Until a protective device like a GFCI or RCD trips your hit with the full available fault current not just some. A GFCI does nothing to limit current until it trips.
GFCI BREAKER ON A DELTA SYSTEM
- Thread starter DJK
- Start date
ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
xFCI breakers are junk that fail while energized, with detrimental reliance on end users to push test buttons monthly.
I would feel better with standards that check Thermal-Magnetic function after push-button resets fail.
RCD has always been available as a separate circuit-breaker function, separate from thermal-magnetic breakers.
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- Location
- Illinois
- Occupation
- retired electrician
So submit a proposal to make a change to UL 489. The system works the same as it does for the NEC as far as making changes.
However there is no practical way to check the operation of the thermal magnetic function of an installed breaker.
ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
It may be easier to collect signatures for a congressional bill, to adopt RCD in place of xFCI, on the national level.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
Could something like this:
Combined with a shunt trip breaker serve the OPs needs?
I'd expect a stand alone ground fault relay to only be considered an acceptable 'GFCI' when combined with an approved disconnection device, and I don't see a list, so I'm leery.
Jonathan
Combined with a shunt trip breaker serve the OPs needs?
I'd expect a stand alone ground fault relay to only be considered an acceptable 'GFCI' when combined with an approved disconnection device, and I don't see a list, so I'm leery.
Jonathan
- Location
- Illinois
- Occupation
- retired electrician
That would be a state's rights issue and unconstitutional.
So you want the code to require us to install two devices in place of one?
ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
Like Roe v. Wade, RCD v. xFCI would protect the right to have an RCD in place of xFCI, and strike down state adoptions of NFPA that prohibit the right to choose.
The choice would depend on availability, since AHJ’s only approve devices listed for the equipment, and OEM’s only make what sells.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Just like users are require to regularly test smoke and carbon dioxide monitors.
How about vehicle warranties that require fluid monitoring?
Thermal-magnetic breakers have almost 100 years of successful installations without the need for 'standard checks". This is similar to the experience with thermostats and boiler/water heater safety valves.
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- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
But, in post 15, you appear to say RCDs prevent shocks.
ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
Vehicle gauges, CO & smoke alarms have flashing idiot lights, readily visible, with audible buzzing, or chirps, not secluded behind silent equipment covers, in locked rooms, or outdoors.
Its unconscionable to expect fuses to fail in the energized state, or detrimentally rely on end users to know the difference between pass or fail while it remains energized.
If subject to federal review, such a standard will likely be struck down.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Fuses??
I thought we were discussing the lack of testing for thermal-magnetic functions of breakers.
ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
End users subject to a reasonable person standard, may regard a fuse box with circuit breakers, or fuses, as one in the same.
“The reasonable person standard is a legal concept used to determine if an individual's actions were negligent by comparing them to what a hypothetical reasonable person would have done in similar circumstances. It serves as a benchmark in negligence cases to assess whether someone acted with ordinary care.”
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
But you as a qualified electrician should not.
ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
Neither should my services, or contracts, fail to offer the required maintenance.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Many of which come from manufacturers that have something to gain by selling product under the name of improved safety whether is fully justifiable or not. Similar to how big pharmacy sort of has big say and leads the way for rules and regulations for medical treatments and procedures. They have deep enough pockets to push their interests into becoming the rules and regulations.
I don't know cost comparison between GFCI/AFCI's and RCD's but that may also be a factor in whether companies like Schneider even have any interest in pursuing any push for RCD's into the North American listing standards and codes or stay with what they have as it likely makes them more $$ in the end.
I've responded to several electrical shock injuries during 45 years of volunteer medical rescue work. I worked that same interval as an electrician. One of the incidents my station's ambulance responded to was an employee at a school cafeteria that had been shocked by contact with a commercial (food) mixer which had been energized by damage to its flexible cord which had severed the Equipment Grounding Conductor (EGC) and faulted one of its 2 energized conductors to the frame. I responded as part of the Engine's crew because calls for pulseless resuscitation always get a manpower unit to help with Cardio Pulmanary Resuscitation while the ambulance crew initiates other care.
