?

If there is any good news here, its direct lightning strikes are very rare. And face it, if a bolt has your name on it there is bloody little you can do about it.
After all, that quad-zillion volt arc has probably travel several miles to select you out-- for what ever cosmological reasons, and no amount of ham ingenuity is going to save your bacon. Period !

I don't care what others may claim, there is no assurance that even the best, most professional mitigation efforts is 100% fool proof (more on that in a moment) against a direct hit. So forget that threat- have another beer and move on.

When I say move-on I mean protect yourself from the things protect-able--- the induced currents, surges and such from nearby strikes. That were the IEEE guide becomes relevant.
At my home with our radios I have tried to adhere to these guidelines.... but I live in the Rockies were anything metallic stuck in the air becomes a tantalizing object for lightning. We have a phenomenon here at the high altitudes called "St. Elmo's Fire, " the very close little sister to lightning.

Every woodstove flue is grounded-- "lightning rods" stud every structure-- but on still, quiet nights we will get these unearthly coronas dancing about the roof eves.
I made peace with these fairies long ago--- and today I just disconnect anything that doesn't need to be connected--- oh, and some times we leave these blithe spirits a plate of taco's, beer and a sprig of osha .

After years of being around lightning, and developing deep respect for its awesome powers- I have also been amused at the almost sense of humour it can exhibit.

Years ago one of our remote sites in the Sandia Mountains, New Mexico-- went 'down.'
A crew went up to check it out--- I got a radio call ---

"Lauri, you have got to come up and see this !"


What I saw was amazing.
Apparently a lightning bolt had hit the 20 foot tower that held a small microwave dish. It must have course down the rigid heliax cable, entered the cinder block equipment hut and then exited. It exited thru the cinderblock wall cutting a perfect circular one foot hole. It blast'd thru to a propane tank used for auxillary power, hit the tank stripping off all its paint as if professionally sand blasted, and then it wielded the tank's mounting bolts fast to its concrete pad.
Inside the hut nothing was harmed. After resetting some circuit breakers everything was back in order.

Amazing stuff, Lightning.
The next really hairy thunderstorm you can try a peace offering of tacos .


Lauri

View attachment 124175

.

Adhering to Motorola R56 (Or Abiding per "The Dude") is pretty close to foolproof. We had an R56 site in Pensacola that got along pretty well for a number of years and then suddenly stuff was blowing up. We had some folks out, recommending all kinds of protective devices like RS232 surge protectors for the trunking control equipment . Never mind that none of that was needed before. (each cabinet already bonded to each other cabinet) Then after a bit of investigation into when damage started happening, it turned out a contractor had been on site installing fiber to the site and had trenched through the buried ground ring in a couple places. This bit of deviation from R56 created havoc.

 

[Lauri-CoyoteFrostbite]

"........................I might pour some flasks of mercury around my ground rods. Good Idea? ....................."

Oh Sweet Mary !.... No !!

For one thing, if any 'authorities' caught wind you were pouring metallic mercury into the ground they would be all over you faster than flies on stink !

Another thing... Mercury is quite expensive to be using like that, but those two reasons aside, its unlikely it would remain any where about the ground rods for long..... it is super heavy and would quickly seek a stable geologic strata.... dissapearing into god-knows what.... your water aquifer ? In Florida that would not take long.

I remember talks with olde-thyme AM radio broadcast engineers. They told me about attempts to improve their station grounds- hence their signals- by 'salting' the ground about their towers. They would use "blue stone"-- copper sulfate crystals. It would work.... for awhile, but then leach out and the effects would dissapear. Plus it was quite poisonous to cattle etc.
I doubt its done any more.

I have some wells with metal casings that go down deep. One is close to the house and is--of course- tied into my ground system. I'd elect a deep well casing over mercury else any day .

Lauri


.

 

[AJAT]

I will add, NEVER disconnect the existing main utility ground rod, not even for a moment. If you need to attach another wire use a second bronze clamp to the existing rod or to the existing bare wire.

We had a tech here disconnect that ground rod "to measure ground resistance" and it caused $250K in equipment damage. The utility ground rod is there not only for lightning protection, it is for safety and balancing the neutral.

There are proper ways to measure ground resistance and lifting a live utility ground is not one of them.

