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 Post subject: Re: Better earth grounds
PostPosted: April 30th, 2020, 9:51 pm 
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Tom,

I've personally gone, to and heard from fellow employees who've gone on more, service calls for clothes dryers that spin, but don't heat. Problem is either failed heating elements or a 2-pole breaker which has only tripped on one phase. FPE is the usual culprit here and the issue is well documented with FPE breakers. I have never seen a dryer that didn't "need" the neutral connection. Haven't seen them all, nor even "most". Measured many a dryer load in a CBP, and always found greater load on one phase than the other, in addition to a neutral load.

I take your word for it that you've had experiences with dryers that do not have a neutral load.

So here's the deal: We must plan for the worst case. We don't know what dryer will be used, what future changes will occur when a new dryer is purchased, etc. So we always provide a neutral separated from ground, even if the present load doesn't need it. Exactly like the case with your pulsed xenon lighting. If we are installing a NEMA receptacle, we follow Code and Listing rules for that device, because ANYONE can come along after the installation and connect ANY appliance to the receptacle that has a matching cord cap. That person has every right to assume that conductors are connected correctly, not for one specific device.

A similar issue comes up with motor loads. We size wiring and overcurrent protection according to Code tables of motor loads. The ACTUAL motor used for the application will most likely have a lesser nameplate load. But that motor will eventually fail and be replaced with another (assuming same size to drive the same machine). The repair person may use the cheapest Dayton motor possible because his customer wants to spend the least money possible. That replacement motor will likely have a higher nameplate FLA than the original.

Again, we have to assume the worst. We supply the biggest circuit that an "X" horsepower motor could require. The overload protection is tailored to the specific motor nameplate information.

So I understand that it seems like the Code is "selling" you something you don't need, but the fact is, the installation is not designed for you, it's designed for you and whatever future owner/tenant comes along with whatever future requirements may exist.


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 Post subject: Re: Better earth grounds
PostPosted: May 1st, 2020, 8:39 am 
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Stuart I totally agree with you on planning for future development. That is why I'm specifying a NEMA 14-50R receptacle in my garage for the electric car charger. It is a 4 wire connection even though many of the car chargers only have 3 wire plugs. Here are photos of the NEMA 10-30P plug on my current dryer which has largely been superseded and the newer NEMA 14-50R


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 Post subject: Re: Better earth grounds
PostPosted: May 1st, 2020, 8:40 am 
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Location: Parkville, Maryland
Stuart Polansky wrote:
Tom,

I've personally gone, to and heard from fellow employees who've gone on more, service calls for clothes dryers that spin, but don't heat. Problem is either failed heating elements or a 2-pole breaker which has only tripped on one phase. FPE is the usual culprit here and the issue is well documented with FPE breakers. I have never seen a dryer that didn't "need" the neutral connection. Haven't seen them all, nor even "most". Measured many a dryer load in a CBP, and always found greater load on one phase than the other, in addition to a neutral load.

I take your word for it that you've had experiences with dryers that do not have a neutral load.

So here's the deal: We must plan for the worst case. We don't know what dryer will be used, what future changes will occur when a new dryer is purchased, etc. So we always provide a neutral separated from ground, even if the present load doesn't need it. Exactly like the case with your pulsed xenon lighting. If we are installing a NEMA receptacle, we follow Code and Listing rules for that device, because ANYONE can come along after the installation and connect ANY appliance to the receptacle that has a matching cord cap. That person has every right to assume that conductors are connected correctly, not for one specific device.

A similar issue comes up with motor loads. We size wiring and overcurrent protection according to Code tables of motor loads. The ACTUAL motor used for the application will most likely have a lesser nameplate load. But that motor will eventually fail and be replaced with another (assuming same size to drive the same machine). The repair person may use the cheapest Dayton motor possible because his customer wants to spend the least money possible. That replacement motor will likely have a higher nameplate FLA than the original.