Because the City's Lion's club had just given us the first Automated External Defibrillator (AED) to be carried by a basic ambulance in our entire region the victim survived. [When we went to the Lion's club next meeting to announce the results of their donation they clapped, cheered, and cried!]
What's my point? It is axiomatic in emergency medicine that 30 mA through the chest cavity will cause cardiac fibrillation which is inevitably fatal if a defibrillator is not applied within 10 minutes and that for the patient to have a truly positive outcome, meaning a full recovery, it must be applied within 6 minutes of onset and CPR was begun within 3 minutes. So if a Residual Current Detector (RCD) will tolerate 30 mA of current escape from the circuits current carrying conductors and a GFCI will tolerate no more than 5 mA of current escape how can anyone say that RCDs are the better protective device for human safety from electrocution? Please clearly explain what I didn't understand about the postings that said that RCDs are superior to GFCIs. I've never worked on anything that had RCD protection in the US. I saw a couple of them during a project in Argentina but that's as close as I ever got. I'm not claiming that I know but the difference between the 2 sets of numbers offered doesn't seem to support the superiority of RCDs.
I used to do that very thing to one of every 10 circuit breakers we installed in prebuilt communications shelters at Integrated Power Corporation (IPC). We just applied the loads that the manufacturer gave as 2 points on the trip curve, I don't remember which 2 points we used, and timed the opening with a laboratory multimeter with a timing function and memory. What was missing from that testing? Can you explain it so that a factory floor test and installation technician will understand?
Thanks for the feedback I appreciate the discussion, since there is no UL GFCI standard for a 240V delta system, for the OP I was comparing the protection offered by a regular breaker to a Residual Current Device (RCD).
My medical understanding is limited so I do appreciate your feedback, What I have learned is that 30mA for a very limited amount of time is still within the general safe area for the person, this has been studied and determined over multiple years in the US and abroad.
A RCD (in Italy or Germany for example) is required to trip between 20ms and 40ms depending on the location of what we call the main bonding jumper, so for our common 4 wire US system (TN-S) it would be 40 ms. This is a very fast trip time.
My understanding of UL 943 is that they use a formula that states the maximum permitted time to trip in seconds is equal to the quantity (20/fault current in milliamps) raised to the 1.43 power. The application of this formula would permit a 7000 ms (7 second ) trip time for a 5 mA ground fault.
UL (Ground Fault protection of Equipment) GFPE, or Class B GFCI breakers are available but also not for a 240V corner grounded delta. They are rated 30mA but trip slightly above that at around 45mA in around 2000ms.
My understanding of providing ground fault protection from plain old inverse time circuit breakers (regular breaker in your home) is that it typically takes 300% of its rating to trip in 2 seconds.
So in the case of the OP a 40A booster heater breaker it needs 120 Amps to flow for the breaker to trip in 2000ms, and this is of course NEC code compliant (not even on the chart)
Also consider that all devices, especially at 240V and especially heaters have capacitive leakage current and RCDs protect the whole circuit, which "preloads" the RCD with a few mA for each foot of wire or each appliance.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
That 5 or 30 mA is only a direct personnel protection feature when someone comes into contact with something that is energized.
Very few GFCI trip events are situation where the current passed through a victim, and even when that does happen current is not limited only the duration of the current is limited by response time of the device. Usually the device has tripped before anyone has been shocked which is still very successful when it comes to limiting injuries and deaths. I would think 30 mA of protection level instead of 5 would likely still be nearly as successful at tripping before someone is actually part of a current path. I think you would also have less undesired tripping with 30 mA protection which maybe would lessen how many people end up removing, disabling, bypassing GFCI protection in some way yet still leave them with pretty fair protection.
Frank DuVal
Senior Member
- Occupation
- Electrical Contractor, Electrical Engineer
So this section of the NEC does not apply.