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Shack Surge Protection

from Mike Higgins, K6AER on December 26, 2017
View comments about this article!

Shack Surge Protection
By Mike Higgins, K6AER


Surge protection of the home and especially the ham shack gear, is always something we will get around to… maybe next month. Then one night on the way home you see the flash of lightning. In my case, I have just moved into a new location and it was on my “to-do” list. At that moment, I saw the bolt of lightning hit the top HV wires (7200 volt) on the utility pole, then neighborhood went dark.

I pulled into the driveway, just in time, to see my wife leaving the house. She doesn’t do dark. I started the generator and feed the power into the home main panel and the house was livable again. Wife went back into the house. Everything looked to be working…. until I got to the ham shack. I was optimistic about my luck until I got to the amplifier. It came up with plenty of fault codes but that was all. The amplifier was not going to be a part of the ham station in the near future. I had not had time to do a proper surge protection on the old home due to cotton wiring and some other grounding issues plus installing a new distribution panel. Now I have time.


The amplifier was under warranty and a few days later I sent it off for repair. Time to put a surge protector in place. Nothing like closing the barn doors after the cattle escape. Most surge protectors available on the market, install at the main feed panel. The surge protector hot lines are connected via breakers to each side of the split phase feed to the home. The protector hot line needs either fused or circuit breakers because sometimes they short with a large surge event. A typical surge protector has a red and black wire for each 120-volt AC side. These hot wires are connected to a 20-50 amp breaker. The white and green wires connect to the panel master ground. The surge protector seeing a high voltage event will conduct to ground at about 200 volts on each side of the 120 vollt connections. This limits the much higher voltages from going down Stream.

The Device

Normally surge protectors mount at the Main AC panel for best results. In my case I decided to build the unit for remote placement at my upstairs ham shack. I had decided to feed the ham shack from a dedicated 240-volt/30 amp feed, from the main panel. The surge protector is placed between the AC feed and the equipment. Besides the surge protection, the panel protection unit has a shut off switch for the split phase feed and AC fuses for each side of the 240-volt feeds. The AC disconnect switch is very Important for it disconnects the station from the grid when not on the air. I selected the EATON type 2 SPD (surge protection device) for the main portion of the unit for several reasons. It will handle 36000 amps of surge and comes with a $25,000 insurance policy. For $69.00 how can you lose? It is listed under part number CHSPT2SURGE. The attachment fitting is a ½ inch pipe thread with the 4 wires coming out. Leads are about 12 inches long. The disconnect box is a 30 amp unit by Square D with internal screw in fuse connections and a SPST Disrupter Switch, Lowes item number 92606. These disrupter boxes are under $20 in cost. I use 20 amp fuses in mine.

My shack surge protection assembly is assembled as an outboard unit and plugged into the wall receptacle feed with a 40 amp dryer plug. Wiring is direct connection with the leads soldered and coated with JB OxyGard paste to prevent connection corrosion. Make sure the connections are very tight.

The surge protection unit has two LED’s that glow green when all is OK. If the unit has been compromised the LED’s will not glow. Normal surges have a time span of under 20 uS. This is how you can have 36,000 amps of surge protection with a 12-gage wire.

It is important to have a very low impedance ground with any surge protection device. The unit I have shown has the ground and common safety ground connected by the feed cable but the unit also has a separate ground chassis connection via a brass ¼ 20 stud on the chasses. Make sure you remove the paint from the stud mounting area for a good electrical connection. All station grounds must be at a common feed point to keep surge potential at the same voltage. If you use the stud ground, on the box assembly, use at least a number 6 stranded cable for the ground connection back to the main panel.

Shown below is the diagram of the electrical connections. The plate to cover the 120-volt receptacle and the 240-volt receptacle was custom made from a receptacle/switch plate with the liberal application of a metal half round file to make the hole for the 240-volt receptacle. Nice way to spend 30 minutes. When connecting the 120-volt plug feeds to the surge protector make sure the two lines are balanced in the loads. This will keep the two 120-volt feeds at the same voltage potential.

The interrupter box can take up to a 30 amp, screw in fuses and disconnects both 120 VAC lines from the station.

