Open Service Neutral GFCI/RCD Detector

[mbrooke]

This is the situation why we can't add a third grounding wire to service entrance:

My parent house is part of a 5 house compound (called townhouses). The utility service entrance is outside the red gate. There are 2 houses between the utility and my parent house which is at the back. Our feeder is under the driveway. We need to demolish the driveway just to access the feeder and wires. Distance to front is 35 meters.

This is our service entrance panels outside the compound in the street:​

You can see the feeder is small. And it is about 35-40 meters to the house main panel crossing many bends under the driveway. If we pull it out. We can no longer put a new 3 wire inside because the feeder is corroded and rusty (they put the wires at every angle during construction before driveway was concreted).

So how do you propose we replace 40 meters of new wires under the driveway (or even adding just the ground wire)? The neighbors won't allow. They don't want any power interruption or not able to use the driveway during the repair or destroying it (the new concrete won't blend with old one). They don't use any ground wire just like millions and since nothing happens to them. They thought it was superfluous. And lastly, they don't want my parent 40 meters wires and new feeder to hang on their driveway.
​

So the only sound solution is 100A RCD (30mA) just to protect the Siemens subpanel. All the appliances in the homes will be protected by GFCIs. Hence pls. give me the most advanced RCD model in the planet, perhaps one you can even monitor with smartphone

No conduit?

 

[kwired]

Canada calls it a bonding conductor. UK circuit protective conductor. Much more well defined.

What do they call the grounded service conductor and the grounding electrode conductor, and maybe other current carrying grounded conductors? NEC does have a different term for each, just happens to have that root word "ground" in more than one of the terms, and people see that and think they all mean the same thing.

 

[mbrooke]

What do they call the grounded service conductor

PEN (protective earthed neutral) or MEN (multiply earthed neutral) in a TN-C-S supply, neutral and protective in TN-S.

and the grounding electrode conductor, and maybe other current carrying grounded conductors?

This:

NEC does have a different term for each, just happens to have that root word "ground" in more than one of the terms, and people see that and think they all mean the same thing.

Wrong root to use for the purpose it serves. Grounded in terms of a corner grounded delta phase or leg of a 2 wire supply; and grounding in terms of connecting to an earthing electrode are the only correct applications pf that root IMO.

 

[tersh]

well.. wonder about the solution some have here of grounding one of the two live wires... not sure if it works or not but... if it worked and created a UK style 240 volt system..well...
I dont have the guts or the knowledge to try it, however.

I'm sure the utility won't transfer their ground to one of the two live wires. This is because what's the point when most homes don't bother with grounding. This can produce a nightmare scenario when local electricians who just used to wire 2 lines randomly without any bonding requirement would need to bond one of the lives. What if they connect the house EGC to the other ungrounded hot wire, then it's like all metal chassis at house become 240v potential with respect to the utility grounded other hot. This can produce dozens of electrocutions a single day or worse. By the way, right now, all their (utility) poles have grounded centertap (connected to pole ground rod). It's not floating.

mbrooke, here's the conduit:

Who are familiar with RCD without electronics. I'd like to know the following:

1. What components can usually breakdown for RCDs without electronics?
2. For TT homes in Europe where they put RCD/RCBO for main breaker/disconnect, how often the RCD/RCBO (without electronics) become defective and how does this compare to regular breaker in terms of reliability or lifetime?
3. If you replace regular breakers with RCBO. Is the lifetime the same?
4. What is better in terms of robustness or resistant to failure.. when you use RCDs with regular main breaker or use combined RCBO (Residual Current Circuit Breaker with Over current) device?
5. 150mA tripping RCD would be more resistance to nuisance tripping right? But do some still have nuisance tripping for 150mA?

I'm referring to RCD/RCBO without electronics only in all the questions above?

 

[tersh]

What do they call the grounded service conductor and the grounding electrode conductor, and maybe other current carrying grounded conductors? NEC does have a different term for each, just happens to have that root word "ground" in more than one of the terms, and people see that and think they all mean the same thing.