Again, we have to assume the worst. We supply the biggest circuit that an "X" horsepower motor could require. The overload protection is tailored to the specific motor nameplate information.

So I understand that it seems like the Code is "selling" you something you don't need, but the fact is, the installation is not designed for you, it's designed for you and whatever future owner/tenant comes along with whatever future requirements may exist.


Again -- to make Stu's point perfectly clear -- regarding the National Electric Code and the International Electric Code -- these documents were not developed by a bunch of "suits" sitting around a conference table making arbitrary decisions. Those codes were developed over many decades as a direct result of failures experienced and reported. These failures were either an operational issue as Stu explained or a fire event. Stu also mentioned Federal Pacific (FPE) that went out of business because of a class-action suit. Their Stab-Loc circuit breakers either false-tripped, came loose internally, or just did not trip at all from an overload (a fire event in the making). They never submitted their products to the Underwriters Laboratory for testing and certification -- they simply printed their own U.L. labels and stuck them on product. Any of you out there with old houses may still have these Stab-Loc products.

To simplify -- the bottom line of codes is to protect the wiring (fire events) and and to provide human safety in terms errant ground currents that CAN kill. Ground Fault and arc-flash devices were not meant to run up $$$, they were meant to eliminate injury and death either from electrocution or fire -- as but two examples.

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 Post subject: Re: Better earth grounds
PostPosted: May 1st, 2020, 8:51 am 
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To further reinforce what Walt has said about fires it is interesting to note that the National Electrical code is produced by the National Fire Protection Association and is one of their many codes.


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 Post subject: Re: Better earth grounds
PostPosted: May 1st, 2020, 9:29 am 
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tomp wrote:
Stuart I totally agree with you on planning for future development. That is why I'm specifying a NEMA 14-50R receptacle in my garage for the electric car charger. It is a 4 wire connection even though many of the car chargers only have 3 wire plugs. Here are photos of the NEMA 10-30P plug on my current dryer which has largely been superseded and the newer NEMA 14-50R


I know you meant 14-30R, just being a dick. Hey, you'd do the same for me! :lol:


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 Post subject: Re: Better earth grounds
PostPosted: May 1st, 2020, 9:38 am 
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Location: Parkville, Maryland
tomp wrote:
To further reinforce what Walt has said about fires it is interesting to note that the National Electrical code is produced by the National Fire Protection Association and is one of their many codes.


YUP! I just received the 2020 code for work and attended a seminar that focused on safety issues. I was surprised as to how many safety rules changed with regards to main electrical rooms in large buildings.

I imagine that if you get enough electricians hauled away in a stretcher -- the requirements change.

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 Post subject: Re: Better earth grounds
PostPosted: May 1st, 2020, 10:56 am 
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SoundMods wrote:
I imagine that if you get enough electricians hauled away in a stretcher -- the requirements change.

Not just electricians on stretchers.

When Tom P. Walt and I were little kids, the standard used to ground an electrical service in a single family home was by connecting to the cold water pipe. No supplemental grounds were used. In that time frame, cold water pipes would have been galvanized pipe (with yummy lead inside) or copper tubing. So, the electrician installed a GEC (grounding electrode conductor) from the panel to the most convenient water pipe.

Three things happened. 1) A plumber repaired or replaced a section of pipe, maybe made a new tap for a new plumbing fixture. He shut off the water and cut the pipe in the basement ceiling over his head. He gets wet, and when he separates he pipe between his two hands, he becomes part of the service ground. Zap, one less plumber. 2) The connection was made to a hot water pipe and a new water heater was installed with non-metallic piping inside. No service ground in the house. Very bad for occupants. 3) That nasty old galvanized piping gets replaced.......with PVC or PEX. Again, no service ground in the house. Danger Will Robinson.