The AC disconnect switch was obtained from LOWES along with the other electrical parts. I prefer AC fuses to circuit breakers in this application for I believe AC fuses to be quicker in a massive short scenario. The whole project can be done under three hours not including the AC feed to the shack. The beauty of this system is not only will your equipment be protected but you can remove the shack equipment from the AC mains with the disconnect switch. This adds an extra margin of comfort when you see Mother Nature kicking up her heals.

Just a note about MOV surge protectors. If you have many small surges or a large one, the MOV’s will degrade over time or go to a direct short. In the case of very high current, the MOV’s can briefly catch fire due to a direct short. As a result, most commercial surge protectors are filled with sand. Therefore, they are heavy for their size. Surge protected plug strips do not do this and as a result can catch fire in a short condition.

Depicted below is the wiring diagram of the portable surge protector assembly. All the parts came from Lowes electrical department. Receptacle part numbers are on the diagram. Total project cost was under $120.

May the Joules be with you.

Member Comments:
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Shack Surge Protection  
by KK6HUY on December 26, 2017 Mail this to a friend!
Thank you. Good post. Timely as well.
RE: Shack Surge Protection  
by N8FVJ on December 26, 2017 Mail this to a friend!
The GE GMOV over time drifts lower than the advertised operating voltage. 130 volt rated GMOVs did fail 10-15 years after installation. So, newer users specified 140 volt GMOVs in their equipment. It has been over 30 years now (I believe) and not sure if the newer 140 volt GMOVs have failed at the 120-125 volt AC mains voltage.
Shack Surge Protection  
by K0RO on December 26, 2017 Mail this to a friend!
Great article. I checked Amazon and local Lowes and parts are readily available. Price favors Lowes. It will be my next project.
RE: Shack Surge Protection  
by AA4PB on December 26, 2017 Mail this to a friend!
According to the National Electric Code (NEC), the only place that the neutral (white) and ground (green) should be connected together is in the main electrical panel. They should NOT be tied together in your remote box.
RE: Shack Surge Protection  
by K6AER on December 26, 2017 Mail this to a friend!
Very hard to do with a three wire dryer plug. The second ground is a redundant safety ground. Unless you set up the remote in the ham shack as a full breaker panel you have to do what I did.

Many older home have no provision for the second safety ground. My house in Michigan was old enough it did not have a safety ground at all.
Shack Surge Protection  
by K0IC on December 26, 2017 Mail this to a friend!
I think 20-foot ground rods would help. If the ground is rocky, one might need salt, a water source, and a horizontal ground.
RE: Shack Surge Protection  
by K2JVI on December 27, 2017 Mail this to a friend!
As someone who used to do commercial/industrial low voltage systems, I second the comments regarding the neutrals tied to ground, separate these. Additionally regarding the comments on the 20' ground rods-a person can install numerous 10' ground rods and be very effective, HOWEVER care MUST be taken to space them properly so that each ground rod's "sphere of influence" doesn't overlap which would reduce the effectiveness of the grounding. A good "rule of thumb" would be to space 10' ground rods at least 16-20 feet apart. And last but certainly not least,and per NEC and BICSI standards, all grounding networks shall be bonded to the main electrical ground, this to maintain "equipotential" across the entire grounding network. It's entirely possible to have large potential differences between two ground networks that are not bonded together.
RE: Shack Surge Protection  
by K2JVI on December 27, 2017 Mail this to a friend!
I noticed a four-pronged dryer cord in the main picture and your schematic shows four wires ( 2 hots, neutral, and ground) feeding your switch/suppressor. What one could do is feed the shack with either 10/3 or 8/3 with ground. (black,red,white,bare). At the main panel, the neutral(white) and the ground(bare) can connect at the main neutral bus bar,or the ground could connect to the metal panel case. This would allow for the neutral and ground to be separated at the suppressor disconnect. Hey just my .02
RE: Shack Surge Protection  
by K6AER on December 27, 2017 Mail this to a friend!
The plug is a 4 wire 30 amp. type but the feed to the shack is 3 wire. I build the surge protector for future shack use. In the process of moving back out West where I have a separate hams shack building. It will be to NEC code.
RE: Shack Surge Protection  
by K6AER on December 27, 2017 Mail this to a friend!
The plug is a 4 wire 30 amp. type but the feed to the shack is 3 wire. I build the surge protector for future shack use. In the process of moving back out West where I have a separate hams shack building. It will be to NEC code.
RE: Shack Surge Protection  
by KE7FD on December 27, 2017 Mail this to a friend!
Very good timing. I'm rebuilding my shack and actually bought a master kill switch for my radio gear line and can easily incorporate the MOV's since I have yet to implement that part of the project. The flexible nature of this addition should allow it to be used in a lot of shacks. Since comments have been made about MOV failure over time, I'll likely purchase multiple sets to replace on a regular basis (5 - 10 years?). It'll be easy to do by killing the power at the switch, and swap out the MOV bank.

