Ungrounded Outlets

[LarryFine]

In fact, most electronic power supplies don't even come with polarized plugs these days.

I'll be the one to say it: I dont see any safety issue with non grounded general purpose residential receps. Nearly every thing that gets plugged into them (including those "sensitive electronics") doesn't have a ground prong anyway.

That's exactly what I tell customers who ask about installing grounding receptacles "all over". It's better to run a new circuit for the audio/video system, the home office equipment, a new appliance, etc.

That provides the double advantages of assuring a full-capacity, directly-grounded supply of power to the new equipment, while relieving the existing wiring of the new, concentrated array of loads.

 

[LarryFine]

A grounding conductor assures protective device operation in case of a fault.

A GFCI device assures protective device operation in case of a shock.

 

[480sparky]

.

I couldn't have said it better myself.

 

[rnatalie]

In fact, most electronic power supplies don't even come with polarized plugs these days.

Because they don't care. The inputs are suitably isolated and usually, the first thing that happens is the power cord connects to a couple of diodes to turn it to DC. The diodes are specifically sized to protect the fuse when present

 

[ptonsparky]

I couldn't have said it better myself.

I couldn't have said it better myself.

Those inspection reports are nothing more than a tool that buyer and seller can use for price negotiations. If owner fixes the deficiencies on the inspection report then the seller has less things to use for negotiating lower purchase price when it comes to some the safety aspects as to the construction, electrical, plumbing, HVAC of the home.

The buyer can offer to pay a lower price and either fix those deficiencies or even just take it as is with the deficiencies. Lenders and insurance companies may take some that information into consideration and demand deficiencies be fixed, though it possibly still can be buyer or seller that fixes them.

Word of warning.. I’m on some kick ass pain killers the last few days and IDK what I’m argueing for or against.

To add some excitement to the day my eldest grandson said he may help me shoot the leftovers cucumbers with my .17.

 

[gadfly56]

Word of warning.. I’m on some kick ass pain killers the last few days and IDK what I’m argueing for or against.

To add some excitement to the day my eldest grandson said he may help me shoot the leftovers cucumbers with my .17.

Ehhhhhh, you might want to put off the play date with your grandson. Just sayin'.

 

[mbrooke]

Word of warning.. I’m on some kick ass pain killers the last few days and IDK what I’m argueing for or against.

To add some excitement to the day my eldest grandson said he may help me shoot the leftovers cucumbers with my .17.

What type of pain meds and what for? I hope you feel better, meds are good btw.

 

[mbrooke]

Yes, but excellent conductors at times.

Picture those old, I called them 'build it yourself' metal boxes, that you could take
apart to build different configurations.

These barely big enough boxes to get a receptacle into, were the reason the old timers wrapped tape around the receptacles and even switches.

More than once I managed to short the hot to the box. I can't imagine what I could accomplish now.

Well, now we have the original strip lights.

That BX would glow a beautiful muted red until the fuse melted and since someone had put a penny under the fuse,
well now we can add a smoke effect. Years of dust accumulation fueling the display.

How boring it must be now with all these NEC 'safety' rules.

Sadly because the NEC doesn't want to admit "we failed to define what is actually an effective ground fault current path" we get new safety rules each cycle...

 

[hornetd]

@hornetd

You seem to know a lot about the old BX so a couple of questions if you don't mind.

From what I understand, the old BX with no aluminum ground strip was use prior to about 1959 and was used with 2 wire non grounding receptacles. I have seen may houses in our area built in the mid to late 50s that have both types of BX in the same house.

Although the receptacles (two wire) did not have a ground connection obviously a short between a hot and a box for instance would hopefully trip the breaker or fuse.

What has always bugged me is i know the older BX can be a poor ground but what harm (if any) is installing grounding receptacles with the older BX wiring method?

Also I have never seen in any code book I have seen that differentiates between the two styles of BX AC cable or any mention that the older style is not approved for grounding other than speculation and hearsay.

Fire away if I am wrong!!!!!!!!!!!!!

