We recently upgraded our electric service…had to put in a new panel, etc.
The city inspector came by and said that everything looked good except that we still need to "Bond Hot-Cold-Gas with #6" @ the water heater. My question is why do we need to do that?
Why do we need bonding at the gas water heater
grounding-and-bonding
Related Solutions
The NEC only requires two ground rods if one doesn't suffice the 25ohms requirement. If an additional ground is installed then a minium of 6' spacing is required between them. The only time the neutrals and grounds are allowed to tie together are in the main disconnect. To keep the neutrals and grounds separated, a 4 wire should have been used to feed your sub panel.
Electrical – How to test to make sure the panel is grounded correctly and all the bonding is correct
A continuity test should be sufficient to determine that the grounding wires are connected. Edit- To check for continuity with a multimeter, turn the dial to the a symbol that looks like, ►|. Make sure the probes are in the correct places. Some multimeters have three sockets for two probe wires... if that's the kind of multimeter that you have you need to put one probe in the socket marked ohms (Ω). Then attach or touch the probes to whatever you are checking (for continuity) to find out if they are connected. Some multimeter models make a ringing noise, while other models just display a quick burst of numbers which settle down to zero when the meter senses that the probes are connected (electrically).
But beyond that you should check out the article, how to achieve grounding in poor soil. I'm not suggesting that you have poor soil, but this article illustrates how to check it (with a ground resistance testing instrument) and how to treat poor soil if necessary, and points out some other info about grounding.
Related Topic
- Electrical – Existing 3 wire service feed to sub panel: bonding grounded neutral and ground bars
- Electrical – Grounding 200A Main Panel with Changes to Water & Gas
- Adding second ground rod. Is this an acceptable way of bonding
- Electrical – 3 Phase Grounding
- Bonding CSST to electrical ground system
- Electrical – How to compliantly bond galvanized water pipes if the water heater isn’t an option
Best Answer
Because your water heater has dielectric unions, so the hot and cold plumbing are isolated from each other. Bonding the plumbing, attempts to keep the hot and cold plumbing at the same electrical potential.
If this bond is not in place, it's possible for the hot and cold plumbing to be at different voltage potentials. Which means if you grab a hot and cold handle, you could complete a circuit.
It also allows the plumbing to act as an effective fault current path. So if wiring faults to the plumbing, a breaker will trip.
A jumper should be installed across any other break in the continuity as well, e.g. water meter, nonmetallic plumbing, etc.