In communicating with you guys. I'll use the NEC terminology.

So Equipment Grounding Conductors (EGC) refers to all the wires from metal chassis straight to the utility transformer centertap.
Grounding Electrode Conductor (GEC) refers to the 10 feet ground rod you stuck at soil distance 6 feet apart.

I don't have either in my parents home. But in my office building we both have EGC and GEC.. this is where the Siemens First Surge is connected to in earlier image.

By the way. In my parents house, the following is the condition of the ground wire from utility centertap (I didn't mentioned neutral wire because let's reserve the term neutral wire to be used only if utility meant it to be used as 120v. If not, then just ground wire).

\


In most residences, the utility centertap ground wire (neutral in your terminology) is mostly left hanging at the service entrance (shown in blue arrow). Contractors are all into cost cutting so didn't add the third ground wire to house since our appliances have no grounding. Even in my office building, contractor only insert third ground wire up to panel only. But panels to all the outlets/receptacles have no ground wire and all 2 prong outlets only.

Now notice the ground wire/neutral at middle picture hanging by a thread only. In the event there is ground fault at any chassis at home and EGC fully in place, it may not trip breaker because of resistances of small AWG wire that may not reach the 10X ampere threshold of the breaker.

So we need to let the utility repair their ground wire at service entrance.

But here's the problems. Since homes never use the ground wire at service entrance. It's always badly maintained. What if one day during some utility work, they accidentally connected the ground wire to hot. Since no one else in the neighbor have any EGC. They won't feel a thing. But I'd have 240v hot potential now in my panel metal chassis. This is the danger when only one person out of 100,000 installed EGC. That is why RCDs with GEC (to at least reach 500mA) is the safest, ain't it?

 

[ptonsparky]

In communicating with you guys. I'll use the NEC terminology.

So Equipment Grounding Conductors (EGC) refers to all the wires from metal chassis straight to the utility transformer centertap.
Grounding Electrode Conductor (GEC) refers to the 10 feet ground rod you stuck at soil distance 6 feet apart.

I don't have either in my parents home. But in my office building we both have EGC and GEC.. this is where the Siemens First Surge is connected to in earlier image.

By the way. In my parents house, the following is the condition of the ground wire from utility centertap (I didn't mentioned neutral wire because let's reserve the term neutral wire to be used only if utility meant it to be used as 120v. If not, then just ground wire).

\


In most residences, the utility centertap ground wire (neutral in your terminology) is mostly left hanging at the service entrance (shown in blue arrow). Contractors are all into cost cutting so didn't add the third ground wire to house since our appliances have no grounding. Even in my office building, contractor only insert third ground wire up to panel only. But panels to all the outlets/receptacles have no ground wire and all 2 prong outlets only.

Now notice the ground wire/neutral at middle picture hanging by a thread only. In the event there is ground fault at any chassis at home and EGC fully in place, it may not trip breaker because of resistances of small AWG wire that may not reach the 10X ampere threshold of the breaker.

So we need to let the utility repair their ground wire at service entrance.

But here's the problems. Since homes never use the ground wire at service entrance. It's always badly maintained. What if one day during some utility work, they accidentally connected the ground wire to hot. Since no one else in the neighbor have any EGC. They won't feel a thing. But I'd have 240v hot potential now in my panel metal chassis. This is the danger when only one person out of 100,000 installed EGC. That is why RCDs with GEC (to at least reach 500mA) is the safest, ain't it?

it is really difficult to prevent ‘what ifs’ especially with the circumstances you are dealing with.

 

[mbrooke]

Who are familiar with RCD without electronics. I'd like to know the following:

1. What components can usually breakdown for RCDs without electronics?

The mechanical components can jam.

2. For TT homes in Europe where they put RCD/RCBO for main breaker/disconnect, how often the RCD/RCBO (without electronics) become defective and how does this compare to regular breaker in terms of reliability or lifetime?

Not sure- but I do know that in the US the failure rate gets high as GFCIs age.