Eddie702

The reason that the National Electric Code does not differentiate between "BX" and type A cable is that both were listed in the Underwriters Laboratory Building Materials List. The listing of an electrical assembly states the testing that it has been subjected to and that within the limits of that testing it is suitable for certain uses, in certain occupancies, at certain voltages... As BX is no longer listed by an electrical testing laboratory for inclusion in the Building Materials list it is not suitable for anything.

The prohibition against "Ex Post Facto" laws in the Constitution of these United States of America means a law cannot make something unlawful after that act has occurred. The BX is in fact dangerous and no longer listed so you cannot use any New Old Stock for any circuit energized at more than 48 volts. The NEC does not provide general regulation of electrical installations below 48 volts and an amperage that I cannot now remember. The NEC does require other named wiring methods for some types of installations. If the wiring method is not on the NEC list for applications were the wiring method is specifically named then you certainly cannot use it in a USA NEC compliant application. You can leave the existing installation in place because retrospective application of the NEC's materials acceptance language is unconstitutional. What you cannot lawfully do is make any change to the non compliant installation because the Inspector employed by the Authority Having Jurisdiction (AHJ) can, and likely will, tell you that the Installation does not have a Laboratory listed Equipment Grounding Conductor EGC. In the absence of a recognized EGC you then have to resort to a presently acceptable means of providing a EGC. Those are the means called out in the changes and revisions language of the US NEC. You simply cannot successfully argue that the inspector should accept the use of a wiring means that does not have an acceptable EGC. Acceptable to who you ask. Well at this point the local governments solicitor says "Objection Chairperson argumentative." Even the merely quasi judicial Board of Permit Appeals does not have to entertain argument against the existing state of the law. You would have to bring suite in an appropriate court that the enactment which adopted the National Electric Code by reference violates the State or Federal Constitution or if it is a prior decision of the Board of Permit Appeals that it violates that State's administrative procedures act. Either attack could called, in good faith, a tough row to hoe. That doesn't mean that such an attack never succeeds because several years ago the Supreme Court of the United States: (SCOTUS) in the Journalists' short hand known as the Phillips Code; ruled that the "Neat and Workmanlike Manner" language of the US NEC is unconstitutionally vague and therefore unenforceable at law. My point here is not to show that the code can be overturned but rather to illustrate how difficult it can be to do so.

From the perspective acquired by 45 years as a volunteer Firefighter the problem is that even in the interior of heated buildings the conductivity of the contact of the armor tape turns gradually is lost to the thin layer of corrosion between the turns of the spiral wound steel armor. If you add in any failure of the buildings shell to keep water out of the structure you have a disaster waiting to happen. The corrosion between the turns converts it from a linear conductor to a very long coil winding which has high impedance. The higher the fault current the worse the problem becomes. The impedance of that long coil of steel means it is then behaving as an inductor. That will markedly delay the current rise and thus delay the tripping or melting of the circuit breaker or fuse. I have seen; not been told nor read about, not even in the fire investigators handbooks and training materials; the char marks along the path of a run of BX; as opposed to modern Armor Clad (AC) cable; more than once.

I have made entry into a basement or attic and seen BX cable GLOWING IN THE DARK. A couple of minutes later; with the arrival of the first special service; ie a truck or squad company; the Utility Control Firefighter does their thing and the visible heating of the armor begins to cool. That doesn't mean that it has not already ignited fire in several places along the path of the installation.

As don_resqcapt19 can probably confirm that often means you are in for a true Fire Fight. You will be there for several hours pulling baseboards, opening walls and ceilings, checking for hidden fire. I can remember 2 times that a roof leak in an apartment houses flat roof was the immediate cause of the "Fire of Electrical Origin" With the "Source of Heat of Ignition" being "Electrical Failure." Both were the heating of mildly or severely corroded BX cable. I never encountered anything similar in modern AC Cable. In AC cable the aluminum strip shorts the turns to each other well enough to allow it to still behave as a linear conductor in spite of the inevitable corrosion between the turns.

