Probably is easier or less cost then trying to measure resistance of the elecrode (if there is one). But if there is equipment "likely to energize" the steel you need to bond it anyway. But older construction like that likely does not have steel in the column that ties into anything that makes it an elecrode. If it were newer poured concrete column with reinforcing steel in it - the chance of it being an qualifying electrode increases. If anything it may be tied to a CEE in a footing at very least - but IMO you only have a CEE and not a building steel electrode in that case, and one GEC is suitable for both the CEE and bonding the steel should it be subject to becoming enerized - unless it can be energized by a circuit that needs larger then a 4 AWG EGC.OK. Here is what I have on this job. From what I can determine the steel structure is resting on the pilaster. It looks as though the iron workers inserted threaded rod into the pilaster, installed a bed of concrete, smoothed it over and bolted the steel framework onto the threaded rod. To be safe I'm thinking we'll need to bond the service to it. Does anyone disagree ? Thanks.
I agree, but I believe I mentioned earlier that it is not so likely to become energized in a situaiton where those steel trusses have a ceiling below them and no wiring is installed in the attic space - in that situation I would take a firm stand against any inspector that tries to tell me they are likely to become energized, but if steel raceways are attached to those steel framing members it is much more difficult to make a claim they will or will not become energized. If they do become energized so does the steel raceway, which really can happen when you have lost neutral on the service conductors event.
I don't know where he came up with 3' of contact but I remember being in a CEU class where a rep from the state specifically mentioned that it had to come in contact with the earth. That doesn't mean the rod has to be driven straight down but by the same token it also doesn't mean that you can lay the rod on the ground and throw some dirt on top of it. I partnered with another EC so it's his call as to whether he wants to call the state on this or just install a CEE. We'll see what happens.
I don't have any idea what the three feet of contact is about, all eight feet of the rod has to be in the earth, and yes you can lay the rod in a trench and throw dirt on top of it.
I wasn't thinking about a trench when I made that comment. I meant that you can't just lay a rod on the earth's surface and merely cover it up with a thin layer of dirt. I wasn't thinking "out of the box". In addition my comment about laying an 8' rod below the floor and covering it with cement isn't going to be considered a CEE either. According to 250.52(3)(1) it has to be 20' in length in order to be considered a CEE.
