Circuit Breaker teardown and defective Siemens latching mechanism

[romex jockey]

it measured about 0.0835 or 0.083 when pressed with pressure. You measured the original GE bus bar stub to be 0.094. Is the difference significant? If the GE spring clips were flat, and applying basic trigo, would the contact only be at the edge with mostly gap in the middle?

I would imagine the tolerance dependent on this propritory 'spring clip bump' capabilities?

<snip>

From the measurements and previous handling of the Siemens. I think the Siemens bus bar stub is thicker than the GE bus bar stub 0.094 thickness. I guess the Siemens PL center stub measures about 0.100 or more? How much can this really affect the contact areas if north American panels and breakers were mixed?

Siemens seems to have every bit of info, save for this specification>
This is zoom out of it:

https://w3.usa.siemens.com/powerdis...alog/Documents/2017/SF-17-Sect-01-ALL-web.pdf

I have none in stock (we use GE) , so i'll have to find one in the field for you tersh

~RJ~

 

[tersh]

I see a sliver of the screw shell. What if I touched it while unscrewing the bulb?

Yesterday when buying the caliper, I took this picture of the ceiling bulb outlet at the one stop depot. You can see the screw shell is way inside the plastic receptacle. The reason 100% of electricians changed it without turning off the breaker is because it's unlikely they would suddenly touch the shell inside the casing knowing it's live.

Anyway. I'd like to know something. This is unrelated to the above. Is there any situation in the US where the dweller acquire 120 volts via GEC alone and not via the neutral? I mean if you connect one of the phase to the soil, you would get 120 volts. Supposed 10 feet electrodes rod were inserted into the soil. Won't this produce stable 120 volts even just 100mA to power the 120v circuitry of the say 6 pcs of Siemens GFCI breakers?

In the residential house. The contractor has to demolish the concrete in the parking to replace 30 meters of old 2 wire feeder with new 3 wire with ground wire and replace all the 6 townhouse service entrance panels and wiring and the 5 neighbors definitely won't allow that so there is no way to add third ground wire to connect to the Poco hanging neutral/ground wire at the service entrance. Even just replacing a single breaker at service entrance needs full electrical plan and permit from city hall. This government policy is to ensure no one would just change the service entrance components without full scrutiny from the city hall and electrical division.

 

[kwired]

Every panel manufacturer uses a different shape of bus bar, requiring different shaping on the breaker's spring clip. They are different because of patents. Each manufacturer has patented their shape, because they think it outperforms their competitor's shape (and avoids violating their competitor's patents). Eventually patents expire, such as Square D's QO (queue oh) patent expired, permitting Murray/Siemens to manufacture its QD (queue dee) breakers for QO panels. Still, Siemens is unable to make breakers that fit both Murray and QO panels, because they are still different. They are locked into the old designs because new breakers need to fit old and new panels alike.

So when you use an alien breaker, the clips and nubs don't mate as intended by the two manufacturers, and this is not an accident, it's by design. They are not trying to keep you from using alien breakers, they are (were) trying to keep from being sued for patent infringement. Anyway, you end up with the clips only mating at 2-4 points instead of flat surface contact, and point contact like that is only good for a couple of amps before it starts melting, opening, arcing and burning. "

​

​

Using Square D's QO series in the comparison - QO bus to breaker connection design is so much different than GE, Siemens and others like them that there is no way they even come close to being able to interchange. Yes the "plug on" part of the design is similar, but the QO bus is like 1/4 or 5/16 inch wide vs only around 1/8 inch wide for GE, Siemens, and others of similar design. You can plug a GE breaker into a Siemens panel and it will fit there and make reasonable contact. A QO breaker is different enough it won't work at all in the GE or Siemens panel and vice versa. Cutler Hammer CH series and Square D's QO series are the only two out there that are similar in their bus connection design, but other mounting features of the breaker still make them not fit into each other's panels very well at all.

 

[mbrooke]

Yesterday when buying the caliper, I took this picture of the ceiling bulb outlet at the one stop depot. You can see the screw shell is way inside the plastic receptacle. The reason 100% of electricians changed it without turning off the breaker is because it's unlikely they would suddenly touch the shell inside the casing knowing it's live.

So as soon as the bulb is inserted and touches the metal inside, the screw shell on the bulb can not be touched?

Anyway. I'd like to know something. This is unrelated to the above. Is there any situation in the US where the dweller acquire 120 volts via GEC alone and not via the neutral? I mean if you connect one of the phase to the soil, you would get 120 volts. Supposed 10 feet electrodes rod were inserted into the soil. Won't this produce stable 120 volts even just 100mA to power the 120v circuitry of the say 6 pcs of Siemens GFCI breakers?