I second that. I was working as an electrician renovating a house. We upgraded the electrical service. The person who installed the ground rod did not tighten the ground wire. It came loose. All the lights got real bright, power saws started turning really fast, and all the hard wired smoke detectors smoked and shot out flames. Basically it sent 220v volts through the house. Not a good day.

 

[RFI-EMI-GUY]

"........................I might pour some flasks of mercury around my ground rods. Good Idea? ....................."

Oh Sweet Mary !.... No !!

For one thing, if any 'authorities' caught wind you were pouring metallic mercury into the ground they would be all over you faster than flies on stink !

Another thing... Mercury is quite expensive to be using like that, but those two reasons aside, its unlikely it would remain any where about the ground rods for long..... it is super heavy and would quickly seek a stable geologic strata.... dissapearing into god-knows what.... your water aquifer ? In Florida that would not take long.

I remember talks with olde-thyme AM radio broadcast engineers. They told me about attempts to improve their station grounds- hence their signals- by 'salting' the ground about their towers. They would use "blue stone"-- copper sulfate crystals. It would work.... for awhile, but then leach out and the effects would dissapear. Plus it was quite poisonous to cattle etc.
I doubt its done any more.

I have some wells with metal casings that go down deep. One is close to the house and is--of course- tied into my ground system. I'd elect a deep well casing over mercury else any day .

Lauri


.

Ok I will keep the mercury where it belongs, in my molars....!!!

 

[Zigzag03]

You should have a surge protector at the entry point to the house which is grounded via a ground rod. It is best to use the existing ground rod located at your electrical meter so that any lightning does not travel through your interior wiring as would happen by simply grounding to an electrical box/outlet.

If that location is not convenient, you can add a new ground rod for the surge protector, but it must be bonded to the existing one with #6 solid copper wire. For every 16 feet of distance between the ground rods, an additional ground rod bust be placed. For example a surge protector around corner of house 32 or 48 feet away.

Existing ground 8 foot rod> |-------------|*------------- | <New 8 foot ground rod 32 feet away.
Existing ground 8 foot rod> |-------------|*------------- |*------------- | <New 8 foot ground rod 48 feet away.

|* midpoint 8 ft ground rod.
| 8 ft ground rod.
------------- #6 solid copper wire, ~16 feet long.

Am getting my ground rods driven, one every 16". Now around a corner, should the rod be 16' on the diagonal, or must I measure around the right angle. As it stands, I'm about 17' around the corner on the diagonal, would a change to #4 copper make up for the slight difference in spacing? I guess I'm asking, code not withstanding, how precise must the spacing be to actually do the job? Thanks for everyones' help and input.

 

[MUTNAV]

"........................I might pour some flasks of mercury around my ground rods. Good Idea? ....................."

Oh Sweet Mary !.... No !!

For one thing, if any 'authorities' caught wind you were pouring metallic mercury into the ground they would be all over you faster than flies on stink !

Another thing... Mercury is quite expensive to be using like that, but those two reasons aside, its unlikely it would remain any where about the ground rods for long..... it is super heavy and would quickly seek a stable geologic strata.... dissapearing into god-knows what.... your water aquifer ? In Florida that would not take long.

I remember talks with olde-thyme AM radio broadcast engineers. They told me about attempts to improve their station grounds- hence their signals- by 'salting' the ground about their towers. They would use "blue stone"-- copper sulfate crystals. It would work.... for awhile, but then leach out and the effects would dissapear. Plus it was quite poisonous to cattle etc.
I doubt its done any more.

I have some wells with metal casings that go down deep. One is close to the house and is--of course- tied into my ground system. I'd elect a deep well casing over mercury else any day .

Lauri


.

Actually its still an option, but everyone I knew would just have improved the ground system.

From the grounding bonding shielding handbook in (mil-hdbk 419a) 1987

2.9.3 Chemical Salting. Reduction of the resistance of an electrode may also be accomplished by the addition
of ion-producing chemicals to the soil immediately surrounding the electrode. The better known chemicals in
the order of preference are:
a. Magnesium sulphate (MgS04) - epsom salts.
b. Copper sulphate (CuS04) - blue vitriol.
c. Calcium chloride (CaC12).
d. Sodium chloride (NaCl) - common salt.
e. Potassium nitrate (KNO3) - saltpeter.
Magnesium sulphate (epsom salts), which is the most common material used, combines low cost with high
electrical conductivity and low corrosive effects on a ground electrode or plate. The use of common salt or
saltpeter is not recommended as either will require that greater care be given to the protection against
corrosion. Additionally, metal objects nearby but not related to grounding will also have to be treated to
prevent damage by corrosion. Therefore, salt or saltpeter should only be used where absolutely necessary.



