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Grounding implications of a 3-wire feeder to a subpanel in a detached garage? – replace.me
replace.me › The Forums › Studio Building / Acoustics. All three wires are 4 awg. I’m aware that a 3-wire feeder without a dedicated ground used to be allowed between two detached buildings, provided.
Subpanel fed by 3 wire without EGC | Mike Holt’s Forum
The subpanel is bonded to neutral in the detached garage (definitely a no-no with a 4 wire feed, but this was built in with no dedicated. The way you have it set up a fault from hot to ground will not trip a breaker it will only feed current into one of your ground rods. Feel free. Personally I think that makes more sense than extending the neutral and grounding conductor from another building in a 4 wire feeder but they.
3-wire subpanel?? I goofed. – ECN Electrical Forums
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You should upgrade or use an alternative browser. Thread starter electrofelon Start date Feb 15, Status Not open for further replies. Ok so why do we run 4-wire instead of 3-wire to a sub panel in same structure? Well, I think I know the answer, so let me rephrase – Why is it safe to run a 3 wire to feed a service panel, but not to feed a sub panel?
George Stolz Moderator Staff member. Location Litchfield, CT. One major reason the grounded circuit conductor is NOT permitted to be grounded on the load side of the service is, should the grounded service conductor become disconnected at any point on the line side of the ground, the equipment grounding conductor and all conductive parts connected to it will carry the neutral current, raising the potential to ground of exposed metal parts not normally intended to carry current.
This could result in arcing in concealed spaces and could pose a severe shock hazard, particularly if the path is inadvertently opened by a person servicing or repairing piping or ductwork. Even without an open neutral the equipment grounding conductor path will become a parallel path with the grounded conductor, This could involve current flowing through metal building structures, piping, and ducts.
Stick, One major reason the grounded circuit conductor is NOT permitted to be grounded on the load side of the service is, should the grounded service conductor become disconnected at any point on the line side of the ground, the equipment grounding conductor and all conductive parts connected to it will carry the neutral current, raising the potential to ground of exposed metal parts not normally intended to carry current. Click to expand Thats why we BOND the neutral to the ground Last edited: Feb 15, Location Massachusetts.
Well we run a 3 wire to a service because the power company does not provide a forth wire and the NEC has no authority to make them do so. I am willing to bet that is at least part of the answer. I’d tend to agree with Bob, which probably comes as no surprise.
Ethan, my comment was more along the lines of, that is another one of your seemingly innocent questions that could result in a post thread. Keep ’em coming. Maybe the theory is that service conductors are less lkely to be compromised due to their stricter installation requirements length, wire methods, etc? Another thought: the neutral is generally larger than a required EGC would be, and would have a lower impedance during a fault. Current seeks a path back to the source. Once it has made it back to the main service panel, it has essentially achieved that goal.
What happens after that, whether the current travels along a neutral or a ground or a phase conductor, is an SEP issue. Often used as a technique for rendering electrical hazards invisible. Location Leander Texas. Ok, thats fair BUT, can’t the same thing be said of a service panel? Not fair, Jon, beating me to my own punchline. Someone Else? Credit Douglas Adams, author of the five volume trilogy that began with?
The Hitchhiker? Dirk Gently? As an example of an? SEP Field,? All around that area a field is created. The closer you are to the spot, the less comfortable you are, perhaps fearing that someone will think you are at least partially to blame. But the further you get from the spot, the more readily you can relax, knowing that the incident is? I would have considered the xfm as the source. Let’s see, what change happens at the service panel?
Why is it safe to run a 3 wire to feed a service panel, but not to feed a sub panel? When you have multiple ground-neutral bonds, you create a situation where some amount of current will flow on your ‘ground’ conductors.
However as long as your ground conductors are well bonded and have sufficient ampacity, this does not create much of a hazard. In the past and in millions of grandfathered installations, the neutral was used to bond the frame of electric ranges and dryers.
Multiple grounding of the neutral appears to have benefits in terms of protection from lightning, at least on the scale of utility distribution of power. Usually this isn’t a problem In urban areas with shared underground metallic pipes and shared utility transformers, each ‘ground to neutral’ bond in each service is in parallel with other bonds in adjacent houses. Significant current flows on the shared water pipes, and this isn’t a problem until the plumber goes to work on the pipes.
Multiple grounding of the neutral appears to cause problems when the bonding of the ground system is not sufficient. We don’t care about a 0. We care quite a bit about a 10V difference between two metal surfaces that a person could touch simultaneously. The shell of an individual structure is probably a good dividing line between permitting and prohibiting multiple grounding of the neutral.
Outside of the structure the scale of distances is such that problems will be uncommon, and the benefit of multiple grounding more important. Inside of a structure you have utilization equipment in close proximity and greater chance of touch potential, and we prohibit the such multiple bonding.
But at the boundary of the structure plumbers working on the water main and in situations sensitive over longer distances farms where metal structures can ‘focus’ potential differences , problems with multiple earth bonding can still be noticed.
But that time spent outside the house is not relevant to the safety of the person standing inside the house. It cannot shock the person, if for example the person touched a section of conduit, because it is heading towards the? Charlie, There are a few places where I’m not understanding the physics you are using. But that time the current spent outside the house is not relevant to the safety of the person standing inside the house.
What changes is that the direction of current flow is away from the house.