Who invented GFCI protection?

[mbrooke]

I routinely hear Charles Dalziel taking credit for his patent in 1961, but I keep bumping into reports saying GFCIs existed decades earlier.


For example, page 6:

https://eduscol.education.fr/sti/si...es/ressources/techniques/3336/3336-ect173.pdf

 

[synchro]

Here's another reference to early residual current breakers if you haven't already seen it (see 4th page):

https://www.google.com/url?sa=t&sou...IBRAB&usg=AOvVaw0G49EOQ-zygUjqnxkoyeb9#page=4

 

[mbrooke]

Yup- 1940s is what I keep bumping into and with the intent to stop electric shock/electrocution in the 50s.

 

[Ravenvalor]

I was told that they were originally intended to protect patients in hospitals from being electrocuted by all of the wires attached to them during surgery and other procedures.

 

[mbrooke]

Never heard that one before.

 

[kwired]

Weren't they first introduced into NEC sometime in mid 1960's for swimming pool applications and then for bathroom receptacles, though the bathroom receptacles might have been late 60's or even early 70's?

 

[mbrooke]

Swimming pools then outdoor receptacles in the early 70s. Then bathrooms in the mid 70s. I remember homes from the 70s-80s being wired with a GFCI breaker that hit the exterior, garage and bath outlets.

 

[retirede]

Swimming pools then outdoor receptacles in the early 70s. Then bathrooms in the mid 70s. I remember homes from the 70s-80s being wired with a GFCI breaker that hit the exterior, garage and bath outlets.

My house was built in ‘97. Outdoor receptacle outlets are fed from the load side of bathroom GFCI receptacles.

I think that was common and compliant at the time.

 

[Jraef]

You are conflating GFCI with an RCD, they are not the same. GFCI is a very specific term for a PERSONNEL protective device that trips at 5mA, +-1mA. Charles Dalziel (a UC Berkeley professor) was investigating the effects of electric shock on humans and determined the amount of current flow at 60Hz that would produce a “lock” grasp response, which is what was leading to many electrocutions. He determined that in a normal human, each 1mA of current causes us to exert 10lbs of force. So the 5mA threshold had to do with how much counter force you could muster to overcome that caused by the shock in order to get you off of the connection. Contrary to popular belief it has nothing to do with how much current will stop your heart, it’s all about being able to let go of something shocking you.

RCDs existed prior to that, but typically had a 30mA threshold, as they still do elsewhere in the world. Dalziel’s contribution was a circuit that reliably worked at 5mA and has become our standard. Outside of North America that is not the case and people use 30nA RCDs, as they were prior to Dalziel.

So did Charles Dalziel invent the GFCI? Yes. Did he invent the RCD ground fault detection system? No, it already existed. I don’t know who invented that but I suspect someone in Europe.

 

[norcal]

You are conflating GFCI with an RCD, they are not the same. GFCI is a very specific term for a PERSONNEL protective device that trips at 5mA, +-1mA. Charles Dalziel (a UC Berkeley professor) was investigating the effects of electric shock on humans and determined the amount of current flow at 60Hz that would produce a “lock” grasp response, which is what was leading to many electrocutions. He determined that in a normal human, each 1mA of current causes us to exert 10lbs of force. So the 5mA threshold had to do with how much counter force you could muster to overcome that caused by the shock in order to get you off of the connection. Contrary to popular belief it has nothing to do with how much current will stop your heart, it’s all about being able to let go of something shocking you.

RCDs existed prior to that, but typically had a 30mA threshold, as they still do elsewhere in the world. Dalziel’s contribution was a circuit that reliably worked at 5mA and has become our standard. Outside of North America that is not the case and people use 30nA RCDs, as they were prior to Dalziel.

So did Charles Dalziel invent the GFCI? Yes. Did he invent the RCD ground fault detection system? No, it already existed. I don’t know who invented that but I suspect someone in Europe.

I have heard that RCD's originated in the mines in South Africa, but have no proof of that.

 

[mbrooke]

My house was built in ‘97. Outdoor receptacle outlets are fed from the load side of bathroom GFCI receptacles.

I think that was common and compliant at the time.

Common and complaint- liked the approach.

 

[mbrooke]

You are conflating GFCI with an RCD, they are not the same. GFCI is a very specific term for a PERSONNEL protective device that trips at 5mA, +-1mA. Charles Dalziel (a UC Berkeley professor) was investigating the effects of electric shock on humans and determined the amount of current flow at 60Hz that would produce a “lock” grasp response, which is what was leading to many electrocutions. He determined that in a normal human, each 1mA of current causes us to exert 10lbs of force. So the 5mA threshold had to do with how much counter force you could muster to overcome that caused by the shock in order to get you off of the connection. Contrary to popular belief it has nothing to do with how much current will stop your heart, it’s all about being able to let go of something shocking you.

I disagree- on the broader scale they are one in the same. 30ma is indeed personal protection. There is no difference between 5ma and 30ma pickups, what matters is the time in which the GFCI/RCD trips.

RCDs existed prior to that, but typically had a 30mA threshold, as they still do elsewhere in the world. Dalziel’s contribution was a circuit that reliably worked at 5mA and has become our standard. Outside of North America that is not the case and people use 30nA RCDs, as they were prior to Dalziel.

So did Charles Dalziel invent the GFCI? Yes. Did he invent the RCD ground fault detection system? No, it already existed. I don’t know who invented that but I suspect someone in Europe.