Thanks again!

Glen - KE7FD
RE: Shack Surge Protection  
by K2JVI on December 27, 2017 Mail this to a friend!
RE-Four prong plug-gotcha-good plan. About 15 years ago we did a major re-model to our house complete with new 200 amp panel etc. I have a dedicated 20 amp 120 volt circuit and a dedicated 20 amp 240 volt circuit for the ham shack,with lighting on a separate circuit. Also as you can imagine based on a previous post, I have an extensive grounding network with a #2 solid copper coming in to the shack for grounding(use split-bolts for connections).
Shack Surge Protection  
by W4CNG on December 28, 2017 Mail this to a friend!
I have a whole house surge protection on the main 200A distribution panel. The shack is fed with one 20A and one 30A 120VAC feeds. The single 20A feeds a 1500VA UPS with two Group 27 batteries (it is a 24VDC UPS). The UPS feeds all radio's and computers. The 30A circuit feeds the Ameritron Linear amplifier. I had the same system in my former home for 15 years and it worked like a champ. The only issue is that after 4 years or so the batteries need replacing since they sit on line most of the time. The system will run everything (except the Linear) for 12-16 hours depending on how much I would operate. Nice article with good explanation for how and why.
RE: Shack Surge Protection  
by K9MHZ on December 28, 2017 Mail this to a friend!
"According to the National Electric Code (NEC), the only place that the neutral (white) and ground (green) should be connected together is in the main electrical panel. They should NOT be tied together in your remote box."

^^^^ This!^^^^

Don't know why you're tying them together on your metal box. If the green lifts, you've got AC on your box metal.
Shack Surge Protection  
by AC5WO on December 28, 2017 Mail this to a friend!
For surge protection, the energy that passes through is more important than the maximum surge that the surge protection device can handle without damage to the surge protector. I prefer series circuits like the big honking low pass filters from Zero Surge.
They work by passing the 60 Hz power while reflecting the higher frequency content of surges/transients on the power line.

The other big concept of surge protection is to focus on tying equipment together to a common ground using short, fat conductors. The goal is to make all grounds rise and fall in voltage together to minimize the voltage differences to a level that doesn't cause damage. This is much more important than long ground rods, especially when the wire to the ground rod is 10s of feet long. Treat surge protection like the RF circuit that it is.
RE: Shack Surge Protection  
by AA4PB on December 28, 2017 Mail this to a friend!
The problem with connecting ground and neutral together at any point other than the main entrance breaker panel is that now you have load current that should flow in the neutral only, flowing in the grounding wire as well. This means that all points in the safety grounding circuit are no longer at at the same voltage, depending on how the neutral currents divide. The grounding conductors should have no current flowing in them unless there is a fault.
RE: Shack Surge Protection  
by K9MHZ on December 28, 2017 Mail this to a friend!
Yep. Ground is ground, neutral is power.
RE: Shack Surge Protection  
by K6AER on December 28, 2017 Mail this to a friend!
Most homes wired for 240 volts have two hot, split phase (120 Volt) and a common ground return. No green safety ground is present. On panels the safety green are connected to the common return ground.

RE: Shack Surge Protection  
by K9MHZ on December 29, 2017 Mail this to a friend!
What comes into your house are two hots and a NEUTRAL. GROUNDING is done at your house panel and distributed throughout your house for safety and GFIs among other things. White/neutral must be considered a power lead, even though it's not hot. Metal cases especially (toasters, major appliances) will have the ground tied to them directly, and have a three-pronged power plug (or four-pronged in the cases of high current, 240-volt items).