That is an important distinction that most electricians are unaware of. The aluminum strip is not there to carry the fault current although it does carry some. The purpose of the aluminum strip of modern AC cable is to prevent the coiled steel armor from presenting a high impedance to fault current that will slow the flow of the fault current through the steel tape of the armor. It is still the larger cross section of the armor that does the heavy lifting in carrying the fault current quickly enough to cause the circuit overcurrent protection to open before heating and ignition of adjacent combustible materials can occur.

I demonstrated that to a class of fire cause determination students by showing them the impedance of the Ground fault current pathway of a salvaged piece of Armored Cable that had been in service for at least 20 years using an Ideal SureTest® Circuit Analyzer. I then opened the turns every 2 or so feet and cut an inch or more; however much I could easily get at; at all of those openings and then running the same test. I had also used a hair dryer between the energized conductor and the armor; all connection points being in 4 square boxes at each end of the cable; to show, by voltage drop measurement, that the Ideal SureTest® Circuit Analyzer was not somehow failing to pick up the actual impedance of the Ground Fault Current Pathway. There was only a small difference between the 2 impedance measurements. For comparison I used the smallest size of Flexible Metal Conduit (FMC) that I could lay my hands on. FMC is made exactly the same way that the armor on Type AC cable is made except for not having an aluminum bonding strip. I pulled three conductors into it but for the first test I connected the separate insulated copper Equipment Grounding Conductor at each end. For the second test I disconnected it from the box the receptacle was mounted in. so that it was not carrying the fault current in the second case. Both the Ideal SureTest® Circuit Analyzer and the Voltage drop measurement were quite a bit higher.

It was not without some trepidation that I let the 1800 watt hair dryer run until the FMC was warmer to the touch and by measurement with a non contact thermometer. Still not all of the students were convinced and especially not those who had worked as electricians before becoming Firefighters. So I upped the ante by connecting one 2400 watt resistance heaters to each of the sockets of the duplex receptacle of my test lash ups. During the break I went and got an Isolation transformer from the University Physics Laboratory. These are used to improve instructor safety during higher energy electrical demonstrations and I was now feelingg in need of increased safety. Using a 40 ampere circuit breaker for both tests the second test heated up the non bonded FMC to a convincingly hot temperature to convince my skeptics that this was indeed "a thing." Notice that even with the armor of the AC cable opened, thus breaking physical contact between the turns of the armor in several places, the bonding strip, which had also been cut so as to be discontinuous, still cut the impedance of the spiral metal tape enough so that the actual impedance wasn't markedly higher than with both the armor and the bonding strip in original condition, with the exception slight corrosion between the turns of the armor.

--
Tom Horne

 

[hornetd]

A grounding conductor assures protective device operation in case of a fault.

A GFCI device assures protective device operation in case of a shock.

LarryFine

That is certainly true. No quarrel from me.

What it appears that the code panel was doing, whether accidentally or not, was providing a type of Ground Fault Protection of Equipment although only in the case of now non compliant armored cable. It seems likely to me that a ground fault to the metal armor of "BX" cable would cause it to happily conduct the 7 milliamperes that will trip a GFCI. It is only the cloth covered original Romex, which contains no EGC of any description, that will not cause it to trip until something which is conductive comes in contact with the surface the Energized Conductor is faulted to.

For my money the US NEC should require that any replacement receptacles, in the GFI protected exception installations, be covered with a breakage resistant non conductive cover plate. Yes I know that with the products presently available that probably means Nylon cover plates but those are made by several manufacturers so I don't see a price gouging issue.

--
Tom Horne

 

[mbrooke]

I have seen; not been told nor read about, not even in the fire investigators handbooks and training materials; the char marks along the path of a run of BX; as opposed to modern Armor Clad (AC) cable; more than once.


Tom Horne

Of course. Ego is one hell of a drug. Both research and experience has taught me that any evidence which hints at mistakes or ignorance is deliberately buried. There are those that will let countless lives parish than admit they we're less wise 24 hours ago.

I think an over throw of many modern day authoritarian organizations is inevitable...

