I was about 10 years old when I first learned just how important grounding is. My older brother had a garage band, and you couldn't have one of those back then without having a Bogen dual column PA system with two 8-inch speakers in each column. Nor could you have a legit garage band without the requisite electric guitars. And it goes without saying that no self-respecting garage band could exist without a garage. Our garage had a concrete floor with no carpeting or fancy epoxy paint covering; just bare, unadulterated concrete. Growing up deep in South Texas, we had little use for shoes from the end of May until the beginning of September, and then only during the week. See where I'm going with this?
Watching my brother's band play was great, but playing with his gear was magical. In fact, you could say that it was electrifying. When I strapped on that cherry red hollow-body guitar and flipped on the power switch, I would often see stars…and sparks. Literally. It's a wonder I lived to tell about it.
It wasn't until later that we figured out that if you put a piece of carpet down on the floor where you stood when you played that guitar that there would be more jam and less D@MN! But that didn't help when you put your lips to the microphone and touched the guitar strings. I should have been a drummer. But then I wouldn't have been so curious about grounding.
Grounding and Bonding
Grounding and bonding are among the most important things to know about a power distribution system, because they can keep ourselves and everybody around us safe while we're using electricity. Most of us know what we know about grounding and bonding through experience and perhaps from what we've learned from other people. But very often that's not enough. There is a lot to know about this subject, and the more I read about it, the more I find out there is to know.
For starters, there's the language. When I first started reading about grounding systems, there were a lot of terms that I took for granted, that I thought I understood, but I'm finding out I often misunderstood. There are very specific terms in the codes and regulations that are used in order to make clear distinctions. And though the intent is to be clear, what I've found is that it's often confusing until you parse each word out. A good example is the distinction between the grounding conductor and the grounded conductor. The grounding conductor is the green wire (or green with a yellow stripe or bare copper), and the grounded wire is the white wire or neutral. It would be much simpler if they would just call them the green wire and the white wire, but I'm sure codes and regulations prohibit that; otherwise it might be too clear.
Needed: More Pictures
There are other terms that defy comprehension on the first read-through. And to make matters worse, the codes and regs are not illustrated – not one photo, video, cartoon or stick figure in the entire book. So if you just want to look at the pictures you're out of luck. Sometimes reading codes and regulations brings a whole new dimension to the phrase "We're from the government and we're here to help."
I'm all about illustrations. You can talk until your face is in full CTB and I might get it; but draw me a cartoon and we just might make happy hour. A picture is worth a thousand words, so I'll be asking for double pay for this column. The illustration accompanying this article is really the meat and the rest is the appetizer.
Once you've digested the art, see if these terms make more sense to you:
Service – the conductors and equipment supplying power from the utility. We typically tie into a disconnect or company switch for service.
Service Entrance – the point at which the supply conductors enter the building. That's typically where you'll find the disconnect.
Main Bonding Jumper – a conductor that connects the neutral bus and the grounding bus. This is a very important part of the grounding system.
Grounding Electrode – the ground rod, grounding plate, or other acceptable connection to earth. Volumes have been written about what you can and cannot use for a grounding or earthing electrode. Read up.
Grounding Conductor – the green conductor (in the vast majority of our applications).
Grounded Conductor – the white conductor (in the vast majority of our applications).
Of course, these are loose definitions and not legal-speak. They are designed to give you a basic understanding of the parts of a grounding system. To get a thorough understanding you really should read the codes and regulations. And afterwards, when you're thoroughly confused, check out a book called Soare's Book on Grounding and Bonding. (Shameless plug alert – now available at plsnbookshelf.com ). It really is an excellent book and the latest edition is even better than the last; it has a lot more pictures.