In the US TT earthing is not allowed, and you can not use a GEC as a neutral.

In the residential house. The contractor has to demolish the concrete in the parking to replace 30 meters of old 2 wire feeder with new 3 wire with ground wire and replace all the 6 townhouse service entrance panels and wiring and the 5 neighbors definitely won't allow that so there is no way to add third ground wire to connect to the Poco hanging neutral/ground wire at the service entrance. Even just replacing a single breaker at service entrance needs full electrical plan and permit from city hall. This government policy is to ensure no one would just change the service entrance components without full scrutiny from the city hall and electrical division.

Worse come to worse, drive those ground rods anywhere around the building and run the GEC all the way back to the mains.

 

[tersh]

So as soon as the bulb is inserted and touches the metal inside, the screw shell on the bulb can not be touched?

Yes. Why. In the US, your screw shell was exposed without any plastic or porcelain enclosure?

In the US TT earthing is not allowed, and you can not use a GEC as a neutral.








Worse come to worse, drive those ground rods anywhere around the building and run the GEC all the way back to the mains.

You mean the GEC would be bonded to the main panel neutral bar instead of ground bar. And ground and neutral bonded at main panel just like the US?

In the US. GEC is connected to the Ground. Neutral is connected to the PoCo Neutral, and they are bonded once in the main panel. Hence Neutral is in ground potential, but current can still pass through neutral even when it's in ground potential. So your GEC is important so that there is zero potential between the appliance enclosure and the soil.

In the hypothetical case the GEC would be tapped to Neutral (instead of Ground) in main panel to power the 120v circuits of the 6 Siemens GFCI. There is no more separate ground to be connected to the GEC. But then in the US the neutral and ground is bonded at main panel. So it's like the GEC is connected to neutral too. However since your neutral is connected to PoCo centertapped neutral directly. Then your neutral has low impedance path to transformer. Without this low impedance tap. Then it's like you have the neutral bonded to ground at main panel and it's only connected to the GEC.

But isn't this dangerous when the main panel enclosure is connected to ground which is bonded to neutral. And if neutral was used to power the 6 Siemens GFCI and it's also connected to enclosure. What would happen if you touch the enclosure? Would you get a shock or since it's connected to GEC. It's at ground potential?

I won't do it. Just asking to review what I learnt in the latter part of last year when I was learning the above

Thanks.

 

[mbrooke]

Yes. Why. In the US, your screw shell was exposed without any plastic or porcelain enclosure?

When screwing in the bulb, yes, its possible to touch the screw shell on the bulb while it electrically contacts the socket threads.

You mean the GEC would be bonded to the main panel neutral bar instead of ground bar. And ground and neutral bonded at main panel just like the US?

GEC goes to the main disconnect or panel. From the main disconnect/panel ground and neutral become separate.

In the US. GEC is connected to the Ground. Neutral is connected to the PoCo Neutral, and they are bonded once in the main panel. Hence Neutral is in ground potential, but current can still pass through neutral even when it's in ground potential. So your GEC is important so that there is zero potential between the appliance enclosure and the soil.

As soon as the neutral has load on it, it is no loner at remote earth potential. Same for a fault.

In the hypothetical case the GEC would be tapped to Neutral (instead of Ground) in main panel to power the 120v circuits of the 6 Siemens GFCI. There is no more separate ground to be connected to the GEC. But then in the US the neutral and ground is bonded at main panel. So it's like the GEC is connected to neutral too. However since your neutral is connected to PoCo centertapped neutral directly. Then your neutral has low impedance path to transformer. Without this low impedance tap. Then it's like you have the neutral bonded to ground at main panel and it's only connected to the GEC.

But isn't this dangerous when the main panel enclosure is connected to ground which is bonded to neutral. And if neutral was used to power the 6 Siemens GFCI and it's also connected to enclosure. What would happen if you touch the enclosure? Would you get a shock or since it's connected to GEC. It's at ground potential?

I won't do it. Just asking to review what I learnt in the latter part of last year when I was learning the above

Thanks.

Depends on the soil resistance and how much power the GFCI breakers use. The higher the rod resistance or the more power the GFCI breakers use, the higher the voltage will be to remote earth.

 

[tersh]

When screwing in the bulb, yes, its possible to touch the screw shell on the bulb while it electrically contacts the socket threads.





