Category Archives: Technical

Amateur Radio Station Grounding – Ground Electrodes

Up until now in the previous blog entries we have seen that the amateur station must be installed in accordance to the National Electrical Code. For those of you reading this that are outside the jurisdiction of the NEC and NFPA, I apologize in advance as the subject will be geared towards hams in the USA. That does not mean that you shouldn’t consider the NEC as good, basic guidelines, but you need to be ensure that your station is constructed in compliance of the regulatory body or the local requirements in your area.

Let’s get started.

How do we install a station so that it complies with NEC? We will first start at the ground electrode system, or as most might know it: the ground rods. That’s where most folks begin in this journey and where most folks deviate and create problems.

Ground Electrodes:

What is a ground electrode? This is defined in NEC Article 100 as “A conducting object through which a direct connection to the earth is established.”. It is most common to hear folks refer to electrodes as ground rods, or just rods. Advanced or exotic forms of electrodes are beyond the scope of this blog.

What qualifies as a grounding electrode? As per 250.52 (some material removed for brevity please reference NEC for original text prior to performing any system design or work):

250.52 Grounding Electrodes.

(A) Electrodes Permitted for Grounding.

  1. Metal Underground Water Pipe. A metal underground water pipe in direct contact with the earth for 3.0 m (10ft) or more (including any metal well casing bonded to the pipe) and electrically continuous to the points of connection of the grounding electrode conductor and the bonding conductor(s) or jumper(s), if installed. (Note: There are specific requirements that must be met in order to utilize underground water pipes. Please reference appropriate sections.)

  1. Metal Frame of the Building or Structure. The metal frame of the building or structure that is connected to the earth by one or more of the following methods:

  1. At least one structural metal member that is in direct contact with the earth for 3.0 m (10 ft) or more, with or without concrete encasement.

  1. Hold-down bolts securing the structural steel column that are connected to a concrete-encased electrode that complies with 2S0.52(A)(3) and is located in the support footing or foundation. The hold-down bolts shall be connected to the concrete-encased electrode by welding, exothermic welding, the usual steel tie wires, or other approved means.

  1. Concrete-Encased Electrode. A concrete-encased electrode shall consist of at least 6.0 m (20 ft) of either (1) or (2):

    (1) One or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (V2 in.) in diameter, installed in one continuous 6.0 m (20 ft) length, or if in multiple pieces connected together by the usual steel tie wires, exothermic welding, welding, or other effective means to create a 6.0 m (20 ft) or greater length; or

    (2) Bare copper conductor not smaller than 4 AWG Metallic components shall be encased by at least 50 mm (2 in.) of concrete and shall be located horizontally within that portion of a concrete foundation or footing that is in direct contact with the earth or within vertical foundations or structural components or members that are in direct contact with the earth. If multiple concrete-encased electrodes are present at a building or structure, it shall be permissible to bond only one into the grounding electrode system. Informational Note: Concrete installed with insulation, vapor barriers, films or similar items separating the concrete from the earth is not considered to be in “direct contact” with the earth.

  1. Ground Ring. A ground ring encircling the building or structure, in direct contact with the earth, consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 2 AWG.

  1. Rod and Pipe Electrodes. Rod and pipe electrodes shall not be less than 2.44 m (8 ft) in length and shall consist of the following materials.

(a) Grounding electrodes of pipe or conduit shall not be smaller than metric designator 21 (trade size 3/4) and, where of steel, shall have the outer surface galvanized or otherwise metal- coated for corrosion protection.

(b) Rod-type grounding electrodes of stainless steel and copper or zinc coated steel shall be at least 15.87 mm (5/8 in.) in diameter, unless listed.

  1. Other Listed Electrodes. Other listed grounding electrodes shall be permitted.

  1. Plate Electrodes. Each plate electrode shall expose not less than 0.186 m2 (2 ft2) of surface to exterior soil. Electrodes of bare or conductively coated iron or steel plates shall be at least 6.4 mm (1/4 in.) in thickness. Solid, uncoated electrodes of nonferrous metal shall be at least 1.5 mm (0.06 in.) in thickness.

