You misrepresent my point.
Term philosophy does not refer to specific academic field, but is used in a broader sense. Looking at the origin, Greek word philosophia Philos-love and Sophia-wisdom, things become more clear.
To think that you only deal with "hard objective facts" and and in this case natural sciences without the use of philosophical inquiry is silly.
Eng.D. is a professional degree, the Ph.D. is a research degree.
Two earthed points?
Two earthed points a distance apart is not code. It is dangerous.
Here on the east coast USA we have single bushing distribution on the pole. The HV run is top of pole, return for HV is the neutral wire below the transformer, it has the 240 v pair twisted around the steel neutral for support. Every two or three poles, an earth is dropped.
As a consequence, a small percentage of the return current will be through the dirt itself, 2 to 5 percent IIRC. This forms an earth gradient, which will be picked up exactly as you measured.
Many scenarios can cause the difference to be lethal between two earthed conductors if they are a distance apart. Outside my house for example, a car dropping the utility pole could alter the earthing currents such that a large earth gradient exists.
A very significant problem with separated earths is lightning. A nearby strike will toast devices with separated earths.
PS. A distinction must be made between earthed points and bonding. Bonding is a safety thing for faults in the AC system, keeps exposed potentials low during a fault until the breaker opens. Earthing is for lightning.
Jn
Last edited:
yes it is code. New code has all signal and power lines earthed and bonded at single entry point but too late for a hundred million homes.
Two grounds isnt from the ac power wiring system alone It was/is from the CATV grounding. The CATV is/was grounded anywhere they pleased... usually at closest point to TV room and a penetration thru wall to termination type F outlet. Ditto telephone lines. These multiple grounded systems were not required to all come into home at same location as power panel.
Thus, the currents shown was not during a lightning storm. It was there continuously. If you look carefully, you will see it is a CATV coax current flow when CATV is connected to equipment where power is grounded else where.
-RNM
Two grounds isnt from the ac power wiring system alone It was/is from the CATV grounding. The CATV is/was grounded anywhere they pleased... usually at closest point to TV room and a penetration thru wall to termination type F outlet. Ditto telephone lines. These multiple grounded systems were not required to all come into home at same location as power panel.
Thus, the currents shown was not during a lightning storm. It was there continuously. If you look carefully, you will see it is a CATV coax current flow when CATV is connected to equipment where power is grounded else where.
-RNM
Last edited:
Ah, you speak of residences where cable and telephone may not enter the house at the same location as the primary AC feed.. It is indeed legacy, a design Martzloff called an upside down house.
In those cases, the second earthing conductor is not functioning as the AC power feed earth, but for the utility.
That is why I always recommend any system using AC as well as another wire link to the outside world such as cable, use a multiport SPD at the point of use.
Jn
JN.
Much too complicated for a casual consumer who just wants that hum/buzz they got when they bought and installed a TV/Video and audio system together.
Besides all the benefits of separate. isolated filters, in the same chassis of all Monster products was the F-type cable which provided transient protection but also grounding to ac power and all gear connected had that chassis as common ground point. no current loops between connected equipment.
(note phone grnd and protection, also)
Its a well researched product. Thoroughly designed and built. The oem manufacture called me and told me they have found about 20 NOS they are going to sell from their warehouse.
THx-RNMarsh
Much too complicated for a casual consumer who just wants that hum/buzz they got when they bought and installed a TV/Video and audio system together.
Besides all the benefits of separate. isolated filters, in the same chassis of all Monster products was the F-type cable which provided transient protection but also grounding to ac power and all gear connected had that chassis as common ground point. no current loops between connected equipment.
(note phone grnd and protection, also)
Its a well researched product. Thoroughly designed and built. The oem manufacture called me and told me they have found about 20 NOS they are going to sell from their warehouse.
THx-RNMarsh
Last edited:
Killing earth gradients.
1974, installing and testing new hardware to receive digital pictures from SMS ( Synchronous Meteorological Satellite ) I had a scope plugged on a nearby socket. I had another equipment plugged elsewhere far in the same room....Nothing was working as expected, then I unplugged a BNC cable with my right hand, with my left hand on the chassis of this grounded equipment, as soon as the BNC got off I got a violent electric shock through me. Thankfully all jerked away, after recovering then cursing, I was told they had recently did wiring works in the building.
Well, since then I will never trust two grounds are ground.
The theory, yes. But the practice of using a multiport SPD is not. It is a turnkey device, requiring no understanding of maxwell's equations, code, nuttin.
Jn
essentially that is what is on the rear panel.
https://www.erico.com/catalog/literature/TNCR022.pdf
THx-RNMarsh
Last week we got an alert on some (Edit: IEC line cords..EIC is electron ion collider) line cords. Seems that some had ground and HOT swapped, putting chassis at 120 volts.
And apparently they were marked as listed in Canada and the USA.
This is not the first I've seen of this either, it happened a few years ago.
If a cord of this nature were used for a preamp, with the amp cord correct, the act of plugging the power first then IC's could result in electrocution. This is why I bond all external metal surfaces (it's code actually), and never try to break a ground loop with a resistor, diode, or inductor.
Oh, and silly me...I always measure a new cord for ground continuity.
Jn
Ed: the Seattle Police Department is the NEC enforcement branch. They used to work out of sector seven, but once the all-spark was gone, they needed something to do..
Pps. For those sick and tired of the acronyms...multiport Surge Protection Device has surge protection for line voltage as well as cable/phone/internet. And, it ties all the grounds. For RM's measurement, the current would not flow through the IC's, but are diverted before reaching the equipment.
