Good afternoon! I have a customer who has complained about being shocked when they turned on the spigot outside. Sure enough, I am reading anywhere between .4 volts - 1.5 volts. Of course, I can't feel that. Nonetheless, there is voltage. Maybe more at times. I don't know.
Upon further inspection I discovered that the two subpanels inside the building have the neutrals and grounds bonded together. I thought, "A-ha! I either have a neutral backfeeding that voltage to the cold water ground or I have a ground loop." Then I discover that there is no grounding system whatsoever. Unless there is a uffer (slab ground) in the meter can, there is nothing, and no cold water ground that I can find.
So, next decided to go ahead and separate all grounds and neutrals in the subpanels. I ran appropriately sized EGCs to both subpanels, ran a ground from the hose bib to the service, and drove a ground rod. At some point during all of this, I checked for voltage between one of the subpanel EGCs and a ground on a branck circuit (I actually checked three different branch circuit grounds, and one of those was a multi wire branch circuit that I ran the day before). I was reading 40-55 volts to ground on each of those grounds. The thing is, though, is that whoever wired this building cut most of the grounds on the load end. What a mess.
Anyway. I continued with the grounding of the service and subpanels kind of hoping that it would go away or fix itself. I finished with grounding all of the service equipment/panels. I'm not getting that 40-50Volts anymore, but, I still have the .4- 1.5 Volts on the water lines. The only time it goes away is when I open the main disconnect breaker. I have also tested the messenger wire from the utility transformer to my ground rod and I get nothing. I am rebuilding the service tomorrow, and I'm hoping that will shed some light on what is happening.
Any thoughts on what is happening here? I'm perplexed with the .4-1.5 volts and totally blown away with the 40-50V reading on the branch circuit grounds. Thanks for any helpful input. Or otherwise.
Upon further inspection I discovered that the two subpanels inside the building have the neutrals and grounds bonded together. I thought, "A-ha! I either have a neutral backfeeding that voltage to the cold water ground or I have a ground loop." Then I discover that there is no grounding system whatsoever. Unless there is a uffer (slab ground) in the meter can, there is nothing, and no cold water ground that I can find.
So, next decided to go ahead and separate all grounds and neutrals in the subpanels. I ran appropriately sized EGCs to both subpanels, ran a ground from the hose bib to the service, and drove a ground rod. At some point during all of this, I checked for voltage between one of the subpanel EGCs and a ground on a branck circuit (I actually checked three different branch circuit grounds, and one of those was a multi wire branch circuit that I ran the day before). I was reading 40-55 volts to ground on each of those grounds. The thing is, though, is that whoever wired this building cut most of the grounds on the load end. What a mess.
Anyway. I continued with the grounding of the service and subpanels kind of hoping that it would go away or fix itself. I finished with grounding all of the service equipment/panels. I'm not getting that 40-50Volts anymore, but, I still have the .4- 1.5 Volts on the water lines. The only time it goes away is when I open the main disconnect breaker. I have also tested the messenger wire from the utility transformer to my ground rod and I get nothing. I am rebuilding the service tomorrow, and I'm hoping that will shed some light on what is happening.
Any thoughts on what is happening here? I'm perplexed with the .4-1.5 volts and totally blown away with the 40-50V reading on the branch circuit grounds. Thanks for any helpful input. Or otherwise.