  1. Other Local Metal Underground Systems or Structures. Other local metal underground systems or structures such as piping systems, underground tanks, and underground metal well casings that are not bonded to a metal water pipe.

(B) Not Permitted for Use as Grounding Electrodes. The following systems and materials shall not be used as grounding electrodes:

  1. Metal underground gas piping systems

  1. Aluminum

Wow, that was a lot of information!

So we know what ground electrodes are now. For our purposes, we generally use ground rods, 8′ long by 5/8″ in diameter, copper clad steel. They are not solid copper, as some folks might think. They look like they are, but  if you examine each end of the rod you can clearly see it is steel-cored. If rods were solid copper, they would bend as soon as you tried to put them into the earth. Copper itself is very malleable; try using a sledge hammer to drive a 3/4″ copper pipe, it will bend in half.

As for terminology, lets make sure we use the right terms. The ground rods are not stakes, I see them referred to that a lot, and it is very confusing. Let’s use the right terms, so we can sound more like professionals and not like a bunch of blithering idiots. We want to be treated as professionals, so lets act like one, or at least try to. They are called ground electrodes, or just simply put, ground rods.

With all of that said, I think most folks will simply install an 8-foot or longer ground rod at the entry of their station. That’s about the simplest you can do, unless you happen to be lucky enough to have the antenna and control lines entering the station/home/shed/shanty at the same point where the electrical utility is. In that case, the electrode(s) are already installed and all that must be done is to properly bond everything to that point.

For those amateurs that may be in a situation where they have one or many of the other options available, unless it is easily done (i.e. there is a stub of wire from the UFER in the foundation or there is a metal beam available, etc), it is best to still install an additional electrode and bond that back to the other electrodes in the system (code requirement).

One important point to note, is that in no where was it stated that it is approved to use a piece of copper pipe. I see a lot of hams using copper pipes that they are ‘jetting’ into the earth using water. That might work, and seems like a good idea, except it doesn’t meet code requirements. Code states that a pipe can be used provided that it is 3/4” trade size diameter, galvanized steel, 8 feet in length, and is driven.

Exotic electrodes such as “chemical rods”, seem like they are copper pipes with electrolytic salts in them and they are UL-Listed and therefore approved by the NEC to be used as ground electrodes, in all areas of the ground electrode system.

Installation of the electrode(s):

Now that we have the ground electrode(s), we can install them. The first task to do is we must call the utility location service and have the location of the utilities marked. Some areas refer to this as DigLine, OneCall, or some other term. This is to reduce the chances of damage to the underground utilities during the installation of the electrode(s). It is simple to do, and it is the law.

Once the utilities are located, we have determined and ensured the location of the rods will not impact any underground utilities, and it is safe to do so (not during a lightning storm), the next thing is we need to some how get this electrode into the earth. This is the fun part. Sometimes.

This can be done using a sledge hammer, a fence post driver, or my favorite, a power or pneumatic tool. It really doesn’t matter how it is done, but it needs to be done such that it meets code requirements. Those are: if practicable, below permanent moisture level, the rod must not be cut down or shortened, and the head should not be deformed.

It is important to note that any supplemental electrodes (those electrodes above and beyond one, or the first driven electrode in the system, i.e. the utility entry electrode found at homes and other buildings) shall not be less than 6 feet apart from any other electrode of another grounding system (NEC 250.53 (A) 1 through 3). Again, here we have an electrical code requirement.

Something to be noted, is that it is widely understood that you actually want to have these electrodes further apart than 6-feet; something more along the lines of 8 to 15 feet, but ideally 10 to 15 feet. This is not a place for any debate on the subject or to go in-depth as to why, so we will leave it at that. Don’t put electrodes closer than 6 feet. Period.

Rods shall be installed in a vertical manner, straight down into the earth, or if that is not possible due to rocks, installed at a no more than a 45-degree angle. If you hit rock, you’ll need to start again, in a different location. There is a stipulation for installing electrodes horizontally, however that requires additional considerations, beyond the scope of this blog at this time.