3. If you replace regular breakers with RCBO. Is the lifetime the same?

Not 100% sure.

4. What is better in terms of robustness or resistant to failure.. when you use RCDs with regular main breaker or use combined RCBO (Residual Current Circuit Breaker with Over current) device?

Honestly, I'd go with an RCD, some RCBOs have electronics that I know of. RCBOs without electronics would be about the same in my book.

5. 150mA tripping RCD would be more resistance to nuisance tripping right? But do some still have nuisance tripping for 150mA?

It would be more resistant to nusinance tripping. Whether that will take place depends on the amount of leakage current on the system.

Do you have more details about the system you are trying to protect?

 

[tersh]

The mechanical components can jam.




Not sure- but I do know that in the US the failure rate gets high as GFCIs age.




Not 100% sure.



Honestly, I'd go with an RCD, some RCBOs have electronics that I know of. RCBOs without electronics would be about the same in my book.




It would be more resistant to nusinance tripping. Whether that will take place depends on the amount of leakage current on the system.

Do you have more details about the system you are trying to protect?

System is just typical home 3 bedrooms and 2-storey.. I need to first get a leakage current meter (sensitive clamp meter and reliable model but not as expensive as the $707 Fluke 360 series) where it can record the leakage of refrigerator over days and save in memory and plot it. Meanwhile. I'll accompany my parents to vacation in the countryside tomorrow for a week so will analyze all these stuff when I return. Also still awaiting words from Siemens if the following is ballpark or not and whether it's counterfeat breakers. Do you know there are too many counterfeit breakers out there (google "counterfeit breakers) and if genuine manufacturers can issue mass (millions of units) recall such as the following:

https://www.cpsc.gov/Recalls/2010/siemens-recalls-circuit-breakers-due-to-fire-hazard

"WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission, in cooperation with the firm named below, today announced a voluntary recall of the following consumer product. Consumers should stop using recalled products immediately unless otherwise instructed. It is illegal to resell or attempt to resell a recalled consumer product.
Name of Product: Siemens and Murray Circuit Breakers, Load Centers and Meter Combos
Units: About 2.2 million
Importer: Siemens Industry Inc., of Alpharetta, Ga.
Hazard: The recalled circuit breakers have a spring clip that can break during normal use, leading to a loss of force to maintain a proper electrical connection in the panelboard. This can lead to excessive temperature, arcing or thermal damage at the connection point, and damage to the panelboard's electrical insulation and can result in a fire, property damage, or personal injury.
Incidents/Injuries: Siemens has received one report of a circuit breaker spring clip that broke during installation. No injuries have been reported."

One report is enough to make Siemens issue recall. So if Siemens has heard of other people with GFCI that burns the panel. Then they would issue recall. Siemens told me their engineering will test the following issue soon (someone told me the contacts should be flat and no gap.. so I wonder whether gap is allowed as toleraances). I need to wait so I won't have to hire the most skilled electrician twice (to install them and then remove them).. Meantime. Have a merry Christmas everyone! Thanks for all the assistances. I'm still trying to understand all the different grounding systems in different parts of the world. TN-S, TN-C, TN-C-S, TT, IT, etc. We only talked about US and Europe. I wonder what systems Russia and China use.


​

 

[Tony S]

Mechanical parts are a problem with any type of circuit breaker. If it’s proposed to locate something along the lines of an RCBO outdoors as in the picture I wouldn’t give any guarantee of it working when needed.

RCD’s of 100/300/500mA are available, my first house had a 500mA unit. For a 30mA unit I’d have to sell the new wife to pay for it.

Looking at the location picture it should be possible to drill through the paving and then sink an earth electrode.

 

[kwired]

PEN (protective earthed neutral) or MEN (multiply earthed neutral) in a TN-C-S supply, neutral and protective in TN-S.




This:

Wrong root to use for the purpose it serves. Grounded in terms of a corner grounded delta phase or leg of a 2 wire supply; and grounding in terms of connecting to an earthing electrode are the only correct applications pf that root IMO.