GEC goes to the main disconnect or panel. From the main disconnect/panel ground and neutral become separate.















As soon as the neutral has load on it, it is no loner at remote earth potential. Same for a fault.

But I read somewhere last year that even if neutral has load on it. It is at zero potential *with respect* to earth potential. But none zero potential with respect to the load and transformer. I'll find the diagram and show you.


There is also the concept of Open Neutral that I'm trying to relate to the concept of Open GEC path. In Open Neutral. If it became open, the enclosure would be electrified because they would form return path. So without a true Neutral. Then a GEC connected to the neutral would become an open neutral hazard? Wait let me review Mike Holt treatise on hazard of open neutral and apply it to the scenario where there is no neutral and only GEC used to power 120v circuits. There is a connection in the hazards if in essence it's simply a case of Open Neutral Hazard. But then if you won't ground any enclosure, then no hazard isn't it because no return path.

Depends on the soil resistance and how much power the GFCI breakers use. The higher the rod resistance or the more power the GFCI breakers use, the higher the voltage will be to remote earth.

 

[mbrooke]

But I read somewhere last year that even if neutral has load on it. It is at zero potential *with respect* to earth potential. But none zero potential with respect to the load and transformer. I'll find the diagram and show you.

If you are assuming the head of the ground rod is the earth. Other then that, there will be voltage from voltage drop across the neutral.

There is also the concept of Open Neutral that I'm trying to relate to the concept of Open GEC path. In Open Neutral. If it became open, the enclosure would be electrified because they would form return path. So without a true Neutral. Then a GEC connected to the neutral would become an open neutral hazard? Wait let me review Mike Holt treatise on hazard of open neutral and apply it to the scenario where there is no neutral and only GEC used to power 120v circuits. There is a connection in the hazards if in essence it's simply a case of Open Neutral Hazard. But then if you won't ground any enclosure, then no hazard isn't it because no return path.

Look at it like this: an open neutral is simply a higher Z then an intact neutral. Meaning a closed neutral might be 0.02 ohms, an open neutral as infinite or in the case of a poor splice 2000 ohms. The higher the neutral Z, the more voltage drop there is across said neutral.

 

[tersh]

If you are assuming the head of the ground rod is the earth. Other then that, there will be voltage from voltage drop across the neutral.




Look at it like this: an open neutral is simply a higher Z then an intact neutral. Meaning a closed neutral might be 0.02 ohms, an open neutral as infinite or in the case of a poor splice 2000 ohms. The higher the neutral Z, the more voltage drop there is across said neutral.

If there is more voltage drop across said neutral. Why would this make the appliance enclosure become energized as it takes the return path to source instead of the neutral? The way I imagined hazard of open neutral before was the current are like cars. When the bridge (neutral) is cut off. They would take different alternative roads (in the case of current, the chassis/enclosure path to soil and back to source). If you will think it in terms of voltage drop. Why would bigger voltage drop across neutral translate to the current taking alternative path?

 

[mbrooke]

If there is more voltage drop across said neutral. Why would this make the appliance enclosure become energized as it takes the return path to source instead of the neutral? The way I imagined hazard of open neutral before was the current are like cars. When the bridge (neutral) is cut off. They would take different alternative roads (in the case of current, the chassis/enclosure path to soil and back to source). If you will think it in terms of voltage drop. Why would bigger voltage drop across neutral translate to the current taking alternative path?

Return path has Z, when its the earth, often 25 ohms.

If you have a 25 ohm load, a 25ohm ground rod acting as a return to an open service neutral, the grounding system will be at 60 volts to remote earth. A higher Z load will cause less voltage, and higher Z rod more voltage.

 

[tersh]

Return path has Z, when its the earth, often 25 ohms.

If you have a 25 ohm load, a 25ohm ground rod acting as a return to an open service neutral, the grounding system will be at 60 volts to remote earth. A higher Z load will cause less voltage, and higher Z rod more voltage.

Ok. Got it. The danger of open neutral service is electrified enclosure and voltage divider to the loads producing overvoltage and undervoltage in some. So if you eliminate connecting the GEC to the any enclosure or chassis (including the panel chassis) and not having other loads to it. Then no hazard of open neutral.

But I want to know something. Google first page about TT system is :"The TT system: Technique for the protection of persons: the exposed conductive parts are earthed and residual current devices (RCDs) are used."