Pro tip: Install the ground conductor clamp (the acorn clamp) over the top of the rod and down onto it a few inches and cinch the bolt down. You don’t want to try and do this after the rod has been driven and the head is slightly mashed/deformed (it happens).

Pro tip: The way I always advocate that rods are installed regardless of practicable methods, is that the rod head should be below frost line, or at least 12-18” down in the earth. This also allows you to install inspection wells (use a small 8” circular sprinkler valve box) over the top of the rods so that you can properly inspect the acorn clamp yearly to ensure it has not worked its way loose. This of course becomes irrelevant if you are making your rod-to-wire connections using exothermic welds. If that is the case, simply bury the head of the rod below grade, ideally below the frost line.

Continue to add ground electrodes to your system until you have installed the required amount as per your system design and in accordance with the guidelines set forth by the NEC. This might be one rod at the station entry, or a series of rods in a ring configuration, counterpoise configuration, etc.

In the next blog entry, we will address connecting the rods together.

Until next time, 73 de ke7ii sk sk sk

Amateur Radio Station Grounding – National Electrical Code

First and foremost, we are required to comply with National Electrcal Code (hereafter referred to as NEC). This is what all electrical systems and their associated “things” must follow in the United States. All of your home or business electrical systems must be constructed and maintained in accordance with NEC. This electrical code is written with the intent to ensure that life and property is protected.

In fact, it is written that the following is the purpose of NEC:

“(A) Practical Safeguarding: The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity.

B) Adequacy: This Code contains provisions considered necessary for safety. Compliance therewith and proper maintenance results in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use.

(C) Intention. This Code is not intended as a design specification or instruction manual for untrained persons.”

Life safety is priority #1. Everything done as part of electrical systems revolves around life safety, from the service main, to the breakers, to the wiring in the walls and the outlets. It (NEC) also covers things like how conductors or wiring should be routed, protected from damage, short circuit and overload protection, and obviously grounding and bonding.

Our little part of the world, amateur radio, is also covered. This is referenced in Article 810 NEC. You will find both receive only, and transceiver systems covered here. The requirements for amateur stations aren’t unique to anything in particular however they do build upon/reflect all of the other requirements in the other sections of the code. You’ll see things like wire size (gauge) requirements are the same here, as they are elsewhere. Additionally, the same requirements for protecting exposed conductors, and using UL-Listed components still stands when being applied to your amateur station. Over time, we will dive deeper into Article 810 and examine it closer. There is a lot in there, and it can be confusing and overwhelming to many folks. For now I will try and summarize some key points, or what I think is important to come away with until I can explain things a little further.

So what does this all mean? It means the station you have at your home or business must meet the requirements of the NEC. A ground system of some sort must be constructed and all antenna masts, lead in conductors, station equipment etc must be bonded to it in accordance to the rules as defined. There are no variations permitted. NEC will state the minimums for things such as wire gauge, ground rod (electrode) lengths, spacing requirements, etc for the system and components and those are expected to be met. Unfortunately for many folks, NEC wasn’t written for the layperson to read and comprehend. Remember earlier, point “C” of the NEC purpose? It was written for engineers and electricians and those working the in trade. It’s expected that one understands that just because the code requires you to say, connect two wires together it doesn’t mean use whatever you have laying around to do this with. Rather, you’re expected to reference the appropriate section for splices in wire or conductors in a given circumstance. Hamming it up is not permitted.

It is important to also understand that NEC is not concerned with how well your station operates. This is of no concern to the NEC. The sheer fact that you can’t talk to that rare dx entity or dxpedition doesn’t mean you can install your station haphazardly or dangerously. The only thing that is important is that the station complies with the rules and therefore be determined to be safe for those who use it or others who might be exposed to it (equipment) or the electrical hazards associated with it.