So, Code evolves, as Tom and Walt pointed out, due to dead plumbers and shocked, or worse occupants. Now we connect to cold water within 5' of the point of entry of piping to the house 250.68(C)(1). Where I work, we try very hard to make the connection closer to the point-of-entry than that. Also we try to connect ahead of the water shutoff whenever possible. AND we are required to use at least one ground rod (PG County requires two ground rods), so we minimize the chance of harming a plumber or homeowner working on household piping.


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 Post subject: Re: Better earth grounds
PostPosted: May 1st, 2020, 12:05 pm 
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Joined: July 24th, 2015, 4:17 pm
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Location: Parkville, Maryland
Stuart Polansky wrote:
SoundMods wrote:
I imagine that if you get enough electricians hauled away in a stretcher -- the requirements change.

Not just electricians on stretchers.

When Tom P. Walt and I were little kids, the standard used to ground an electrical service in a single family home was by connecting to the cold water pipe. No supplemental grounds were used. In that time frame, cold water pipes would have been galvanized pipe (with yummy lead inside) or copper tubing. So, the electrician installed a GEC (grounding electrode conductor) from the panel to the most convenient water pipe.

Three things happened. 1) A plumber repaired or replaced a section of pipe, maybe made a new tap for a new plumbing fixture. He shut off the water and cut the pipe in the basement ceiling over his head. He gets wet, and when he separates he pipe between his two hands, he becomes part of the service ground. Zap, one less plumber. 2) The connection was made to a hot water pipe and a new water heater was installed with non-metallic piping inside. No service ground in the house. Very bad for occupants. 3) That nasty old galvanized piping gets replaced.......with PVC or PEX. Again, no service ground in the house. Danger Will Robinson.

So, Code evolves, as Tom and Walt pointed out, due to dead plumbers and shocked, or worse occupants. Now we connect to cold water within 5' of the point of entry of piping to the house 250.68(C)(1). Where I work, we try very hard to make the connection closer to the point-of-entry than that. Also we try to connect ahead of the water shutoff whenever possible. AND we are required to use at least one ground rod (PG County requires two ground rods), so we minimize the chance of harming a plumber or homeowner working on household piping.


You should see what I've seen on many buildings (to bring home a point of where to install ground connections) -- Alternate building grounds fastened with a steel clip on a copper feed on the building side of a flange. Another one I have fun with is a ground clamp on the rubber coating of modern water service entrance piping. The ductile-iron potable water in-ground piping in new construction is now coated with a rubber mastic or shrink wrap so that the pipe at least lasts the life of the building. The typical electrical contractors will clamp to that rubber on the building side of the flange. WTF?!! The ground connection should be CAD-welded to the street-side of the flange -- not the pipe on the building side. Now here is where lobbying comes in. The NEC originally required a ground resistance (D.C.) no greater than 25-ohms. That flies in the face of reality when contractor ground testing equipment uses A.C. The insulated pipe is in effect a giant capacitor so the code was changed to impedance (A.C.). I am not even sure that is valid at all. It is what it is.

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 Post subject: Re: Better earth grounds
PostPosted: May 1st, 2020, 4:24 pm 
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Posts: 259
Location: Highland, MD
Total aside:

I use the NEMA 14-50R for my air compressor!

I've violated my warranty because they require me to use the supplied #10 crimp connectors on the inlet range cord, which has a pair of #8s and a pair of #6 wires. I clamped the necessary wires into the pressure switch instead of cutting strands off of the wires until they fit into the crimp connectors.

I may be wrong, but I like my solution better.

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 Post subject: Re: Better earth grounds
PostPosted: May 1st, 2020, 6:43 pm 
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Just got back from a meeting with my builder in PA re the new house. Was glad to see the box for the dryer has 4 wires, not 3. My guess is that the electrician will install a 14-30R receptacle because the LG dryer cord appears to have a 14-30P plug. Also, the house ground is to two rods with copper wire connecting them. The meter box also has two leads because it is a 400 amp service and is going to two boxes. Each is rated at 200 amps. One is a utility only service rated load center and the other is the service rated generator transfer switch that feeds the second load center.


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