I want to install 125Ampere with 100mA tripping current GFCI in subpanel. I'd like to get a list of all nuisance leakage tripping current sources. For example. When some refrigerators defrost, it can trip some GFCI. What is the leakage current in mA of refrigerators defrosting? How about airconditioning? What mA is the tripping current for different capacities or BTUs. And other appliances or pipes leakages, etc. Thanks.
List of all nuasance leakage tripping current sourcces of GFCI
- Thread starter tersh
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- Placerville, CA, USA
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1. If the protective device is not designed for personnel protection with a threshold of approximately 6ma, it is not technically a GFCI under US terminology. It can be called GFP (Ground Fault Protection) or simply a GF detecting device. In the EU it will usually called an RCD (Residual Current Detector). A device in a panel with 100ma sensitivity is not, by definition, a GFCI.
2. You are not likely to find such a list.
The most common and hard to track down cause of current leakage to grounded metal in an appliance is capacitive coupling between wires (as in a motor) or heating elements (as in a defrost heater) and ground. This is not designed in and (obviously) in some cases is not adequately tested for as part of the approval process for a design. Some capacitve coupling is unavoidable, so the goal would have to be to reduce it to a level which will not trip a GF detector.
3. In some cases there is actually inadequate insulation which can produce current leakage and this low insulation resistance to DC can be detected with an ohmmeter or a megger.
4. Air conditioners will not necessarily have a high leakage current and there are no typical values associated with a particular size unit.
Stoves and ovens with a spark igniter or heating appliances with a spark igniter use a high voltage spark from an internal insulated electrode to an internal grounded electrode, with the high voltage being produced by an internal power supply driven from AC. This arc current can in some cases be interpreted as ground fault current in a detector in the supply to the appliance. Again, it is essentially the result of inadequate attention to GF tripping in the design of the unit, but the results in any particular situation can also vary with the way in which the appliance is grounded and the susceptibility of the GF detector to high frequency arc current.
2. You are not likely to find such a list.
The most common and hard to track down cause of current leakage to grounded metal in an appliance is capacitive coupling between wires (as in a motor) or heating elements (as in a defrost heater) and ground. This is not designed in and (obviously) in some cases is not adequately tested for as part of the approval process for a design. Some capacitve coupling is unavoidable, so the goal would have to be to reduce it to a level which will not trip a GF detector.
3. In some cases there is actually inadequate insulation which can produce current leakage and this low insulation resistance to DC can be detected with an ohmmeter or a megger.
4. Air conditioners will not necessarily have a high leakage current and there are no typical values associated with a particular size unit.
Stoves and ovens with a spark igniter or heating appliances with a spark igniter use a high voltage spark from an internal insulated electrode to an internal grounded electrode, with the high voltage being produced by an internal power supply driven from AC. This arc current can in some cases be interpreted as ground fault current in a detector in the supply to the appliance. Again, it is essentially the result of inadequate attention to GF tripping in the design of the unit, but the results in any particular situation can also vary with the way in which the appliance is grounded and the susceptibility of the GF detector to high frequency arc current.
So if the RCD or RCDO (combination residual current and over current (breaker)) will be used. What tripping current will the safest that won't trip spontaneously on any leakage except direct short to metal case in the panel itself. This will be used as backup (or just for sake of discussion)
Adamjamma
Senior Member
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- Jamaica and london
Best bet is talk with a company expert such as Schneider with your actual situation specs.. they will be able to give you better advice than many of us will. In the UK this again would not be allowed in residential RCD places but the 100 setting would be used in commercial places and again as stated above would be for personnel protection more than anything else.. withthe requirement for a tighter RCD in the 30 range to be used in the rest of the installation where required. Newest rules for residential means that you must have 30 RCD in all new residential builds. Including lighting. No more exceptions for second floor and above , or for other old exceptions. All rentals must be upgraded as I understand as well, as they hit their renewal dates for inspections, concerning lighting circuits. Again, this concerns the safety of the consumer if a bulb is broken and needs changed.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
IMHO, if a device that plugs in, such as a refrigerator, trips a GFCI (for personal protection, 6mA), then that device is _broken_ and you are not talking about a nuisance trip.
However for this discussion it seems that we are talking about ground fault detection for purposes of more reliably detecting faults and protecting equipment. For this sort of application I'd suggest that a trip level in the ampere or hundreds of ampere range is more appropriate. For example, when a 480V service requires ground fault protection, the NEC requires a trip level of no more than 1200A. When protecting a feeder, you want proper coordination with downstream protective devices; you don't want the entire building to trip out because the GFP on the main trips before the short circuit trip of a 20A branch circuit.
In the ideal (spend lots of $$ case) each breaker in a system has GFP, and each 'lower level' (smaller, closer to the load) breaker sends a signal to higher level breakers so that only the breaker closest and upstream of the the fault opens. In the real world you often have to coordinate the gfp detection of one breaker with the thermal/magnetic trip characteristics of another breaker.