My 240-volt upright air compressor has just a dual contactor manual latching relay for ON/OFF. So, it's wired with each 120-volt phase (240-volts total) to its own contact that moves with the other one simultaneously. The GROUND only is connected to the compressor metal. That's white NEUTRAL used.

A dryer, range, etc is wired for 240 volts due to the heavy currents in the heating elements. Added is the white NEUTRAL to tap off some 120-volt low current for control circuits, clock, etc. The GROUND only is still wired to the metal case, while the NEUTRAL is being used for lower power purposes.

Take that white/neutral off your metal case, and you're in business.
RE: Shack Surge Protection  
by SWMAN on December 29, 2017 Mail this to a friend!
I believe that MHZ just said it best and most easy to understand.
RE: Shack Surge Protection  
by K2JVI on December 29, 2017 Mail this to a friend!
A bit of history-as many of you know it was common to see 3-pronged connections for electric dryers and ranges. This all changed in 1996-when the N.E.C. was amended and required the neutrals and grounds to be separated on such connections. Before 1996, the code allowed the safety ground to be connected to the neutral in the above circumstances. The concern is in situations if the neutral was severed, it would create a hot chassis situation. Example; say you lost the neutral connection at the main panel(the main neutral going to the utility on the meter side), and you have a dryer or a range connected in the old manner, all of the neutral current in the house would be present at the metal chassis and someone could accidently complete the circuit to ground(touching the chassis, bare feet, wet floor, you get the picture) and ZAP!
That's because the chassis is definitely floating(not grounded).
RE: Shack Surge Protection  
by AA4PB on December 29, 2017 Mail this to a friend!
A green or non-insulated safety ground is ALWAYS required unless the equipment case is double-insulated. Some equipment operating on 240V does not require a neutral so the power cord will have 3 wires (two hots and a ground). Other equipment needs both 240V and 120V so it requires a neutral as well as the safety ground. In that case the power cord will require 4 conductors (two hots, a neutral, and a ground).

In no case are you permitted to have normal operating currents flowing in the grounding conductor per the current NEC.

RE: Shack Surge Protection  
by K9MHZ on December 29, 2017 Mail this to a friend!
(Veering a little) And then there were those who did the bootleg ground trick in wiring their houses. Yikes, bigtime.
RE: Shack Surge Protection  
by SWMAN on December 31, 2017 Mail this to a friend!
Would you explain the Bootleg Ground Trick a bit. Not sure what that is. Thanks
RE: Shack Surge Protection  
by W6EM on December 31, 2017 Mail this to a friend!
A couple of comments. Good to be concerned about surge protection.

Your preference for fuses needs further discussion. First off, both breakers and fuses have what are called “time-current characteristic curves,” which are log-log plots of current (vertically) and time (horizontally) displaying the values of current and time beyond which the device will open. And, fuses can be slower than breakers. It just depends on the curve slopes of the links.

Your protective device ahead of the surge arrester should be chosen so that it is slow enough to not open from surge-caused clamping current, yet fast enough to open from a continuous fault to prevent a circuit overload. Chances are, if you are on a 30A or 40A breaker-protected 240V branch circuit, the circuit protection in the panel will trip as well, unless you are at least 25 to 30% below their minimum trip values. In the world of overcurrent protection, something called a “coordination study” is performed, using the time-current curves for breakers and fuses that are in series, to make sure that there will be enough time so that only the device closest to the fault will open, and not the next level. Avoids confusion in finding the fault.

Personally, in your application, I would use a 2-pole breaker. Why? Because it is safer. Here’s just one possible scenario. Since you have two 120V outlets beyond the fuses, if you were to have a fault in one of the two 120V outlet circuits, only one fuse would blow. Under a possible situation, with your 240V linear turned on, you would back feed the fault via the primary windings of the linear’s filament and high voltage transformers if they were turned on. Possibly causing someone thinking that the power was off to touch something and get a serious shock. One of the reasons that the NEC requires all 240V appliance circuits to be protected by 2-pole, gang-operated breakers. And, the same case where 2 different hot leg circuits are brought into the same box, such as garbage disposals and dish washers, as they often are.

