I believe the intent is to maintain the electrical continuity of ground between the pipe sections.
I understand that part. Just don't understand why it needs to go back the building ground.
The document that is shown states - that it is a manufacturer's requirement. So in order not to be in violation of NEC 110.3, I would say to do whatever the manufacturer dictates.
I just replied, my comment is being moderated and will not post.
I'm locked out.
These look like Equipment System OEM Installation Instructions. You would have a better understanding of your situation by referencing the Installation Manual of the Manufacturer for the Flow Meter as the Drawing states. There is no Part Number for the Flow Meter provided so I am unable to assist further in those regards.
The Note included for 'Building Ground' also includes '(TYP.2)'. I don't know exactly what that means unless it's simply "Typically 2 Connections" --> do not Jumper. The "Flange" to "match" the Pipe would be an Accessory, most presumably available from the Flow Meter Mfg., with a Part #, depending on the application. The Flange, having a way to specifically connect a Ground Wire, is more than a Standard Flange cobbled up in some way to accommodate the Ground Wire connection (in other words, do not try to fabricate your own Flange Assembly). Lastly, the Flow Meter Mfg. may have alternative methods (such as 'all is good' if the Pipe goes back underground on both sides) but the Equipment System OEM advertised the sure fire solution (or, always works under all circumstances) on the Drawing in the Picture shown.
Magnetic Flow meters require adequate bonding to earth ground in order to eliminate potential noise influences across the measurement being taken by the meter itself. This flow measurement is inferred via a magnetic field being generated between two poles within the tube. As long as the media is conductive, and as flow increases, voltage is generated and measured by integral sensors which is then typically converted into a usable signal such as a pulse (frequency) or mA (4-20). This type of flow primary is susceptible to outside influences and from my experience, all manufacturers recommend proper bonding to ground. This can be especially important in non-metallic piping such as FRP in which "grounding rings" are provided by the manufacturer to help establish this connection across the meter as well as to a local building steel (in the event this is an option. The raceway of course could also be used provided it is installed continuous as required per the NEC. With all this said, bond your Magnetic flow meter to eliminate influences in measurement and overall accuracy as well as false flow measurements... hopes this helps.
If you look on the inside of the flow tube, there will be two pads on each side of the tube. There will be a voltage consisting of a pulse or AC source that is generated between the probes through the media in the tube. If the magnetic flow meter is installed on electrically insulated tubing and the meter body is not grounded, some of the EMF between the probes would be coupled to the meter conductive outer tubing and would thus create a hazard.
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