-Jon
However for this discussion it seems that we are talking about ground fault detection for purposes of more reliably detecting faults and protecting equipment. For this sort of application I'd suggest that a trip level in the ampere or hundreds of ampere range is more appropriate. For example, when a 480V service requires ground fault protection, the NEC requires a trip level of no more than 1200A. When protecting a feeder, you want proper coordination with downstream protective devices; you don't want the entire building to trip out because the GFP on the main trips before the short circuit trip of a 20A branch circuit.
In the ideal (spend lots of $$ case) each breaker in a system has GFP, and each 'lower level' (smaller, closer to the load) breaker sends a signal to higher level breakers so that only the breaker closest and upstream of the the fault opens. In the real world you often have to coordinate the gfp detection of one breaker with the thermal/magnetic trip characteristics of another breaker.
-Jon
hbiss
EC, Westchester, New York NEC: 2014
- Location
- Hawthorne, New York NEC: 2014
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- EC
I really wonder where you get your information from. :happysad: There is no "list". UL specifies the maximum allowable leakage current for any device or piece of equipment and AFAIK it's all the same- well below the 5ma threshold. As was said, if something is tripping a GFCI IT'S DEFECTIVE!
-Hal
JFletcher
Senior Member
- Location
- Williamsburg, VA
The only restriction I am aware of is that some GFCI manufacturers list a maximum wire length downstream from their devices... Usually about 250 ft.
older appliances that have ground-fault leakage are just that older appliances that probably need to be replaced. On a practical note, about the only time I run across tripped GFCI devices from nuisance trips is wet exterior receptacles.
As others have mentioned, a 100 milliamp breaker is not a GFCI. GFPE can be used in certain instances, however I thought the limit on that was 30 milliamps, and you would not be able to combine those ground faults to use a hundred milliamp breaker.
GFPE is not a substitute for GFCI protection.
- Location
- Illinois
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- retired electrician
I believe the limit set by the product standards is 0.5 mA. As you say, if the GFCI is tripping, there is an issue with the equipment.
kwired
Electron manager
- Location
- NE Nebraska
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- EC
Back up of what? This is not going to provide class A GFCI protection.
Yes appliances are supposed to have a maximum leakage level, but they add up and especially when you have not just one branch circuit but an entire panel you are attempting to protect. On top of that you have capacitive leakage within your premises wiring, and the more wiring there is whether on one circuit or multiple circuits the more that capacive leakage may be as seen from the common feeder's perspective.
Tony S
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- Resting under the Major Oak UK
Which regulations/codes are you working to? BS7671 or NEC?
Under BS7671 backup to RCD’s and RCBO’s is sometimes provided by an S type (time delay) front end RCD. I don’t know about the NEC as following a hard drive failure I’ve lost my copies.
Under BS7671 backup to RCD’s and RCBO’s is sometimes provided by an S type (time delay) front end RCD. I don’t know about the NEC as following a hard drive failure I’ve lost my copies.
Although I have residence in New York. I also have family home in the Philippines. Most homes there lack any grounding and even the utility poles have very poor wiring. And contractors don't follow codes because they just pay city hall $20 and enough to escape. And we don't use GFCIs too. Hence for my parents old house where grounding is not present, it would be impossible to replace all feeders with grounding wire. I plan to use 125A RCBO (Residual Current Circuit Breaker with Overcurrent) with 100mA tripping current. Our original main breaker is 125A. What tripping current would be ok to be used in main panel that would only trip if any hot shorts to ground? I don't mind if the entire house has power failure. It's better to be safe than getting shock from hot touching any enclosure.
You may tell me to just put grounding. But for now it's not possible because the house is part of a compound and all neighbors won't allow replacing feeders under the driveway. So instead of convincing me to convince my neighbors or sue them. Just share what tripping current must be used that won't trip from all combined leakage currents in appliciances and capacitive coupling for typical 2 storey house with 125A main breaker? Just estimate. Thanks.
Tony S
Senior Member
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- Resting under the Major Oak UK
Adamjamma
Senior Member
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- Jamaica and london
Tony S, you dont have a copy of Bermuda, Jamaica or Trinidad in your toolbox over there as well, do you???
Thanks
Thanks
hbiss
EC, Westchester, New York NEC: 2014
- Location
- Hawthorne, New York NEC: 2014
- Occupation
- EC
Didn't we already discuss this? If nothing is grounded including the service then how is that going to work?? Besides, 100ma will kill them.
-Hal
Adamjamma
Senior Member
- Location
- Jamaica and london
so all you can do is treat everything like you are dealing with an old two wire outlet then, and put a gfci as the first outlet on each circuit, then? Kinda like we have to use an RCD at 30ma here in London on any T T homes... where the ground is iffy or not low enough?
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
The term 'ungrounded' is used in two ways.
One, IMHO the proper usage, is where the transformer secondary is floating, with no intentional bonding between the circuit and earth or bonded conductors.
The second usage describes circuits run without a separate 'EGC'. The system is almost certainly grounded (the neutral circuit conductor is bonded to ground) but there isn't a separate bonding conductor used for things such as equipment chassis connection.