Name them what you want, they all tie together at some point, people will always misunderstand what the true function of certain components of this network are all about.

Then complicate it even more by attaching a normally current carrying conductor to said network such as a typical neutral conductor.

 

[mbrooke]

Name them what you want, they all tie together at some point, people will always misunderstand what the true function of certain components of this network are all about.

Then complicate it even more by attaching a normally current carrying conductor to said network such as a typical neutral conductor.

Why not name it by the correct definition? Can we just admit that at some point in time the code actually thought the soil aided in shock prevention and clearing faults?

 

[kwired]

In communicating with you guys. I'll use the NEC terminology.

So Equipment Grounding Conductors (EGC) refers to all the wires from metal chassis straight to the utility transformer centertap.
Grounding Electrode Conductor (GEC) refers to the 10 feet ground rod you stuck at soil distance 6 feet apart.

I don't have either in my parents home. But in my office building we both have EGC and GEC.. this is where the Siemens First Surge is connected to in earlier image.

By the way. In my parents house, the following is the condition of the ground wire from utility centertap (I didn't mentioned neutral wire because let's reserve the term neutral wire to be used only if utility meant it to be used as 120v. If not, then just ground wire).

\


In most residences, the utility centertap ground wire (neutral in your terminology) is mostly left hanging at the service entrance (shown in blue arrow). Contractors are all into cost cutting so didn't add the third ground wire to house since our appliances have no grounding. Even in my office building, contractor only insert third ground wire up to panel only. But panels to all the outlets/receptacles have no ground wire and all 2 prong outlets only.

Now notice the ground wire/neutral at middle picture hanging by a thread only. In the event there is ground fault at any chassis at home and EGC fully in place, it may not trip breaker because of resistances of small AWG wire that may not reach the 10X ampere threshold of the breaker.

So we need to let the utility repair their ground wire at service entrance.

But here's the problems. Since homes never use the ground wire at service entrance. It's always badly maintained. What if one day during some utility work, they accidentally connected the ground wire to hot. Since no one else in the neighbor have any EGC. They won't feel a thing. But I'd have 240v hot potential now in my panel metal chassis. This is the danger when only one person out of 100,000 installed EGC. That is why RCDs with GEC (to at least reach 500mA) is the safest, ain't it?

EGC starts at main/system bonding jumper and bonds all non current carrying components of the electrical system. It is only intended to carry current during abnormal conditions

Center tap of transformer is neutral of that winding even if it isn't connected to anything at all.

Directional boring methods could cross that driveway without destruction of it. What you going to do if existing conductor ever fails under that driveway?

 

[kwired]

But here's the problems. Since homes never use the ground wire at service entrance. It's always badly maintained. What if one day during some utility work, they accidentally connected the ground wire to hot. Since no one else in the neighbor have any EGC. They won't feel a thing. But I'd have 240v hot potential now in my panel metal chassis. This is the danger when only one person out of 100,000 installed EGC. That is why RCDs with GEC (to at least reach 500mA) is the safest, ain't it?

If they lifted the neutral connection and grounded one end right now, (presuming nobody has anything connected to neutral) it won't hurt a thing, considering how messed up it already is. Everyone will have a grounded conductor brought into their place that they could choose to bond to non current carrying components, but would still need to run additional bonding conductors beyond their service equipment and install grounding electrodes at the service equipment to have it done like NEC would want it done.

If POCO made such change to grounding point and users left things as you described, everything still would work as is, just one conductor is now at ground potential and the other conductor is now 240 volts to ground.

 

[tersh]

If they lifted the neutral connection and grounded one end right now, (presuming nobody has anything connected to neutral) it won't hurt a thing, considering how messed up it already is. Everyone will have a grounded conductor brought into their place that they could choose to bond to non current carrying components, but would still need to run additional bonding conductors beyond their service equipment and install grounding electrodes at the service equipment to have it done like NEC would want it done.

If POCO made such change to grounding point and users left things as you described, everything still would work as is, just one conductor is now at ground potential and the other conductor is now 240 volts to ground.

