archibald tuttle
Member
so thinking about everything i've learned by reading other threads in the Grounding vs. bonding subforum, the bonding is meant to ensure tripping breakers when a hot to EGC fault occurs as otherwise the impedance of the earth ground might not pass enough amperage to trip the breaker leaving the entire ground network with dangerous potential.
makes sense so far as it goes.
so presumably bonding the metal water system is meant to insure a similar result in case of some less likely but not impossible accident that results in a hot wire contacting the water system that the breaker is tripped.
however grounding the water system creates multiple likely sources of NEV nuisance. my nieces and nephews discovered what the cows have known for years during a water ballon war yesterday.
now i finished a legion set of posts and replies on NEV problems with drinking water trough heaters and ultimately only solved my own 7 to 9 volt problem by cutting the third prong off the trough heater.
of course the trough heater is on a GFCI so i have primary protection against currents smaller than the trip current going AWOL. While I have seldom seen it, the various studies on GFCI field performance referenced here do indicate that there is some percentage of failure on vs. failure off (meaning that my small real world sampling that has only experienced failure off would be the wrong indicator of whether this is anything to worry about). so this arrangement is not without any risk, but compared to the horses not drinking they can colic and die from that long before they encounter a failed on GFCI and a failure of insulation on the heater conducters or heater itself at the same time.
so, this one isolated circumstance of depending on the GFCI for low amperage fault protection on a rural property seemed kind of like the common sense approach. But now that i am sensitized to the issue, i'm measuring these NEVs as 5 to 7 volts in many urban installations. probably, like our roads, our electric infrastructure is vastly undersized. But the price of metal and bureaucracy lately suggests to me that we are going to be putting much more money in 'smart' meters than into smart investments such as improving infrastructure. So this NEV issues is starting to look pretty global (in the national sense that is) to me. As i start to realize the number of instances of NEV current being transmitted to people, me regularly in construction work where water and electricity mix, e.g. concrete cutting and drilling, as well as the more recreational instance describe above of filling water ballons, it occurs to me that, for the sake of preventing the unlikely transmission of higher voltage accidentally, we are essentially insuring the non-accidental delivery of lower voltage. Now the unlikely voltage is potentially lethal while the non-accidental voltage is largely a nuisance although it has proven to be a productivity problem in animal husbandry. so i'm not making an up front cost benefit case. but the unintended consequence of not considering reducing NETPV (i.e. Netural to Earth Through People Voltage) is that folks will start to look for ways around it that might create other hazards they cannot assess.
Given that we have gone so far down the line with an infrastructure that does not isolate the line loss in the primary voltage from the user of the secondary voltage and that primary wiring carrying capacity does not appear to have kept pace with the increase in use, hence the many instances i have experienced of NETPV in both rural, suburban and urban settings I'm thinking some more practical mitigation might be appropriate. I wonder at some juncture since there is pressure, about which i'm ambivalent, for more and more GFCI coverage, whether outfitting with all GFCI breakers for a structure could present an option for foregoing bonding -- at least of water systems. i tend to think it more likely you could accidentally energize the metal enclosure or EGC system.
respectfully submitted,
perplexed (and lightly shocked) in Rhode Island
makes sense so far as it goes.
so presumably bonding the metal water system is meant to insure a similar result in case of some less likely but not impossible accident that results in a hot wire contacting the water system that the breaker is tripped.
however grounding the water system creates multiple likely sources of NEV nuisance. my nieces and nephews discovered what the cows have known for years during a water ballon war yesterday.
now i finished a legion set of posts and replies on NEV problems with drinking water trough heaters and ultimately only solved my own 7 to 9 volt problem by cutting the third prong off the trough heater.
of course the trough heater is on a GFCI so i have primary protection against currents smaller than the trip current going AWOL. While I have seldom seen it, the various studies on GFCI field performance referenced here do indicate that there is some percentage of failure on vs. failure off (meaning that my small real world sampling that has only experienced failure off would be the wrong indicator of whether this is anything to worry about). so this arrangement is not without any risk, but compared to the horses not drinking they can colic and die from that long before they encounter a failed on GFCI and a failure of insulation on the heater conducters or heater itself at the same time.
so, this one isolated circumstance of depending on the GFCI for low amperage fault protection on a rural property seemed kind of like the common sense approach. But now that i am sensitized to the issue, i'm measuring these NEVs as 5 to 7 volts in many urban installations. probably, like our roads, our electric infrastructure is vastly undersized. But the price of metal and bureaucracy lately suggests to me that we are going to be putting much more money in 'smart' meters than into smart investments such as improving infrastructure. So this NEV issues is starting to look pretty global (in the national sense that is) to me. As i start to realize the number of instances of NEV current being transmitted to people, me regularly in construction work where water and electricity mix, e.g. concrete cutting and drilling, as well as the more recreational instance describe above of filling water ballons, it occurs to me that, for the sake of preventing the unlikely transmission of higher voltage accidentally, we are essentially insuring the non-accidental delivery of lower voltage. Now the unlikely voltage is potentially lethal while the non-accidental voltage is largely a nuisance although it has proven to be a productivity problem in animal husbandry. so i'm not making an up front cost benefit case. but the unintended consequence of not considering reducing NETPV (i.e. Netural to Earth Through People Voltage) is that folks will start to look for ways around it that might create other hazards they cannot assess.
Given that we have gone so far down the line with an infrastructure that does not isolate the line loss in the primary voltage from the user of the secondary voltage and that primary wiring carrying capacity does not appear to have kept pace with the increase in use, hence the many instances i have experienced of NETPV in both rural, suburban and urban settings I'm thinking some more practical mitigation might be appropriate. I wonder at some juncture since there is pressure, about which i'm ambivalent, for more and more GFCI coverage, whether outfitting with all GFCI breakers for a structure could present an option for foregoing bonding -- at least of water systems. i tend to think it more likely you could accidentally energize the metal enclosure or EGC system.
respectfully submitted,
perplexed (and lightly shocked) in Rhode Island
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