 

[mbrooke]

I demonstrated that to a class of fire cause determination students by showing them the impedance of the Ground fault current pathway of a salvaged piece of Armored Cable that had been in service for at least 20 years using an Ideal SureTest® Circuit Analyzer. I then opened the turns every 2 or so feet and cut an inch or more; however much I could easily get at; at all of those openings and then running the same test. I had also used a hair dryer between the energized conductor and the armor; all connection points being in 4 square boxes at each end of the cable; to show, by voltage drop measurement, that the Ideal SureTest® Circuit Analyzer was not somehow failing to pick up the actual impedance of the Ground Fault Current Pathway. There was only a small difference between the 2 impedance measurements. For comparison I used the smallest size of Flexible Metal Conduit (FMC) that I could lay my hands on. FMC is made exactly the same way that the armor on Type AC cable is made except for not having an aluminum bonding strip. I pulled three conductors into it but for the first test I connected the separate insulated copper Equipment Grounding Conductor at each end. For the second test I disconnected it from the box the receptacle was mounted in. so that it was not carrying the fault current in the second case. Both the Ideal SureTest® Circuit Analyzer and the Voltage drop measurement were quite a bit higher.

It was not without some trepidation that I let the 1800 watt hair dryer run until the FMC was warmer to the touch and by measurement with a non contact thermometer. Still not all of the students were convinced and especially not those who had worked as electricians before becoming Firefighters. So I upped the ante by connecting one 2400 watt resistance heaters to each of the sockets of the duplex receptacle of my test lash ups. During the break I went and got an Isolation transformer from the University Physics Laboratory. These are used to improve instructor safety during higher energy electrical demonstrations and I was now feelingg in need of increased safety. Using a 40 ampere circuit breaker for both tests the second test heated up the non bonded FMC to a convincingly hot temperature to convince my skeptics that this was indeed "a thing." Notice that even with the armor of the AC cable opened, thus breaking physical contact between the turns of the armor in several places, the bonding strip, which had also been cut so as to be discontinuous, still cut the impedance of the spiral metal tape enough so that the actual impedance wasn't markedly higher than with both the armor and the bonding strip in original condition, with the exception slight corrosion between the turns of the armor.

--
Tom Horne

Or better yet create a short circuit on some old BX or use an earth fault loop impedance tester.

Any detractor can say 'but no one is going to connect 2,400 watts of heaters line to armor, with a 40 amp breaker' Where as simple ohms law would create a situation that can not be disproven- not without some significant mental gymnastics that everyone can see.

The NFPA wittingly leaves two equations out of the NEC:

E/R=I

and

Zs=Ze+(R1+R2)

 

[romex jockey]

While no one complies with this rule, take a look at 250.114... that is a list of things that are not permitted to be connected to a circuit that does not have an EGC, and the installation of a GFCI for that circuit has no effect on the requirement in 250.114.
406.4(D)(2)(c) even has an informational note sending you to 250.144.

gawd help anyone actually ask an HI for a code ref like that Don

~RJ~

 

[mbrooke]

gawd help anyone actually ask an HI for a code ref like that Don

~RJ~

Has the NFPA ever cleared this up?

 

[romex jockey]

Has the NFPA ever cleared this up?

Evidence would conclude the NFPA could care less who publicly honors their doctrine MBrooke

~RJ~

 

[gadfly56]

Eddie702

...The prohibition against "Ex Post Facto" laws in the Constitution of these United States of America means a law cannot make something unlawful after that act has occurred. ...

This is not the sense in which "ex post facto" is employed. It is specifically intended to prevent criminalization of prior legal acts. That is, things that can get you fined or thrown in jail. And the US Constitution is about the relationship between the Federal government and the citizens, not necessarily state governments. It is true that the 14th amendment has been used to push down some of the federal rights to the states, but it has been unevenly accomplished. It is certainly possible on a state or local level to pass a law requiring that something installed be removed or something not installed be added. The likelihood is going to be inversely proportional to the cost/inconvenience to the general public. In NJ, this is most famously illustrated by the retrofit of all college dormitories with sprinkler systems if they weren't already covered.

 

[hornetd]

Or better yet create a short circuit on some old BX or use an earth fault loop impedance tester.