Your local Authority Having Jurisdiction or AHJ may require details that are more stringent than NEC does. In these cases, you must comply with the more stringent of the two. For example, if your local AHJ says you must not use any conductors smaller than 500MCM and all underground or buried splices must be exothermically welded, then you must comply or expect to deal with the ramifications of non-code compliance. This is a greatly exaggerated example but I give it to make a point.

While we are here I think it is prudent at this point to discuss industry standards. You’ll find a lot of places online or during the discussion of this topic with folks that some may mention references to industry standards such as Motorola R56, or EIA/TIA standards, FAA, NWS, or BICSI, etc. These standards are written with the intent of providing guidance and rules if you will, for communications sites in the industry or otherwise. You’ll find a lot of things that seem excessive such as statements saying “conductor size shall not be smaller than X AWG”. There are scientific reasons why these are called for.

You might say “why don’t they just follow what NEC requires? Why do more? Doesn’t NEC know best?”. Well, the NEC has determined their wire size requirements for example, meet the minimum requirements to provide adequate protection from the electrical hazards that may be encountered. It might seem silly to say “no conductors smaller than #2 AWG may be used” but that requirement for the industry standards is derived from the fact that the industry knows the larger, or coarser wire sizes can conduct more current more effectively during lightning strikes. The purpose of the bonding conductors is to help shunt and direct the excess energy away from the folks who use and maintain communications gear, in addition to the equipment at the site. Unlike NEC, the industry IS concerned with equipment.

You must understand that these standards are not replacing NEC. In fact it is quite the opposite. The standards all are based on NEC, just like your local electrical codes set forth by the AHJ in your area. You’ll never find them saying anything that is not in line with code (at least not intentionally) anywhere. They simply take the minimums and improve on them. And, in all cases these standards provide above-and-beyond protection of life and property when they are applied correctly.

As responsible amateur radio operators, we should strive to meet these industry standards if at all possible whenever possible. However, at a minimum we must comply with NEC and local codes. This means no stand-alone electrode systems, no failing to properly protect lead-in conductors, etc. We will go over these things later on in this series.

I apologize in advance if some of this is long winded, but I feel it is important to address at the start. I cannot stress enough how critical it is to follow the requirements as set forth by the NEC and the AHJ’s. It is not written to be considered excessive or unnecessary. There are sound engineering and scientific reasons for all of it. As I have said before, just because your Elmer or person who you seek advice from says “bah don’t need that it’s all hogwash!” doesn’t relieve you of the requirement to comply with electrical codes. Yes it is expensive, yes it is time consuming and yes it generally results in back breaking labor. However at the end of the day, you can sleep better knowing you have done things right and have tried to protect your station, your family, and yourself the best you can.

 

Until next time, 73 de N7AMD sk sk sk

 

Amateur Radio Station Grounding

Recently there has been a lot of discussion (and arguing) on station grounding at the various “hang outs” online that I frequent, as well as questions directed to me from amateur operators. I think it is time I write a little bit about this, from my own perspective. It seems to me that there is a lot of “stuff” out there on the subject that is mostly good, but there is a lot of bad information which sort of ruins all of the good. There is also the issue of the old mentality “well my elmer did it this way, and his elmer did it that way so I am going to do it that way! Anything else is a waste and not needed. They’ve never had problems so neither will I!”.

misc-are-you-fucking-kidding-me-clean-l

That is about as reckless as you can get, when it comes to protection of life and property. Notice that life came before property. That is a key part to understanding and implementing station grounding.

I will attempt to “cut the crap”, and provide some basic guidance on station grounding in my following blogs. These are to be considered as supplemental guidance if you will, in the design and implementation of the average amateur radio station system ground system. There are the requirements to comply with National Electrical Code (NEC) in the USA and those will be addressed as well. After all, the station ground is required to be compliant with NEC if you reside within the United States. I cannot comment on stations outside the USA as I do not have experience with their regulations or codes.

My goal right now is not to provide the be-all-end-all bible of station grounding, but rather to help folks understand what is required and why.

Stay tuned for more.

FBOM, de N7AMD sk sk sk