Also, the induced voltages caused by a nearby strike will not fry all the equipment inputs or outputs. When strike induced voltages reach a kv per square meter, and the ground loop area is the size of the house...you get the picture.
And apparently they were marked as listed in Canada and the USA.
This is not the first I've seen of this either, it happened a few years ago.
If a cord of this nature were used for a preamp, with the amp cord correct, the act of plugging the power first then IC's could result in electrocution. This is why I bond all external metal surfaces (it's code actually), and never try to break a ground loop with a resistor, diode, or inductor.
Oh, and silly me...I always measure a new cord for ground continuity.
Jn
Ed: the Seattle Police Department is the NEC enforcement branch. They used to work out of sector seven, but once the all-spark was gone, they needed something to do..
Pps. For those sick and tired of the acronyms...multiport Surge Protection Device has surge protection for line voltage as well as cable/phone/internet. And, it ties all the grounds. For RM's measurement, the current would not flow through the IC's, but are diverted before reaching the equipment.
Also, the induced voltages caused by a nearby strike will not fry all the equipment inputs or outputs. When strike induced voltages reach a kv per square meter, and the ground loop area is the size of the house...you get the picture.
Last edited:
Ground pin Not connected.
An amazing news: This is legal in France for some house sockets and it is done frequently.
First of all we have bureaucrats that change rules and regulations so many often that it becomes near impossible to maintain electric wiring.
So it became allowed to keep old wiring as of its installation date. Of course any new stuff must comply to the latest rules.
It is quite common to have apartments where the rules were sockets in "wet rooms" ( kitchen, bathroom ) have 3 prongs sockets while other rooms ( living, bedrooms,,, ) have 2 prongs sockets, no ground wire.
When such a 2 prong socket needs replacement electricians put 3 prong sockets and of course there is no wire to connect the ground prong. They say it's legal...Of course nobody wants to stock 2 prong sockets and they became more expensive.
I consider this is a murder attempt and do want two prongs where there is no ground wire.
They think, I am nut and I do not care.
Fortunately there is a rule that makes sense: All the in house wiring must be protected by 20mA differential breakers. Next, all circuits must be protected by breakers of a rate according to the wire section, this is usually misunderstood; It is not there to protect people, it protects the wires from overheating that might induce a fire start. Next there all sorts of silly rules of various kinds that make house mods puzzling nightmares.
An amazing news: This is legal in France for some house sockets and it is done frequently.
First of all we have bureaucrats that change rules and regulations so many often that it becomes near impossible to maintain electric wiring.
So it became allowed to keep old wiring as of its installation date. Of course any new stuff must comply to the latest rules.
It is quite common to have apartments where the rules were sockets in "wet rooms" ( kitchen, bathroom ) have 3 prongs sockets while other rooms ( living, bedrooms,,, ) have 2 prongs sockets, no ground wire.
When such a 2 prong socket needs replacement electricians put 3 prong sockets and of course there is no wire to connect the ground prong. They say it's legal...Of course nobody wants to stock 2 prong sockets and they became more expensive.
I consider this is a murder attempt and do want two prongs where there is no ground wire.
They think, I am nut and I do not care.
Fortunately there is a rule that makes sense: All the in house wiring must be protected by 20mA differential breakers. Next, all circuits must be protected by breakers of a rate according to the wire section, this is usually misunderstood; It is not there to protect people, it protects the wires from overheating that might induce a fire start. Next there all sorts of silly rules of various kinds that make house mods puzzling nightmares.
The design of the UK wall plug may be an example to the rest of the world. Why Britain Has The Best Wall Sockets On Earth
What NEC Article would that be?
* * * * * * * * *
Or is that leakage from Neutral to Safety Ground?
Last edited:
Terrible. I’d be pretty unhappy if that were the case where I live. I never understood US wiring though where IIUC you mix up Ground and Neutral.
This is not a dig - please correct me if I’m wrong. How the hell can you have 15 mA flowing in a ground unless there is a fault?
The US being a big place uses hot conductors normally three phase to distribute power. In the eastern part of the US one of the high voltage phases is connected to a local residential distribution auto-transformer this in my neighborhood steps down 13,600 volts to 126-0-126 VAC. The 0 volt line is called the neutral and is grounded usually at each local drop transformer and at the building entrance.
Note the neutral is also required to handle the current from the high voltage distribution line. As each residence draws current the is some voltage drop along every length of wire. So if you measure from one power drop's ground connection to another there will be a potential difference. If you drive a secondary ground rod for a service such as cable TV in between two power ground rods it is easy to have a potential voltage between any combination of ground rods.
The idea was to save one conductor in the long distance power lines.
Some local utilities run the neutral or grounded conductor on the top of the power lines to reduce lightning damage. Others may run it lower. As a result there are lightning strikes that only damage half of the connected devices in some locations. In others everything gets damaged, but it does take more of a surge. (A lot of half damaged users vs a few totally blown!)
The safety ground is a different conductor and is connected to the same building neutral ground at one location only.
Last edited:
Obviously neutrals that are carrying current will have different voltage potentials at their receptacles. The safety grounds at different receptacles can have different potentials also. If you have two pieces of gear connected to different receptacles with the chasses connected to the safety ground at different outlets you can have a potential difference. As JN mentioned this is an inductive coupling. Ground fault circuit interrupters do have minimum trip currents because quite simply the hot and neutral current may not match exactly. They do need to trip at current levels that are harmful.
Thanks. A lot. We are not all, here, members of the same US private club.
- Status
- Not open for further replies.