Any detractor can say 'but no one is going to connect 2,400 watts of heaters line to armor, with a 40 amp breaker' Where as simple ohms law would create a situation that can not be disproven- not without some significant mental gymnastics that everyone can see.

The NFPA wittingly leaves two equations out of the NEC:

E/R=I

and

Zs=Ze+(R1+R2)

Oh! So you to have met that "1 Guy" that would rather climb a tree and argue than stay on the ground and be reasonable. Aren't they so much fun to have in your class, in that not sort of way.

If I could have laid my hands on a ~100 foot long piece of "BX" I certainly would have used it. Trouble is that I don't know of anyone that demolishes buildings so gently as to leave that long a piece intact. Now that one of the nearby jurisdictions is rigorously enforcing the requirement for cable removal from the space above suspended ceilings I suppose I could get a hold of some but that rule was not in place at the time of the class I described.

I was called in by one of the presenters because I had been badgering people at the inspection office with the question about what the department was going to do about the danger of elevator shaft shunt trip heat detectors posed to firefighters. He got the impression that I was very interested in the hazards of electrical systems to firefighters which was certainly true. The demonstration was to settle an argument about one of the scenarios in their texts which asked them to defend that situation as a valid cause and origin determination. Several students didn't buy it as valid because they thought that the Over Current Protective Device (OCPD), or as they put it the dammed fuse, would prevent the fault from lasting long enough to ignite the wood of the structure. Their texts did not provide photographs of those particular ignition scenario investigations.

I wasn't exhaustive in my previous description of the demo and it is hard to know how much is worth saying. I was so honored at being called in to defend the cause and origin determination by the presenter; who was working as a fire investigator for the department, with more than a decade in that role, and was very well thought of by most of the firefighters; that I worked rather hard to put on a credible demonstration. I had Fluke current and voltage meters with peak hold on the circuit so that they could see that the current of the fault causing the heating was not enough to trip the 20 ampere OCPD that had actually supplied that circuit. What stopped the demonstration was the circuit conductor insulation softening enough to fault to each other. That tripped even the 40 ampere breaker very promptly. My only disappointment was that the un-bonded armor did not get visibly hot. In addition to the physical demonstration I had spent the half a day it took to find the files from the 2 local investigations. Those were a big help in that they contained the dates and times of the alarms. Even when I showed the students evidence photographs of the 2 local investigations some students insisted that the heating must have been caused by current from a source other than that circuit. Two of them had previously insisted that it must have been lightning discharge. Being the wise ass I sometimes can be I also brought in the official Weather Service records for the dates and times of the ignitions which showed that there had been no "Lightning On The District," to use the wildland fire suppression term, for over a month prior to either ignition.

 

[mbrooke]

Forgive me for thinking you could get ahold of BX. But I do understand what you are saying. People don't like anything that makes them think that the world which they thought they lived in is perfect, is rather not so.

 

[tortuga]

While no one complies with this rule, take a look at 250.114... that is a list of things that are not permitted to be connected to a circuit that does not have an EGC, and the installation of a GFCI for that circuit has no effect on the requirement in 250.114.
406.4(D)(2)(c) even has an informational note sending you to 250.144.

Don dont be so pessimistic, lots of us comply with that.

what harm (if any) is installing grounding receptacles with the older BX wiring method?

Its a code violation for one, so a huge liability to do so when related to a home sale.
Ill explain;
If your not bringing the building up to the current code you have to comply with 'the code in effect at the time of construction'
If you look at old pre 1968 NEC books, the armor of cable / flex was only allowed to be used as an ECG if it was 1/2 IN trade size or larger.
They actually had sizes of conduit in the table we now call 250.122
15 and 20 amp BX circuits would be 3/8 trade size so not allowed as an ECG.

In 1968 250-95 was reworded to only apply to aluminum and copper equipment grounding conductors. Using raceway or cable armor now moved to 250-57 allowing all sizes of AC cable. That was the same time they added the bonding strip to the cable.

 

[mbrooke]

Does the NEC use 400% of the breaker's handle rating as a minimum ground fault current path?