On January 2 after my return from vacation, I'll bring this up to the utility company if they can do the above. But I need to understand the behavior of mixed pole grounding.

Supposed the utility company do it to the pole in front of the townhouse. Remove the neutral ground and transfer the ground to one of the hots (I understood the concept as an EE emphasized I must ground one of the hots of the 500va step down isolation transformer to suppress common mode surge). But supposed the utility company do it only to our pole, and the other poles nearby still has grounded centertap neutral. In other words, for mixed neutral poles together in one street, would this induce current between the pole with ground at one hot and and the nearby poles with ground at centertap? What would be the voltage gradients (would this be induced?) in the ground between the two mixed poles. Would current flow between them? What is Mike Holt comment about mixed neutral poles together in one street or one area? Please share what he thought. I need to thoroughly understand this behavior before even talking to the utility power company next year. Thanks.

 

[kwired]

On January 2 after my return from vacation, I'll bring this up to the utility company if they can do the above. But I need to understand the behavior of mixed pole grounding.

Supposed the utility company do it to the pole in front of the townhouse. Remove the neutral ground and transfer the ground to one of the hots (I understood the concept as an EE emphasized I must ground one of the hots of the 500va step down isolation transformer to suppress common mode surge). But supposed the utility company do it only to our pole, and the other poles nearby still has grounded centertap neutral. In other words, for mixed neutral poles together in one street, would this induce current between the pole with ground at one hot and and the nearby poles with ground at centertap? What would be the voltage gradients (would this be induced?) in the ground between the two mixed poles. Would current flow between them? What is Mike Holt comment about mixed neutral poles together in one street or one area? Please share what he thought. I need to thoroughly understand this behavior before even talking to the utility power company next year. Thanks.

Each transformer secondary is an independent system, you can ground any terminal of the secondary and other secondaries won't care.

That said if POCO standard practice is to ground the center tap - you probably aren't going to get what you want.

bottom line here is utility and utilization never aligned themselves with one another in any way.

 

[tersh]

On January 2 after my return from vacation, I'll bring this up to the utility company if they can do the above. But I need to understand the behavior of mixed pole grounding.

Supposed the utility company do it to the pole in front of the townhouse. Remove the neutral ground and transfer the ground to one of the hots (I understood the concept as an EE emphasized I must ground one of the hots of the 500va step down isolation transformer to suppress common mode surge). But supposed the utility company do it only to our pole, and the other poles nearby still has grounded centertap neutral. In other words, for mixed neutral poles together in one street, would this induce current between the pole with ground at one hot and and the nearby poles with ground at centertap? What would be the voltage gradients (would this be induced?) in the ground between the two mixed poles. Would current flow between them? What is Mike Holt comment about mixed neutral poles together in one street or one area? Please share what he thought. I need to thoroughly understand this behavior before even talking to the utility power company next year. Thanks.

To add to the scenario questions, what is the voltage gradients meters away from our GEC or house, would it just feel the pole grounded hot leg in front of the compound or would the GEC also feel the other pole grounded neutral nearby? And what is the behavior of the interaction. I want to plot the voltage gradients.

Usually how many distance furthest before the GEC and house soil can still feel the utility ground rods? 30 meters? 50 meters? 300 meters? What is the figure?

 

[kwired]

To add to the scenario questions, what is the voltage gradients meters away from our GEC or house, would it just feel the pole grounded hot leg in front of the compound or would the GEC also feel the other pole grounded neutral nearby? And what is the behavior of the interaction. I want to plot the voltage gradients.

Usually how many distance furthest before the GEC and house soil can still feel the utility ground rods? 30 meters? 50 meters? 300 meters? What is the figure?

Under 1000 volts voltage zones around a grounding electrodes drop pretty rapidly. If you are only 5 feet away from the electrode you are likely pretty near true earth voltage, especially with only 120 volts on the electrode.

