Joe.B
Senior Member
- Location
- Myrtletown Ca
- Occupation
- Building Inspector
Very good question and I hope somebody can answer. What's your take on it?
Please explain what you mean by a faultSay you have a house and a detached garage 10' away, supplied by a feeder from the house. The house service requires a GES. The garage requires a GES; say there are no other metallic paths between the two buildings.
So what is a scenario in which safety is greater with the garage GES in place and connected to the feeder EGC, rather than just having the single GES at the house service? E.g. a fault condition, with some postulated impedances of various paths, showing that the presence of the garage GES reduces some hazard from the fault. And which requires that the garage GES be located at the garage, rather than just being additional grounding electrodes that reduce the total GES to remote earth impedance.
If necessary, increase the 10' distance to 100' for a good example.
Cheers, Wayne
Anything other than normal operating conditions. Common ones I've heard of with respect to the GES being important are induced earth voltage from a nearby (not direct) lightning strike, or a high voltage aerial line falling on a low voltage aerial line, but I didn't want to restrict the scenarios. Let's assume the feeder from the house to the detached garage is underground, but the service to the house can be aerial.Wayne what do you mean by a fault?
This is rather misleading TomAttached is a page from the EPRI article that Mike Holt based this graphic on. This is what the OP mentions as statement #2. The article is too large to attach and I will see if I can rescan later. click on the graphic to enlarge
View attachment 2558223View attachment 2558224
iirc, that's the exact philosophy of all the nfpa 780 'lightning guys' SahibIf only auxiliary grounds and no bonding, damage due to passage of lightning current likely. If bonding also present, not likely because all points would rise to the same potential on passage of any lightning current and consequently no damaging discharges likely.
welp , now we're onto GES, which serves a different purpose that a GEC Wayne. I'm sure i'm preaching to the choir saying this , but plz cut me some slack as so many are confused......what would be an appreciable dif in 10 Vs 100' ? Mag Trip comes to mind.......~RJ~Say you have a house and a detached garage 10' away, supplied by a feeder from the house. The house service requires a GES. The garage requires a GES; say there are no other metallic paths between the two buildings.
So what is a scenario in which safety is greater with the garage GES in place and connected to the feeder EGC, rather than just having the single GES at the house service? E.g. a fault condition, with some postulated impedances of various paths, showing that the presence of the garage GES reduces some hazard from the fault. And which requires that the garage GES be located at the garage, rather than just being additional grounding electrodes that reduce the total GES to remote earth impedance.
If necessary, increase the 10' distance to 100' for a good example.
Cheers, Wayne
The EPRI article (partial) or the graphic?This is rather misleading Tom
~RJ~
You may make a more refined search for the following question:Myths and legends? Reality? Or alternate reality? Fever dreams? Need say something because they're the expert? For example:
"this connection provides a safe pathway for any excess or misdirected electrical current"
"Without grounding, electrical charges that build up in the wiring can create serious damage"
"Grounding allows excess electrical to go into the ground where it dissipates harmlessly"
"so that whenever there is a voltage surge or fluctuation, the excessive current is directed toward the ground and not through you"
"Grounding is essential to reduce the fire risk of electricity in a small space made of flammable (wood) stuff"
"One of the most important reasons for grounding electrical currents is that it protects your appliances, your home and everyone in it from surges in electricity"
"Without a properly grounded electrical system, you are risking any appliances you have connected to your system being fried beyond repair"
"Grounding helps protect you and your home from the dangers of damaged circuits or electrical overloads"
"Proper grounding is an essential component of home electrical safety because excess energy needs to be directed somewhere"
"This safety feature helps protect you and your home from electrical mishaps by running part of the electrical load into the ground"
Top 10 results when I googled "Why do houses need to be grounded."