Thanks
Joel

 

[MUTNAV]

Yeah, I did not trust my main rod at this 1986 house and simply drove another and bridged the two. I have one side and part of the rear with #6 bonded around the corner with intermediary rods.

Coincidentally, today I bought another ground rod and am installing it at my garage to protect my RainBird irrigation timer which blew up on April 15th.

Lightning struck a tree and metal fence post near my "grounded" side of the house, traveled into the irrigation PVC pipes and 8 control wires and caused damage 60 feet away to the timer in the far side of house, garage , blew apart the timer box, and put a surge into the branch service for the garage and caused some other damage.

The next surge like this will pass through the protector I am building which has MOV's , fuses and finally spark gaps to ground. Nobody makes one of these off the shelf. Thankfully I have a well equipped surplus house in town for heavy duty phenolic, AGC fuse blocks and DigiKey for the rest.

Your attention to this is really admirable.

BTW Metal fences get their own horizontal ground wire for their length...

If I ever get my own "forever home" I'll try and do as well as you with grounding, in the mean time, don't forget to put the MOV's in a strong case... When the explode, they can do so with a lot of force. In some of my equipment they were in a small metal box at the power feed, which was convienient to contain the mess they made.

Thanks
Joel

 

[MUTNAV]

Kind'a creepy stuff, isn't it ?

If there is any good news here, its direct lightning strikes are very rare. And face it, if a bolt has your name on it there is bloody little you can do about it.
After all, that quad-zillion volt arc has probably travel several miles to select you out-- for what ever cosmological reasons, and no amount of ham ingenuity is going to save your bacon. Period !

I don't care what others may claim, there is no assurance that even the best, most professional mitigation efforts is 100% fool proof (more on that in a moment) against a direct hit. So forget that threat- have another beer and move on.

When I say move-on I mean protect yourself from the things protect-able--- the induced currents, surges and such from nearby strikes. That were the IEEE guide becomes relevant.
At my home with our radios I have tried to adhere to these guidelines.... but I live in the Rockies were anything metallic stuck in the air becomes a tantalizing object for lightning. We have a phenomenon here at the high altitudes called "St. Elmo's Fire, " the very close little sister to lightning.

Every woodstove flue is grounded-- "lightning rods" stud every structure-- but on still, quiet nights we will get these unearthly coronas dancing about the roof eves.
I made peace with these fairies long ago--- and today I just disconnect anything that doesn't need to be connected--- oh, and some times we leave these blithe spirits a plate of taco's, beer and a sprig of osha .View attachment 124176


-----------------------------------------------------------------------------------------------------------------

After years of being around lightning, and developing deep respect for its awesome powers- I have also been amused at the almost sense of humour it can exhibit.

Years ago one of our remote sites in the Sandia Mountains, New Mexico-- went 'down.'
A crew went up to check it out--- I got a radio call ---

"Lauri, you have got to come up and see this !"


What I saw was amazing.
Apparently a lightning bolt had hit the 20 foot tower that held a small microwave dish. It must have course down the rigid heliax cable, entered the cinder block equipment hut and then exited. It exited thru the cinderblock wall cutting a perfect circular one foot hole. It blast'd thru to a propane tank used for auxillary power, hit the tank stripping off all its paint as if professionally sand blasted, and then it wielded the tank's mounting bolts fast to its concrete pad.
Inside the hut nothing was harmed. After resetting some circuit breakers everything was back in order.

Amazing stuff, Lightning.
The next really hairy thunderstorm you can try a peace offering of tacos .


Lauri

View attachment 124175

.

I was going to ask you about St Elmos fire, you said you do SOTA (Summits on the air ) occasionally, and I was wondering how you deal with it... I've heard that at some locations, just raising a mitten above your head will attract a lot of static, what to do about antennas ! ! ! (except get to a lower location)

Thanks
Joel

 

[Zigzag03]

To expand on my question just above, is the 16' spacing of the rods the critical factor, or should it be the wire I'm concerned about? I will need to run the wire up and over several concrete pads and walks, and so even if the rods are spaced as indicated, the wire runs in some cases will be much longer than 16'. Is this going to cut it?