What countries or places where the soil were purposedly made as return current? How stable is it? If you live in our place and want the 120v in soil to power the 120v circuits in the GFCI by bonding the neutral of it only to the GEC and nothing else (except the normal phase connections). How stable do you think the connections would be? Would it give 24/7 uninterruptable 120v current even in the worse of drough when many trace of water in the soil evaporated? What current is the minimum from this scenario in US soil ever recorded? What part of US is like sahara desert? ​

 

[kwired]

Originally Posted by tersh
Yes. Why. In the US, your screw shell was exposed without any plastic or porcelain enclosure?





Whether it is exposed in any way or not, we attach grounded conductor (when used) to the shell partly because that is the easier component to come in contact with when there is no lamp in the socket.

 

[mbrooke]

Ok. Got it. The danger of open neutral service is electrified enclosure and voltage divider to the loads producing overvoltage and undervoltage in some. So if you eliminate connecting the GEC to the any enclosure or chassis (including the panel chassis) and not having other loads to it. Then no hazard of open neutral.

Correct.

But I want to know something. Google first page about TT system is :"The TT system: Technique for the protection of persons: the exposed conductive parts are earthed and residual current devices (RCDs) are used."

What countries or places where the soil were purposedly made as return current?​

France is one country which comes to mind.

How stable is it?

Very stable when you have soil that isn't rocks, typically moist to some degree, and have a rod(s) driven deep enough.

If you live in our place and want the 120v in soil to power the 120v circuits in the GFCI by bonding the neutral of it only to the GEC and nothing else (except the normal phase connections). How stable do you think the connections would be? Would it give 24/7 uninterruptable 120v current even in the worse of drough when many trace of water in the soil evaporated? What current is the minimum from this scenario in US soil ever recorded? What part of US is like sahara desert?

​

In TT you do not use the earth as a return. In theory constantly passing current into the earth would dry out the soil around the ground rod as its not a ultra low Z.

 

[tersh]

Correct.



France is one country which comes to mind.




Very stable when you have soil that isn't rocks, typically moist to some degree, and have a rod(s) driven deep enough.




In TT you do not use the earth as a return. In theory constantly passing current into the earth would dry out the soil around the ground rod as its not a ultra low Z.

I'd like to share with you the ineptness of our electrical contractors and electrician even in office/commercial building electrical installation. Look at the panel in the office building (with third wire only bonded to the panel):

top shot

mid-bottom shot:

It's bolt-on panels which we use in office or commercial building to address vibrations from the street. What applications in the US do you use bolt-on breakers?

Did you see the ground bar? It's not bonded to the casing (there is a plastic holding it). Since all the outlets in office/commercial buildings in the country are still 2-wire just like residential (except the aircon wiring which has 3rd ground wire but the installer never bond it to the aircon external condenser chassis). Then the purpose of the third ground wire in office/commercial buildings is just for display (to show to inspectors). And even the inspector ignored the ground bar plastic part.


In the future I need to have the electrician get the ground bar replaced or at least bond it to the panel (to protect the panel against ground fault), any idea how to bond it to panel?

But right now we can't do that because we can't open the service entrance panel even to turn a breaker off because of arc flash hazard.

I'm looking for US made PPE to protect against

1.2 cal/cm2 to 4.8 cal/cm2 incident energy. Know any idea of full arm gloves and face shield that can do that? What do you use in the US for Arc Flash Category 1 PPE?​

 

[mbrooke]

I'd like to share with you the ineptness of our electrical contractors and electrician even in office/commercial building electrical installation. Look at the panel in the office building (with third wire only bonded to the panel):

top shot

mid-bottom shot:

I see a red wire coming out of the large conduit with the Green and White wires? Or does that red go else where? There is no established EGC color? I see black, blue and Red as an EGC.

It's bolt-on panels which we use in office or commercial building to address vibrations from the street. What applications in the US do you use bolt-on breakers?

Same here- commercial is typically bolt on. From my understanding its not about vibration but the heavier loads and busbar burnouts.

Did you see the ground bar? It's not bonded to the casing (there is a plastic holding it). Since all the outlets in office/commercial buildings in the country are still 2-wire just like residential (except the aircon wiring which has 3rd ground wire but the installer never bond it to the aircon external condenser chassis). Then the purpose of the third ground wire in office/commercial buildings is just for display (to show to inspectors). And even the inspector ignored the ground bar plastic part.

I see that- ground bar needs to be bonded to the panel. No 3 wire outlets in the building?

In the future I need to have the electrician get the ground bar replaced or at least bond it to the panel (to protect the panel against ground fault), any idea how to bond it to panel?

Any place to drill a hole for a thread and bolt? Make sure you use something like a #8.

