With the velocity and the known Inner diameter of the MAG meter the flow mate is calculated. Grounding Ring Drawing Link. They are provided in pairs and are installed upstream and downstream of the flow meter. At that point, when the main bonding jumper is installed the one that grounds the neutral bar , the fault current flows from the ground bar through the metal panel frame and through the main bonding jumper to the neutral bar where it splits, and some fault current flows through the grounding-electrode conductor to the utility source.
The remainder flows through the system grounded conductor back to the utility source. If, however, you were to install grounded and grounding conductors to the same grounded terminal in a subpanel, you would be establishing a parallel path for grounded conductor neutral current flow. That is, normal return currents would be present on both the grounded conductor and the grounding conductor, which, in some cases, could be a metal raceway. The AHJ also felt that, where the cable was installed above 7 feet, it was adequately protected.
Bare copper Can the grounded neutral service-entrance conductor be installed as a bare copper conductor in a metal raceway?
NEC Section Is it required to mark the high phase conductor with an orange color? He can be reached at codefaqs earthlink. Don't worry, we'll come to you. By Charlie Trout. About the Author. Charlie Trout Code Contributor. Sign up and Get Connected. Related Stories. Next Up. James G. In the November issue, I wrote about the rewrite of Section Last month, I discussed the grounding and bonding procedures using the grounded conductor at the service equipment and outside utility transformer.
To determine when to use grounding rings or grounding electrodes, the first thing that must be understood is their primary function and even required. The primary function of grounding rings or grounding electrodes is to provide the required SG connection when an unlined metal process pipe is not available.
Grounding rings are metal rings that make contact with the process liquid. These rings are installed between the process pipe and the magnetic flow tube. Examples with detailed illustrations are shown in this article. Figure 2. Typical wafer-style magmeter flowtube with supplied SG wires installed in flanged metal process pipe. Figure 3. Flanged-style magmeter flowtube with SG grounding straps and rings installed in nonmetallic pipe.
When using flow tubes that already contain grounding electrodes, grounding rings are generally not required. Contact us to determine which flow tube models are available with grounding rings and grounding electrodes. For many of the more hazardous process liquid applications, magnetic flowmeter systems are often the preferred technology simply because they are available with numerous liner and exotic electrode material choices, thus providing compatibility with many hazardous chemicals.
If grounding rings or grounding electrodes are required, they should be made from the same material as the measuring electrode based on chemical compatibility with the process liquid. In hazardous process liquid applications, the adjacent process piping is usually nonmetallic or lined.
Because grounding rings made from exotic materials are rather expensive, grounding electrodes can offer substantial cost savings over grounding rings and provide easier installation with fewer leak-points. For decades, two grounding rings were always the recommendation when required for magnetic flow meters.
When using older style legacy magnetic flow transmitters, this is still true. However, with current intelligent microprocessor-based magnetic flow transmitters, two grounding rings are no longer necessary, as the same level of zero stability and accuracy can be provided with just one grounding ring. This not only reduces the overall cost of materials but also makes installation easier. The grounding ring typically installs on the upstream side of the magnetic flow meter.
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