cold water bond location

[michael mckague]

My question is about where the cold water bond should be terminated. Most electricians and inspectors in my area(CT) require it to be terminated where the plastic water lines enter the house. My house is a great example, the electrical service entrance is in one corner and the deep jet well pump(with plastic water lines) is in the opposite, meanwhile a cold water pipe is right near the panel. In this case I ran 75' of # 4 Cu from corner to corner. My concern other than time and material is that a fault anywhere on the copper plumbing system would have a longer route to travel back to the source, and therefore a higher impedance overall.

 

[infinity]

If your simply bonding the metallic water piping system {250.104} the bond can be connected at any accessible point.

 

[kwired]

My question is about where the cold water bond should be terminated. Most electricians and inspectors in my area(CT) require it to be terminated where the plastic water lines enter the house. My house is a great example, the electrical service entrance is in one corner and the deep jet well pump(with plastic water lines) is in the opposite, meanwhile a cold water pipe is right near the panel. In this case I ran 75' of # 4 Cu from corner to corner. My concern other than time and material is that a fault anywhere on the copper plumbing system would have a longer route to travel back to the source, and therefore a higher impedance overall.

For interior metal piping only it can be anyplace you desire that is accessible according to NEC. If the underground piping qualifies as a grounding electrode then it must be within five feet of entance to the building.

As far as longer route and higher impedance in your case, there may be other return paths that actually shorten the path/reduce impedance, like water heater, pressure switch on pumping system, pump, and the fact that copper pipe has a low impedance to start with. What is likely to energize the line? - In most cases it will be circuits with 15 or 20 amp overcurrent protection occasionally a circuit up to 60 amps in a dwelling, not exactly the same as depending on the pipe to carry enough fault current to open a 800+ amp overcurrent device in a commercial/industrial environment. And in the places where that happens you are not always dealing with as small of water piping as you are in typical dwelling either. I would think a 2 inch pipe would carry much more current as compared to a 1/2 or 3/4 inch pipe, without any problems.

 

[Ponchik]

According to 250.104(A)(1) requires that the bonding for water pipe to be sized according to 250.66. But 250.104(b) allows that size of bonding for other metal piping system to be sized according to 250.122.

My question is what is the difference? If all we are doing is bonding and non is being used as an electrode.

Thanks

 

[kwired]

According to 250.104(A)(1) requires that the bonding for water pipe to be sized according to 250.66. But 250.104(b) allows that size of bonding for other metal piping system to be sized according to 250.122.

My question is what is the difference? If all we are doing is bonding and non is being used as an electrode.

Thanks

I have questioned this myself, but never had an answer that makes any logical sense.

 

[cowboyjwc]

I agree with Rob.

 

[gndrod]

egc-gec

egc-gec

According to 250.104(A)(1) requires that the bonding for water pipe to be sized according to 250.66. But 250.104(b) allows that size of bonding for other metal piping system to be sized according to 250.122.

My question is what is the difference? If all we are doing is bonding and non is being used as an electrode.

Thanks

The 250.66 GEC sizing is for grounding electrode bonds, while the 250.122 EGC sizing is for equipment bonding. The word "grounding" needs to be differentiated from bonding because of the obvious confusion.

The Equipment Grounding Conductor [250.122] has been suggested in ROP's to be renamed the Equipment 'Bonding' Conductor to emphasize Equipment Bond Fault-Safety protection to the '0' reference ac system source. The Grounding Electrode Conductor [250.66] is still referenced as being bonded to the earth embedded Grounding Electrode(s). I know...its even confusing to me sometimes.

 

[gndrod]

Metal pipe bonding

Metal pipe bonding

In reference to bonding an interior metal water pipe [250.104] bond, when in fact the incoming pipe from the well is plastic, is to bond the pipes in case of an inadvertant fault contact to any pipe[250.110]. In this case the bond serves as an EGC protection...not the grounding electrode which is non-existant in this instance. The well system EGC is still carried through to the well pump motor.

 

[Ponchik]

In reference to bonding an interior metal water pipe [250.104] bond, when in fact the incoming pipe from the well is plastic, is to bond the pipes in case of an inadvertant fault contact to any pipe[250.110]. In this case the bond serves as an EGC protection...not the grounding electrode which is non-existant in this instance. The well system EGC is still carried through to the well pump motor.

I agree with you as to why the bonding of the piping system is done. But why do you need to bond the water piping system according to 250.66 and the other piping system according to
250.122???

 

[gndrod]

egc-gec

egc-gec

I agree with you as to why the bonding of the piping system is done. But why do you need to bond the water piping system according to 250.66 and the other piping system according to
250.122???

Basically, table sizing requirements are for conductor minimum ampacity to carry a potential fault condition of the related ungrounded conductor size and overcurrent protection devices. [240.4].

 

[kwired]

Basically, table sizing requirements are for conductor minimum ampacity to carry a potential fault condition of the related ungrounded conductor size and overcurrent protection devices. [240.4].

But why is the waterpiping going to have to carry this current but other piping systems will not? Remember we are talking about water piping that has a non conductive supply and therefore is not a grounding electrode. We are supposed to size the conductor to the water piping according to 250.66 regardless of whether the piping is actually an electrode or not.

 

[michael mckague]

250.66 vs 250.120 for cold water bond

250.66 vs 250.120 for cold water bond

I was taking a shower when I thought about 250-66 vs 250-122 for bonding plumbing systems vs other metal piping. And I thought what if a ground fault happened on the plumbing when I'm in direct contact with it via the faucet while I am wet in the shower. Bonding with 250-66 helps limit voltages developed across the ground during a fault, while 250-122 helps breakers clear faults on the other metallic systems where a higher voltage across the ground can be tolerated because wet people are less likely to be in contact with it during a fault.

 

[kwired]

I was taking a shower when I thought about 250-66 vs 250-122 for bonding plumbing systems vs other metal piping. And I thought what if a ground fault happened on the plumbing when I'm in direct contact with it via the faucet while I am wet in the shower. Bonding with 250-66 helps limit voltages developed across the ground during a fault, while 250-122 helps breakers clear faults on the other metallic systems where a higher voltage across the ground can be tolerated because wet people are less likely to be in contact with it during a fault.

Unless there is something else in the shower that has earth potential but is not solidly grounded why would you ever even feel a tingle?

edit: maybe I should have said - not also bonded to same place water piping is also bonded to - like the electrical system grounding electrode system / equipment grounding conductor(s)

What I have run into in older homes that have metallic waste piping is the waste piping is not bonded and you can have potential from the water supply to the drain. Waste piping has to have ground potential otherwise it is just an isolated section of pipe, unless it is the energized component and the water supply is the object with ground potential.