Reinforcing Steel Electrodes
This change NEC (250.50) will dramatically change many aspects of trade sequencing, with severe consequences for any builder who fails to comply with the new rule. The 13 paragraphs that follow are adapted from letters made available to all licensed construction supervisors and building commissioners in Massachusetts.
A forthcoming change in the Massachusetts Electrical Code will, in many cases, dramatically change the way general contractors sequence the order of trades with respect to electrical work in particular. We believe that timely communication to this effect is crucial to the orderly completion of any work that will involve the placement of reinforcing steel in a concrete footing.
The 2005 NEC as adopted in July of 2004 by the National Fire Protection Association now requires that all qualifying concrete-encased grounding electrodes be connected to the grounding system for the building, unless the building is an already existing structure. A qualifying concrete-encased, reinforcing-steel electrode is
At least ?-in. in diameter (corresponding to a No. 4 bar, or larger); At least 20 ft in length (this measurement includes multiple pieces of steel if they are tied together); and Placed ?within and near the bottom of a concrete foundation or footing that is in direct contact with the earth.? Not encapsulated in nonconductive coatings for corrosion resistance, such as epoxy.
This means, in turn, that for new construction, a connection must be made to such steel electrodes (where they exist) using a 4 AWG or larger copper grounding electrode conductor, with the other end of the wire arranged to leave the concrete at some convenient point.
The means for connection must be listed by a qualified testing laboratory (such as UL) both with respect to suitability for embedment in the concrete as well as for use with reinforcing steel.
Many electricians use wire long enough to reach from the foundation to the intended electrical service location, avoiding the need for a subsequent connection. Another approach involves bringing a segment of reinforcing steel out of the pour that is tightly tied to the segment(s) making up the qualified electrode.
The electrical connections are covered under MGL Chapter 141 and Chapter 143 Section 3L. Therefore the connection to the electrode must be done by a licensed electrician, which need not be the same person or firm responsible for the other work in the building.
Further, this work, including verification of the suitability of the tie wiring on the components of the electrode, must be inspected by a municipal Inspector of Wires prior to the completion of the concrete pour. If this process is not followed, the consequences could be severe, potentially resulting in a requirement to dismantle and rebuild the foundation.
This provision of the 2005 National Electrical Code is not being amended in Massachusetts. It, along with all other provisions of the 2005 Massachusetts Electrical Code, will apply to all electrical work in Massachusetts for which an electrical permit issues on or after January 1, 2005. We hope that you will assist us in making a smooth transition to the new requirement.
You may want to consider establishing a relationship with a licensed electrical contractor well in advance, at least with respect to being available to apply for the required electrical permits and having the required stock and personnel available so your construction schedules are not impeded.
Please note that this is not a requirement to install a concrete-encased electrode at any building (although it is always permitted). This is a requirement to connect to such an electrode if it will exist because of engineering design.
This work qualifies under Rule 10 of the Massachusetts Electrical Code for inspection within 24 hours of notice (weekends and holidays excluded) to the municipal Inspector of Wires, so construction should not be delayed for that reason. In fact, if the inspection does not take place within this time, the concrete pour can proceed without the completion of the inspection.
In a nutshell, IF THERE WILL BE REINFORCING STEEL IN THE FOOTING OR BOTTOM OF THE FOUNDATION IN ANY BUILDING you erect after the new year, then THERE MUST BE AN ELECTRICAL CONNECTION MADE (or arranged for if the steel will extend out of the concrete) AND AN ELECTRICAL INSPECTION PERFORMED PRIOR TO THE CONCRETE POUR.
Concrete-encased electrodes have a long history (over a half-century) of superior performance with respect to creating an effective ground reference. In New England soils, they are far superior to the any likely alternative, particularly with the increasing use of nonmetallic water piping systems. This change is squarely in the interest of public safety, so we want to do what we can to make its implementation as smooth as possible.
) And inspectors don't seem to know about it or care. Is any one else experiencing this?