Edit... Good exercise, btw!!

 

[prcguy]

From what I've read the recommended spacing between ground rods is roughly twice their length making it 16ft between 8ft long rods. Closer spacing looses effectiveness and a little further apart should not be a problem. You could also go with 10ft long rods making the spacing 20ft between rods.

I would also upsize the wire if you can afford it. NEC requires at least 6ga wire but at my old work place the 125ft X 225ft building originally had 75 ground rods around the perimeter about 4ft out from the building foundation and the tops of the rods were buried about 4ft underground. The interconnecting wire was bare stranded copper 500MCM and cadwelded at each rod. Over the years installing additional antennas we probably added more than 100 ground rods and all wiring was 500MCM.

To expand on my question just above, is the 16' spacing of the rods the critical factor, or should it be the wire I'm concerned about? I will need to run the wire up and over several concrete pads and walks, and so even if the rods are spaced as indicated, the wire runs in some cases will be much longer than 16'. Is this going to cut it?

Edit... Good exercise, btw!!

 

[RFI-EMI-GUY]

Am getting my ground rods driven, one every 16". Now around a corner, should the rod be 16' on the diagonal, or must I measure around the right angle. As it stands, I'm about 17' around the corner on the diagonal, would a change to #4 copper make up for the slight difference in spacing? I guess I'm asking, code not withstanding, how precise must the spacing be to actually do the job? Thanks for everyones' help and input.

I have the same situation with corners. I plan to try and maintain the 16 feet on the diagonal, even if the wire between exceeds 16 feet . It is the rod spacing that is important. I think you will be fine with #6 as long as it has contact with the soil. I might dig out R56 specs to see if this is specifically addressed.

 

[RFI-EMI-GUY]

Your attention to this is really admirable.

BTW Metal fences get their own horizontal ground wire for their length...

If I ever get my own "forever home" I'll try and do as well as you with grounding, in the mean time, don't forget to put the MOV's in a strong case... When the explode, they can do so with a lot of force. In some of my equipment they were in a small metal box at the power feed, which was convienient to contain the mess they made.

Thanks
Joel

I completed the surge protector a few days ago and it looks pretty good. The case is one of those flame proof thermoplastic boxes for electrical wiring. Yes, the explosive potential was considered. I don't want a bomb so the cover, rather than using the sturdy steel screws provided, is going to be attached with "frangible" nylon nuts on studs. The nuts are common nylon ones that I intend to scribe with an abrasive disk . I don't have the budget or equipment to test this, but I expect that the debris will be glass fuses rather than MOV s as the first line of protection is a fuse for each circuit, followed by a spark gap. Hopefully my efforts in this will remain untested.

 

[RFI-EMI-GUY]

To expand on my question just above, is the 16' spacing of the rods the critical factor, or should it be the wire I'm concerned about? I will need to run the wire up and over several concrete pads and walks, and so even if the rods are spaced as indicated, the wire runs in some cases will be much longer than 16'. Is this going to cut it?

Edit... Good exercise, btw!!

As far as concrete pads. It would be great to go under them or around them, but that is not always possible. In my case, to complete the ring, I will have to go past the driveway and a sidewalk. The expansion joint is the only way for the driveway. The sidewalk, I may be able to drive under the sandy soil. I also have a pool deck and have not decided whether to go around it or pass through the channel drain seperating the pool from the house. I really should spend the money and go around the pool entirely.

My philosophy is that the grounding systems for homes are entirely inadequate for modern electronics and anything I can do to improve the bonding and equalization of ground potential for the systems inside is worth the effort even if some compromises have to be made. Here in Florida we have no requirement for "lightning rods", aka air terminals, for single family residences. I have a metal chimney cap extending far above the roof that appears to have been struck, also metal flashing, fan vents and gutters. Our fire code does not address this, yet there are attic fires. I intend to ground those at some point as well.

 

[RFI-EMI-GUY]

Actually its still an option, but everyone I knew would just have improved the ground system.