 

[ptonsparky]

Under 1000 volts voltage zones around a grounding electrodes drop pretty rapidly. If you are only 5 feet away from the electrode you are likely pretty near true earth voltage, especially with only 120 volts on the electrode.

The ground rod test I had a few months ago at the school ball field disagrees. I had well over 100 volts at 6’ in reference to the rod.

 

[tersh]

Let me post this last drawing before I got to an island called Batanes later which may not have internet.

First I know that "Current doesn't go to ground. It leaves source and return to source" as Mike put it. The soil is just a conductor. Therefore my GEC and home soil won't feel any current from other poles but the one it is directly connected to, right?

I'd like to clarify the voltage gradient shown in Mike's video and others. Supposed the utility pole is outside the red gate and the centertap is grounded (which really is now), Is this correct?

So the nearer it is to utility ground rod, the bigger is the voltage at the ground?
The nearer to the GEC the less is the voltage? (GEC = Grounding Electrode Conductor, I know there must be two 10 feet ground rods spaced 6 feet apart but for sake of illustration, let me just use one)

But how about at the back of the GEC toward the main panel (let's say it's located there), what is the voltage gradient? Just estimate (or percentage) and not exact values.

Also it means by putting GEC, the cat has more chance to get shock than not putting any GEC, right?

 

[tersh]

Let me post this last drawing before I got to an island called Batanes later which may not have internet.

First I know that "Current doesn't go to ground. It leaves source and return to source" as Mike put it. The soil is just a conductor. Therefore my GEC and home soil won't feel any current from other poles but the one it is directly connected to, right?

I'd like to clarify the voltage gradient shown in Mike's video and others. Supposed the utility pole is outside the red gate and the centertap is grounded (which really is now), Is this correct?

So the nearer it is to utility ground rod, the bigger is the voltage at the ground?
The nearer to the GEC the less is the voltage? (GEC = Grounding Electrode Conductor, I know there must be two 10 feet ground rods spaced 6 feet apart but for sake of illustration, let me just use one)

But how about at the back of the GEC toward the main panel (let's say it's located there), what is the voltage gradient? Just estimate (or percentage) and not exact values.

Also it means by putting GEC, the cat has more chance to get shock than not putting any GEC, right?

By the way. I need to ask something now about grounded and ungrounded 240v to neutral (no centertap) because only 1/3 of our places in the Philippines uses the centertapped neutral (mostly in capital and those cities with franchise of company Meralco). The rest in the provinces uses 240v to neutral. The province or islanad I'm going later uses such. So may as well hear a tip or two about it.

The above is a service entrance of an American who married a filipina who built a home (above picture) in the rural area in the Philippines (not served by Meralco who used surplus split phase transfomers decades ago in powering up the capital). He wrote a blog about it describing the split phase power in capital and the 240v to neutral in the province.

https://myphilippinelife.com/philippine-electrical-wiring/

Since the lodge I'll stay tonight for one week is powered by 240v to neutral. I need to be familiar with their power system.

Basically. In power lines and home when one of the 240v hot is grounded, what would happen if:

1. There is no GEC in the house? Is GEC more required in utility lines where one hot is grounded versus when centertap is grounded?

2. If the pole ground rod was stolen, and there is another one in pole nearby and it's part of Multi Neutral Network. What is the behavior of partially grounded and partially ungrounded pole? Is there such thing?

3. All my inquiries before are floating secondaries of American split phase power system. Now what is the behavior of floating secondaries of pure 240v to neutral system (where one hot is grounded). Is there a difference in behavior between them as far as ground fault is concerned?

4. My inquiries now is because if the utility company in capital would say they can transfer ground from centertap to one hot leg of our pole in front of the compound (which they may say it's part of their program). Imagine our metal chassis is connected to grounded hot leg, what if someone stole the ground rod, and our pole 240v become floating, then our metal chassis would have 240v potential. Now since it's floating, the effect is just like small isolation transformer? or would there be partially floating scenario where if you touch the metal chassis, then you could still get shock as there is some neutral somewhere it's returning too? What do you think?