The purpose of bonding jumpers is to connect two piping systems together as one. Back in your grandaddys days, hot and cold were two different systems tied together at the water heater. If you removed the heater, or had a bad union connection, you broke the system. With modern day single handle valves there are not two systems. There is one system with hot and cold water being diverted thru it with 3 to 5 junctions.
No, AFAIK the number of piping systems doesn't change when a faucet is replaced.
Is the water coming out of the faucet two different types of water
Yes, one is hot, one is cold.
if you turn on both the hot and cold valves?
Then it's warm :grin:.
If the valve is one assembly that is conductive material would you still put a bonding jumper from the hot and cold supply pipes because you call them two separate systems?
Yes. The faucet may connect those sections under the sink together, but there are very easily PVC appliance connectors that electrically isolate the faucet from any metal piping.
If you have two water heaters piped in series do you now have 3 piping systems?
Maybe, have to ask a plumber.
It is one water system all pressured from the same source (in most cases) with possible electrically isolated sections in the piping including the connection at the water heater.
Our transformer separately derived systems are pressurized from the same source too, but we still consider them separate systems.
If the water heater tank is made of non conductive material then a dielectric union would not be needed unless there is metallic hub for water connections, and then it would depend on the material of the hub.
?? No, not needed
.
Installing a bonding jumper does not hurt anything but is not always required.
Some day when a water heater gets changed the jumper may be required.
My main point, at least with a conductive tank, is that it is required
while the WH is being replaced. Otherwise, the hot water system may not be bonded at that time. Electrically, it matters not if the pipe is empty at that time, it still may become energized.
Some day the piping could be changed and a section of piping may become electrically isolated, how are we supposed to future proof that?
Plumbing inspections and knowledgeable inspectors?
If you are a plumber there may be separate systems, if you are any other trade it is water piping, if you are an electrician it is water piping with possible electrically isolated sections.
Well, I don't
like the isolated sections, but I don't see 250.104(A) as requiring every section of each piping system to be electrically continuous, only that each system be bonded. Unlike 250.52(A)(1).
The danger of outside neutral currnet that exists when removing a water meter should not exist at the water heater if it did we would have many more required bonding jumpers to install.
Not a concern for 250.104, this only concerns faults on the premises wiring.
Is that same section that lists couplings, t's, copper tubing, 90 degree elbows, male adapter etc etc etc. ?
That section actually has nothing to do with what we are talking about here. That section tells you
how you can and can not connect your bonding or grounding conductor to what ever it is you happen to be bonding or grounding not
what requires bonding and grounding.
Those can all be components of a single system, we are not using them for bonding
to the piping.
There is no NEC requirement that specifically mandates a bonding jumper between hot and cold piping systems. It simply does not exist regardless of the whims of some inspectors and the lack of understanding by some electricians.
Maybe. But if you are using the plural for those systems, they each need to be bonded per 250.104(A)(1).