But right now we can't do that because we can't open the service entrance panel even to turn a breaker off because of arc flash hazard.

I'm looking for US made PPE to protect against

1.2 cal/cm2 to 4.8 cal/cm2 incident energy. Know any idea of full arm gloves and face shield that can do that? What do you use in the US for Arc Flash Category 1 PPE?​

I'll leave that for the experts in arc flash. To be honest I've worked many panels live, despite technically being dangerous.

 

[tersh]

I see a red wire coming out of the large conduit with the Green and White wires? Or does that red go else where? There is no established EGC color? I see black, blue and Red as an EGC.

They didn't use color codes, just using whatever wires they have on stock. The red is the ground wire for the green and white main wires.

Same here- commercial is typically bolt on. From my understanding its not about vibration but the heavier loads and busbar burnouts.



I see that- ground bar needs to be bonded to the panel. No 3 wire outlets in the building?

None. You can't see normal 3 wire outlets anywhere in the country. Only aircon condensers have 3 wire (the conduit is put externally above the ceiling.. actually I told them to add third wire for the aircon because normally they won't). But one of my problems now is all the external aircon condensers don't have the chassis connected to the ground wire provided (because I wasn't there during aircon installation to tell them to ground it).

Any place to drill a hole for a thread and bolt? Make sure you use something like a #8.

A separate thread and bolt and use a wire to connect it to existing ground bar with plastic?

I'll leave that for the experts in arc flash. To be honest I've worked many panels live, despite technically being dangerous.

Not just 120/240v? You are not afraid of arc flash for 480v commercial ac supply?

 

[mbrooke]

They didn't use color codes, just using whatever wires they have on stock. The red is the ground wire for the green and white main wires.

Got it.

None. You can't see normal 3 wire outlets anywhere in the country. Only aircon condensers have 3 wire (the conduit is put externally above the ceiling.. actually I told them to add third wire for the aircon because normally they won't). But one of my problems now is all the external aircon condensers don't have the chassis connected to the ground wire provided (because I wasn't there during aircon installation to tell them to ground it).

Ok. Can this be fixed?

A separate thread and bolt and use a wire to connect it to existing ground bar with plastic?

Or do this- I see bolts holding the busbar pan to the enclosure. Take a #8, land it on the ground bar and take the other landing it underneath on of the bolts.

Not just 120/240v? You are not afraid of arc flash for 480v commercial ac supply?

I am afraid. But working live was more convenient- especially during the day when it inconvenienced people.


But I'll just say this. The arc flash on some large 480 volt services is so severe its called an arc blast. One where not even a bear suite will protect you. In fact they say that a bear suite is an open casket funeral while no bear suite is a closed casket. the amount of energy is beyond words.

 

[mbrooke]

BTW, what is feeding the panel you pictured? I just want to see the system as a whole.

 

[tersh]

BTW, what is feeding the panel you pictured? I just want to see the system as a whole.

What's feeding it is a breaker (right most) in the same main service panel where the arc flashed 3 phase breaker occurred (at the left side not shown). The reason the ground wire turned from black color to red is because halfway he spliced it. Now I'm afraid to let electrician even turn off any breaker without wearing any PPE:

This is especially after an expert wrote me in the arc flash forum: "What you describe is what Alicia Stoll's experiment was testing for and is known as the Stoll curve. It is equal to 1.2 cal/cm2 at 1 second and extends out to about 2.0 cal/cm2 at 2 seconds. This is the onset of a second degree burn. However your question is also talking about the onset of a second degree burn to a hand. IEEE 1584 uses the onset of a second degree burn to the face/chest area so the arc flash boundary would be defined at 18" away. In open air the incident energy quadruples if you half the distance. So 1.2 cal/cm2 at the face/chest would be 4.8 halfway down the arms. Let's just say that other than avoiding burns in the first place, we are never going to protect the hands."

What if I let the electrician wrap 2 shirts around his arms just to turn off one breaker in case the room or subpanel to it needs servicing. This would protect his arms in the event of spontaneous arc flash from the dusts (some may be conductive). Isn't it?

But there are thousands of service panels that don't encounter arc flashes. But in my case, the contractor omit to install the main breaker upstream of it and the 3 phase open delta just serve my office building and another besides it so the incident energy at the panel would be greater than any other place. ​

 

[mbrooke]

Ok, as I promised, some good electrical installs as examples and to go by.


Here is a panel full of 208 volt circuits- the main wires have not been pulled yet:

Residential: