Hi all,
I’m currently taking the Electrical Inspections Course, and am looking at the bonding connections at the water pipes. Looks like the cold water pipe has a bonding jumper going to the main service panelboard, however, the hot water pipe does not have a jumper to the cold water pipe or to the panelboard. Is this a defect or does an instant hot water boiler have some kind of bonding jumper integrated into it? Oh, and it is an 8awg bonding jumper. It should be a 4awg, right?
It is not a defect, but that doesn’t mean that having a jumper wouldn’t be a good idea.
There are multiple places where normally non current carrying conductive components are electrically connected, providing electrical continuity throughout. Also, domestic water supplies naturally contain electrolytes that make the water conductive (pure water is a very poor conductor).
Even with dialectic fittings you will usually find continuity between any two conductive components between the electrical and plumbing systems.
Adding a jumper will add another layer of protection in a metallic plumbing system, but it isn’t necessary from a practical viewpoint.
I’ve known a few electricians who routinely put a jumper across the water heater, but most don’t.
As for the gauge of the conductor, that’s really a moot point since the jumper is supplemental anyway. Any size will do.
Morning, Vlad! Welcome to the InterNACHI message board.
Good luck with your studies.
As to your question pertaining to, bonding connections at the water pipes. George Wells InterNACHI Lifetime Member, Inspector Hall of Fame Inductee (2016), InterNACHI Great Lakes Chapter President (2004-present), Forensic Electrical Consultant and Investigator, Bachelor of Science in Electrical, Engineering, MBA, Journeyman Electrician (since 1978), Licensed Master Electrician/Electrical Contractor (since 1981) is a great resource for all electrical questions.
As well, “George Wells Your The Best!”
I am sure George would not mind you reaching out to him if you have any questions. George was an instructor until recently.
The idea behind bonding copper, “Cu” and atomic number 29 on the periodic table, potable domestic water supply pipe lines, is to provide a safe electrical continuity path throughout.
I read, metallic water supply lines, generally require bonding to the electrical grounding system for safety and to comply with electrical codes. This should not be over looked during a home inspection. I would also measure the AWG of the Equipment Grounding Conductor, within a specific distance of where the pipe entered the building and on the supply side of the meter. It was for the fans 
As for SharkBite fittings on metallic domestic water supply lines and appliances therein. The SharkBite fitting breaks the ground/bond continuity. I would recommend a bonding jumper to insure visible fiscal a ground/bond near the appliance in my report.
Remember: Limitations. Limitations prevent us from seeing what is further upstream and downstream most times.
As for the bonding jumpers size or AWG.
The size of a bonding jumper for a metal water supply system pipes depends on the size of the largest ungrounded service conductor. Table 250.66 in the National Electrical Code (NEC).
From SharkBite:
SharkBite Grounding on Copper Pipe/s.
When connecting a SharkBite Universal fitting to a copper piping system, install a copper jumper cable to ensure proper grounding. SharkBite Universal fittings are not an electrically continuous fitting.