Dalziel's circuit has astronomical failure rates in comparison. Though to be fair 5ma (which is actually a slow starting point becoming faster beyond) is a much more complex pickup to achieve than 30ma. I'd go on a limb and call 5ma a "litigation resistant" threshold.

 

[goldstar]

See if this helps :
http://www.pceca.net/images/stories/nec_gfci_requirements.pdf

 

[kwired]

My house was built in ‘97. Outdoor receptacle outlets are fed from the load side of bathroom GFCI receptacles.

I think that was common and compliant at the time.

I hardly ever encountered that on custom homes, aren't really any tract homes in the area here though I could imagine it would have been common on those. I found it a lot on manufactured homes built in the 80-90's though.

Sometimes even figured out the ground fault was at or plugged into a heat tape receptacle located under the home, but messes with you when troubleshooting until you have seen it a time or two that that bath GFCI might be supplying anything that would have been required to be GFCI protected when it was new. Now if they complain about that GFCI tripping I know several places to investigate before getting really serious about tracing things out.

 

[growler]

My house was built in ‘97. Outdoor receptacle outlets are fed from the load side of bathroom GFCI receptacles.

I think that was common and compliant at the time.

1996 NEC. 210-52 Dwelling Unit Receptacle Outlets (d) Bathrooms. In dwelling units, at least one wall receptacle outlet shall be installed in bathrooms adjacent to each basin location. Bathroom receptacle outlets shall be supplied by st least one 20-ampere branch circuit. Such circuits shall have no other outlets.

The fact that your house was built in 1997 doesn't mean they had adopted the latest code cycle. For areas that had adopted the 1996 NEC this would have been a code violation.

I wish I had some older code books to see when the change occurred. Maybe someone with a collection of older code books will look it up.

 

[Tony S]

I’ve worked on E/F switchgear from the 1920’s

Look for a book “Arcs, Sparks and Engineers” a history of A Reyrolle & Co.

 

[kwired]

1996 NEC. 210-52 Dwelling Unit Receptacle Outlets (d) Bathrooms. In dwelling units, at least one wall receptacle outlet shall be installed in bathrooms adjacent to each basin location. Bathroom receptacle outlets shall be supplied by st least one 20-ampere branch circuit. Such circuits shall have no other outlets.

The fact that your house was built in 1997 doesn't mean they had adopted the latest code cycle. For areas that had adopted the 1996 NEC this would have been a code violation.

I wish I had some older code books to see when the change occurred. Maybe someone with a collection of older code books will look it up.

What change are you looking for other than the one you mentioned occurred in 1996?

Before that change I usually put bath receptacle on an adjacent bedroom circuit. (we usually ran 20 amp circuits to all receptacles and 15 amp circuits to lighting outlets only, and I still do that most the time). Since then 20 usually 20 amp circuit to bath and often fed bath lights as well.

 

[goldstar]

I hardly ever encountered that on custom homes, aren't really any tract homes in the area here though I could imagine it would have been common on those. I found it a lot on manufactured homes built in the 80-90's though.

I believe you are correct. There are numerous older tract developments in my area that have this design. I believe the Code (at the time) stated that outdoor, garage and bathroom receptacles had to be on a GF circuit. So, many EC's ran a branch circuit out of the main breaker panel in the garage to the garage GFCI receptacle and then cascaded to the outlying designated areas. They were considered Code compliant at the time. I have had several people call me in this one development and say that their bathroom receptacles aren't working. I tell them to go into the garage, find the GFCI receptacle and reset it. It saves me a 1 hr. trip and the customer $$$. Don't get me wrong, I love making $$$ but I hate to go out and make $$$ by resetting a GFCI breaker. If you charge them your normal service call rate you probably won't get a call back for any other work IMHO.

 

[growler]

What change are you looking for other than the one you mentioned occurred in 1996?

Before that change I usually put bath receptacle on an adjacent bedroom circuit. (we usually ran 20 amp circuits to all receptacles and 15 amp circuits to lighting outlets only, and I still do that most the time). Since then 20 usually 20 amp circuit to bath and often fed bath lights as well.

I didn't know the change occurred in 1996. The 1996 is the oldest code book I have at present.

I really couldn't remember when they started to require a separate bath circuit. I didn't get involved with a lot of houses before the mid 1990s.

 

[ActionDave]

You are conflating GFCI with an RCD, they are not the same. GFCI is a very specific term for a PERSONNEL protective device that trips at 5mA, +-1mA. Charles Dalziel (a UC Berkeley professor) was investigating the effects of electric shock on humans and determined the amount of current flow at 60Hz that would produce a “lock” grasp response, which is what was leading to many electrocutions. He determined that in a normal human, each 1mA of current causes us to exert 10lbs of force. So the 5mA threshold had to do with how much counter force you could muster to overcome that caused by the shock in order to get you off of the connection. Contrary to popular belief it has nothing to do with how much current will stop your heart, it’s all about being able to let go of something shocking you.

Very interesting. I have never heard this before. I feel validated in my opinion that GFPE level protection is better than GFCI. I would favor GFPE on almost all circuits, I am not in favor of the huge expansion of GFCI requirements in the last couple of code cycles.

RCDs existed prior to that, but typically had a 30mA threshold, as they still do elsewhere in the world. Dalziel’s contribution was a circuit that reliably worked at 5mA and has become our standard. Outside of North America that is not the case and people use 30nA RCDs, as they were prior to Dalziel.

What is it about the US that we come up with safety regulations that are burdensome rather than workable? Is it our court system?