From the grounding bonding shielding handbook in (mil-hdbk 419a) 1987

2.9.3 Chemical Salting. Reduction of the resistance of an electrode may also be accomplished by the addition
of ion-producing chemicals to the soil immediately surrounding the electrode. The better known chemicals in
the order of preference are:
a. Magnesium sulphate (MgS04) - epsom salts.
b. Copper sulphate (CuS04) - blue vitriol.
c. Calcium chloride (CaC12).
d. Sodium chloride (NaCl) - common salt.
e. Potassium nitrate (KNO3) - saltpeter.
Magnesium sulphate (epsom salts), which is the most common material used, combines low cost with high
electrical conductivity and low corrosive effects on a ground electrode or plate. The use of common salt or
saltpeter is not recommended as either will require that greater care be given to the protection against
corrosion. Additionally, metal objects nearby but not related to grounding will also have to be treated to
prevent damage by corrosion. Therefore, salt or saltpeter should only be used where absolutely necessary.



Thanks
Joel

I was just joking about the mercury, CF s reaction was expected! Epsom salts are pretty cheap. I have not measured ground conductivity here but since this was once seabed and later agricultural, I expect a lot of salinity.

 

[MUTNAV]

I completed the surge protector a few days ago and it looks pretty good. The case is one of those flame proof thermoplastic boxes for electrical wiring. Yes, the explosive potential was considered. I don't want a bomb so the cover, rather than using the sturdy steel screws provided, is going to be attached with "frangible" nylon nuts on studs. The nuts are common nylon ones that I intend to scribe with an abrasive disk . I don't have the budget or equipment to test this, but I expect that the debris will be glass fuses rather than MOV s as the first line of protection is a fuse for each circuit, followed by a spark gap. Hopefully my efforts in this will remain untested.

When the ones on my equipment blew up, it was the MOVs', it looked more like a small firecracker had gone off, had to use a vacuum to remove the debris (fortunately everything is plastic since it had to be done with power on). It wouldn't have damaged anything, but the clean up would have been more difficult if they hadn't been contained. In normal use the MOV shouldn't blow up at all, ours did since at some point a tower was moved away from a shelter and the lightning protection that the tower provided wasn't considered, so the shelter took a hit. The failure mode meant that it wasn't even noticed until it was decided to do a good cleaning on the equipment.

We didn't have fuses/circuit breakers until the power got to individual cabinets (aside from the power entry panel). Just a power filter and the MOV's.

Thanks
Joel

 

[MUTNAV]

As far as concrete pads. It would be great to go under them or around them, but that is not always possible. In my case, to complete the ring, I will have to go past the driveway and a sidewalk. The expansion joint is the only way for the driveway. The sidewalk, I may be able to drive under the sandy soil. I also have a pool deck and have not decided whether to go around it or pass through the channel drain seperating the pool from the house. I really should spend the money and go around the pool entirely.

My philosophy is that the grounding systems for homes are entirely inadequate for modern electronics and anything I can do to improve the bonding and equalization of ground potential for the systems inside is worth the effort even if some compromises have to be made. Here in Florida we have no requirement for "lightning rods", aka air terminals, for single family residences. I have a metal chimney cap extending far above the roof that appears to have been struck, also metal flashing, fan vents and gutters. Our fire code does not address this, yet there are attic fires. I intend to ground those at some point as well.

I had to wonder about the fire code for awhile, and its application to homes... The part I'm wondering about is when electric utilities move from poles to underground, if the loss of any lightning protection provided by utility poles needs to be readdressed.

Thanks for making me think about it, ....

Joel

 

[RFI-EMI-GUY]

When the ones on my equipment blew up, it was the MOVs', it looked more like a small firecracker had gone off, had to use a vacuum to remove the debris (fortunately everything is plastic since it had to be done with power on). It wouldn't have damaged anything, but the clean up would have been more difficult if they hadn't been contained. In normal use the MOV shouldn't blow up at all, ours did since at some point a tower was moved away from a shelter and the lightning protection that the tower provided wasn't considered, so the shelter took a hit. The failure mode meant that it wasn't even noticed until it was decided to do a good cleaning on the equipment.

We didn't have fuses/circuit breakers until the power got to individual cabinets (aside from the power entry panel). Just a power filter and the MOV's.

Thanks
Joel

I blew up some MOV's with a very reactive circuit I built. The MOV's were to protect my home while I experimented in the garage.

Basically I had a variac running a stepdown transformer of 60VAC and powering a magnetic coil I wound. The coil was levitating over a 3/4 inch aluminum plate using eddy currents.