I misunderstood the reason for the original question. I had ass-u-med using some sort of ground fault detection on a feeder to provide an additional level of protection over the standard method of using overcurrent to detect faults. Residual current detection will respond much more rapidly and at a lower fault current to most (but not all) faults.
However it seems that the real desire is to provide personal protection. In this case you really want class A gfci protection, and you probably _don't_ want to do this at the level of a 125A feeder. All devices have some leakage current, and there is expected capacitive coupling between wires...and all of this expected leakage will add up to nuisance tripping. In a small house wired without electronic dimmers and with circuits that don't have EGCs, the leakage might be low enough to get away with a single class A GFCI, but I would not bet on it.
In which case what you really want to do is get separate GFCI breakers for each circuit, or use GFCI receptacles.
-Jon
One, IMHO the proper usage, is where the transformer secondary is floating, with no intentional bonding between the circuit and earth or bonded conductors.
The second usage describes circuits run without a separate 'EGC'. The system is almost certainly grounded (the neutral circuit conductor is bonded to ground) but there isn't a separate bonding conductor used for things such as equipment chassis connection.
I misunderstood the reason for the original question. I had ass-u-med using some sort of ground fault detection on a feeder to provide an additional level of protection over the standard method of using overcurrent to detect faults. Residual current detection will respond much more rapidly and at a lower fault current to most (but not all) faults.
However it seems that the real desire is to provide personal protection. In this case you really want class A gfci protection, and you probably _don't_ want to do this at the level of a 125A feeder. All devices have some leakage current, and there is expected capacitive coupling between wires...and all of this expected leakage will add up to nuisance tripping. In a small house wired without electronic dimmers and with circuits that don't have EGCs, the leakage might be low enough to get away with a single class A GFCI, but I would not bet on it.
In which case what you really want to do is get separate GFCI breakers for each circuit, or use GFCI receptacles.
-Jon
hbiss
EC, Westchester, New York NEC: 2014
- Location
- Hawthorne, New York NEC: 2014
- Occupation
- EC
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
We will need tersh to explain what the situation is. I read ' Hence for my parents old house where grounding is not present, it would be impossible to replace all feeders with grounding wire. ' as meaning that they had eg. 2 conductor romex run to the various receptacles but that the supply transformer neutral was probably (if not reliably) bonded to ground, but am not sure.
-Jon
-Jon
Here is the actual situation All of the 16 breakers in the main panel will be 5mA GFCI (two already put and the others to be installed soon by qualified electrician). This will protect each circuit and each appliance in the house. But what will protect the main panel enclosure itself? So the purpose of the main breaker RCBO is to protect the main panel enclosure only. However, the RCBO won't be put in the same main panel but another one before the main panel. This is the picture of the main panel.
The following is second disconnect or main breaker connected before the main panel above. It is here where I will replace it with a rail DIN type RCBO.
And there is a third main breaker outside the residence:
The main breaker outside the residence is rated 150A,
the 2nd disconnect is rated 150A
the main panel breaker (with 16 pcs of 5mA GFCI) is rated 125A.
The transformer secondary is floating 240v and I just can't connect a ground wire because it would mean jack hammering all the driveway concrete and neighbors won't allow.
I will only replace the 2nd disconnect breaker with 125A breaker with 100mA residual tripping current. This is just to protect the main panel metal enclosure itself if any hot shorts to the enclosure (remember this.. it's not to protect other appliance downstream which will be protected by 16 pcs of 5mA GFCI). Since the main panel metal enclosure is connected to concrete, the 100mA can trip if there is a short. But I just don't want the 100mA to trip spontaneously from nuisance leakage current. What tripping current must I use to be safe it won't trip? Don't worry about each appliances because they would be protected by 16 pcs of 5mA GFCI. Thanks.
The following is second disconnect or main breaker connected before the main panel above. It is here where I will replace it with a rail DIN type RCBO.
And there is a third main breaker outside the residence:
The main breaker outside the residence is rated 150A,
the 2nd disconnect is rated 150A
the main panel breaker (with 16 pcs of 5mA GFCI) is rated 125A.
The transformer secondary is floating 240v and I just can't connect a ground wire because it would mean jack hammering all the driveway concrete and neighbors won't allow.
I will only replace the 2nd disconnect breaker with 125A breaker with 100mA residual tripping current. This is just to protect the main panel metal enclosure itself if any hot shorts to the enclosure (remember this.. it's not to protect other appliance downstream which will be protected by 16 pcs of 5mA GFCI). Since the main panel metal enclosure is connected to concrete, the 100mA can trip if there is a short. But I just don't want the 100mA to trip spontaneously from nuisance leakage current. What tripping current must I use to be safe it won't trip? Don't worry about each appliances because they would be protected by 16 pcs of 5mA GFCI. Thanks.
Tony S
Senior Member
- Location
- Resting under the Major Oak UK
Do you have a copy of the Philippines code to hand? No, neither do I, other than the link I posted.
The two breakers in the OP’s third photograph look like VO-ELCB’s, they’ve not been installed in the UK since the late 60’s early 70’s although they keep cropping up now and again.
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