Good luck with it and stay safe. Do separate the ground and neutral. Very important, as others have said.

In one of my prior "lives" several of us investigated a structure fire which started in a newly installed main panel. It was caused by an open neutral on the incoming utility wires. The electrician had installed a surge arrester ahead of the 2-pole main breaker. No fuses or breaker ahead of the arrester. The neutral bus in the panel was free to swing, based on load and did so to a high (circa 240V on one 120V leg) causing its MOV to short and hold the fault. As is usually the case, the ground rod was useless as a back-up return path to the utility transformer (the NEC allows up to 25 ohms grounding electrode resistance). It could have been worse had the surge arrester not eventually burnt itself in the clear.



RE: Shack Surge Protection  
by W6EM on December 31, 2017 Mail this to a friend!
Ah, yes, age does matter..... Time axis is vertical. Current is horizontal. One thing that becomes obvious when you look at a few of them is that the "rated" amount of current can flow for a very long time before a trip or link opens.....

Shack Surge Protection  
by NO6L on January 1, 2018 Mail this to a friend!
Not safe at all.

The unsafe grounding was covered, so nothing to say there.

Something I noticed, too. Proper component selection. You used 15 amp rated 120V duplex sockets on a circuit rated for 30 due to the fuses. Same with the 240V, it's not rated for 30 amps either. You should have used a four fuse or breaker panel as per code if this was installed in a structure. Two 20 amp fuses for 20 amp duplexes and two twenties for a twenty amp 240v socket. This would also make it easier to add another, or two, 120v duplexes to eliminate the need for multi tap extension cords and adapters, eliminating failure points and fire/electrical hazards.
RE: Shack Surge Protection  
by K6AER on January 1, 2018 Mail this to a friend!
This was built and to keep it simple. Goal was to keep line surges from getting to the equipment. I understand that if the common return opens, that the safety ground will have voltage on it if the split phase loads are not equal. The same thing can happen to you home if the common to the pole transformer opens up to the breaker panel. There is no safety ground to the pole pig. The closest thing is the panel ground rod and in my case it had an impedance of 35 ohms. On a high amperage load that will do little to keep the common anywhere near zero volts. Safety ground is a nice idea but with out a low ground impedance at the panel it does nothing.

In my case the ham shack was located in an upstairs room in an old house with two wire cotton wiring. For some reason there was a 240 volt line up there but the wiring was run about the time Hover was president. My only option was to run a separate green wire ground to the semi, non-grounded fuse panel. I guess in 1930 they did not put ground rods on main fuse panels. In addition, the ground impedance at the panel measured 65 ohms. Not good. That when I added the separate ground bolt to the box and grounded to the cast iron water pipes. Measured impedance then dropped to 7 ohms.

You are correct that the 120 volt receptacles should have had separate fuses but at this point I was not trying to put in a new remote panel but to protect the equipment from lightning surges. The 120
volt outlets just ran the IC-7300 and my laptop. I was not going to pull 30 amps from the plug.

I have since moved from the old house and my new home is all up to code. Still the basic box design did what it was designed for and protected my equipment from future lightning strikes in Michigan.

Remember the NEC code is designed to bring electrical installations to a common level but unless you are going to rewire a 80 year old home you have to do what is best and practical.
RE: Shack Surge Protection  
by W6EM on January 1, 2018 Mail this to a friend!
I thought per his diagram there were two 20A fuses??
The 240V NEMA 6-20R is a 20A rated socket. And, if using 15A rated outlets, as in a 5-15R, they do have 20A bus ratings internally, so placing them on 20A circuits is permissible.

Should have been a 2-pole breaker instead of the fuses, but the 30A breaker in the main panel would probably have tripped anyway for most faults.

As for ground rod ground resistance, how did you measure it? With a fall of potential test set, or with a clamp on ground resistance meter? Just curious. Not surprised that its high. If using an FOP set, to get an accurate reading, you have to disconnect the rod from your panel.....which could be a problem.

There is/are ground rods driven at the base of poles or inside the secondary compartment of utility pad mounted transformers. However, often times a #6AWG is the conductor used to attach the transformer neutral to the ground rod. A shaky replacement for an open service drop neutral. The purpose of the utility rod is more for bonding/draining insulator current to ground than as a safety for an open neutral.

RE: Shack Surge Protection  
by K6AER on January 1, 2018 Mail this to a friend!
I used a AEMC 3640 test set with probes set at 60 and 100 feet.
RE: Shack Surge Protection  
by W6EM on January 4, 2018 Mail this to a friend!
A good choice, which apparently filters out 60Hz currents, which some of the older sets didn't do. And it uses a generator with a different frequency for the test measurements.

A lot of hams seem to think that driven ground rods have inherently very low earth resistance, which your work shows they don't have.

That's why bonding, effectively, is the most important part of surge protection.
RE: Shack Surge Protection  
by K6AER on January 5, 2018 Mail this to a friend!
I bought the test set to check cell tower installations and found that conventional wisdom and NEC codes did not in some cases do the job.

While working as principal engineer for a cell phone company we had over 10,000 strikes on 190,000 cell sites a year. Less than 20 would fall off line if the grounding was done properly.

In some cases Hagger would come out and custom design the grounding for the site application. We could no depend on the power company to provide a common line on their feed with proper grounding in many cases.
Shack Surge Protection  
by VA3WAO on January 11, 2018 Mail this to a friend!
Just a comment

I am a project manager and estimator for an Electrical Company in Canada that works for the largest Communications Company in Canada. I have put literally thousands of these things in, but commercial versions.

With Surge Protectors, you want those things hanging in to the bitter end! Smoking if they have to be! That is why the Eaton protector you have is full of silca sand, in case the MOV's burst. The fuses you are using are designed to blow in approximately half a cycle, a breaker would probably hold for 2 or 3 seconds on an overload. Well, we really don't care about current when we are talking about TVSS's, surge suppressors as we are worried about Voltage Transients and not current! Voltage spikes, Voltage Harmonic transients and of course lightning!

Frankly, if electrical code allowed it, I would hard wire TVSS's right to the main disconnect or breaker in a panel with no other protection than the main! The longer power is applied to a TVSS the longer your circuit is protected. Now this really doesn't apply hard to the model of suppressor you have purchased, but still, the longer that thing is accepting power, the more likely your system is protected. I have pulled these things out, the same one as yours, on smaller sites and they are just black and blue and burnt, but the $100's of K in equipment was still running fine!

I would lose the cord, wire it directly to the fuses and remove the ground screw from the neutral block in the disconnect. Wires into the TVSS should be shortest possible, and rounded sweeping bends, not kinked bends. With the dryer cord you have on and not knowing how far the plug is from the disconnect, I am going to hedge a bet that the suppressor is only doing about half the job its supposed to do.

I have a Siemens First Surge on my Main Panel at 140kA per phase and 100kA on all my panels there after, in my shop and my shack. Otherwise you did good, you have some surge protection and some is better than none and will probably protect you up to a lightning strike.Thanks for the good article and giving the community the heads up! Surge suppression and grounding go a long way in this hobby of ours!
Shack Surge Protection  
by KC2MMI on January 25, 2018 Mail this to a friend!
If anyone is looking into fine points like 130v vs 140v devices, do also check your mains voltage first. In the US, as best I could tell it is federally regulated as actually 117 volts, plus or minus ten percent. In practice, you may find anything from 110 to 125 being common, and of course "220/240" lines will have similar differences.

If your house voltage is uncomfortably off spec, call the power company, it is often either a bad transformer or other problem in the lines that they can and will come out and correct.

Their main criteria is "Yeah, but your light bulbs work?" and that's about it. Anything more, you have to ask for.
Shack Surge Protection  
by KD5PKS on January 30, 2018 Mail this to a friend!
For a little more than the $120, you could get a professional quality whole house surge protector. This would start acting on the surge at your supply panel and not after the surge is already on your home's wiring system. Maybe I don't uderstand the schematic, but is the ground lug connected to a nearby ground rod? What I find concerning, is the surge gets on your home's wiring, travels all the way to your hamshack, encounters the surge protector which engages and routes the surge to ground, back through your home to the main panel ground. Even if you have a bonded ground rod near your shack, you're still letting the surge run throughout the house to possibly damage anything else in it's path to ground through your hamshack.
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