E&S Grounding Solutions is the premier electrical grounding, earthing, and electrical safety consulting firm and contributors to the McGraw-Hill book “Standard Handbook for Electrical Engineers” authoring chapter 24: “Grounding Systems” in the 16th Edition.
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John asks us: One of my junior electricians lost the green bonding screw in an electrical cabinet we are installing. Can I use a regular silver machine screw to replace it?
Allistair asks us: If you Consider a 3.5m long sailing boat, the
sailing boat is made of fiberglass and has a 5m aluminium mast. The mast is
held in place by three steel wire side stays. A mainstay that runs from top of
the mast to the bow of the boat and two side-stays that run from top of the
mast to port and starboard side of the hull. The foot of the mast rest on a
wooden body of the boat, 1m from the bow. Is it safe to sail a sailing boat
during a thunderstorm? Comment on your answer. If you had to design lightning protection for the boat, how would you go about doing it?
Allastairasks us: A structure has two separate earth systems: a
safety earth and an electronics earth. The safety earth is connected to an
earth-mat located 100m away from the structure. The safety earth is locally
earthed. Is this a safe configuration, in terms of lightning safety? Explain
your answer. If it is a problem, propose a solution.
Jeffery asks us: When a residential service is replaced in areas without city water systems, plastic well water line, and ground rods are all that is available, does the requirement change for only a # 6 copper conductor to the rods, being it is now primary gounding electrode and not supllimental. ( say larger home 120/240V, 400(320) Amp?
Melissa tells us: I have two transformers next to an electrical building. A 13.8-4160 and a 4160-480. MV transformer is resistance grounded to 100A. LV is solidly grounded. My engineer is telling me I need a beefy grid around both and it should be modeled as a substation due to the fact a transformer winding may become shorted to the transformer enclosure creating a SLG fault. He says if that happens, 34.4kA will go into the ground and this will create harmful step and touch potentials in about a 100-150ft diameter around the transformer. I don’t know much about this sort of thing, but I know typically, a very simple ground system is put into place, and not one with many many rods and runs of conductor. Can you tell me, not knowing more details, if his argument holds water and I should consider his design? I am told the soil is moderately conductive. 3350 ohm-cm to 6250 ohm-cm.
Thank you for your question regarding Ground-Fault Circuit Interrupter (GFCI) outlets and water coolers, it is our pleasure to help.
The National Electrical Code (NEC) Article 422.51 and 422.52 are very clear on this subject, you must have GFCI protection for water coolers. In fact, machines manufactured after January 1, 2005 must have integrated GFCI protection inside the circuitry of the system (see NEC 422.51). Depending on how your local inspector interprets the code (see NEC 422.52), you may be required to provide a dedicated GFCI outlet, even if the cooler has integral GFCI protection. Continue reading
Thank you for your question regarding 50% ground bars, it is our pleasure to help.
Busways have two ground conductors. One is an actual additional copper or aluminum bus bar in the stack with the phase conductors inside the housing. The other is when the protective metal housing around the bus bars is bonded and used as a ground path. Continue reading
Thank you for your question regarding the welding of steel rebar, it is our pleasure to help.
Not all rebar can be welded, particularly with the exothermic welding process as it must be able to heat the surface of the metal rebar to the melting point in order to ensure adhesion. In general, only steel rebar that is “Grade W” can be welded. Continue reading
Thank you for your question regarding lightning protection and ferrite chokes, it is our pleasure to help.
Ferrite chokes are used to filter common-mode noise and interference on data lines such as CAT5 Ethernet. Ferrites operate on low-power high-frequency signals that are coupled onto the line from neighboring cables or wireless transmissions. They are not designed to protect from high-power surges such as lightning or short-circuit events. In high-power surges, ferrite chokes become saturated and become ineffective as filters. Continue reading
Nilushka asks us: I’m interested in calculating the voltage variation of the soil, inside a mesh in a grounding grid. currently I have modeled a grounding grid including vertical rods using PSCAD software so the voltage at intersection points can be measured. However I need a method to study the voltage variation within a given mesh so the voltage distribution in the soil can be explained using some equations. Can you guide me towards a solution.