Code versus safe

[-klb-]

I agree that you can find quite a bit done wrong by qualified electrical contractors. The city park has a 400A panel, in an outdoor enclosure, with conduit to 7 different locations through the park, and seasonal use outlet panels that go with them, and a total of 36 20A GFCI outlets, each on their own circuit. This was done 3 years ago, for about $30,000. I spent quite a bit of time over the first two years identifying and complaining about significant safety issues, and getting the contractor to fix them.

This year, we were still finding more issues with their original work, and fixing them on our own.

But, even scarier is the stuff done 5 years ago, on the back of the fire station. Also by a licensed electrician. We are continuing to improve that as well.

[KStatefan]

I really enjoy threads like this. I do not have the expertise that some of you have and learn something from these threads. I am always referring to NFPA 70 and NFPA 70E at work to make sure things are being done correctly.

[Chris B]

How does the shared neutral work with the GFCI? It looks to be like you have 2 different hots on a shared neutral. If one controller dims or the load changes why does it not trip the gfci? Thanks Chris

[-klb-]

If you are doing something like putting a sub panel, like a hot tub panel on 220V GFCI breaker, it is a single 220V circuit with neutral. The 220V GFCI has connections for both hots, and also passes neutral through the breaker, just like a 110V GFCI passes neutral through the breaker. Then the hot tub panel may have multiple breakers, at 220V, and 110V.

Or, if you are using GFCI outlets, again, as a sub panel off the 220V circuit, the GFCI protection only extends from the GFCI outlet onward. So again, the 220V circuit with neutral, which allows it to support 110V loads, is not a problem with GFCI..

And again, these cases are not shared neutral, as the neutral is only serving one breaker, thus one circuit.

[De Trommelslager]

Chris B wrote:

How does the shared neutral work with the GFCI? It looks to be like you have 2 different hots on a shared neutral. If one controller dims or the load changes why does it not trip the gfci? Thanks     Chris

Here is a picture that shows what is heppening in the GFI and how they can be wired with a common neutral.



In the image, the neutral wires (gray in this picture) are tied together. The neutral only carries the unbalanced load. So, if the black phase had 13A and the red phase had 12A, the neutral would only carry 1A - the unbalanced load. Logic would dictate otherwise and it would appear that the load on the neutral would be 25A.

Where one can get into trouble: if both of the wires feeding these two receptacles were on the same phase, then the neutral would carry the sum of both receptacle's loads because there isn't a phase to balance to. Both phase wires (if on the same phase) are on the same plane.


To answer your question, the GFI doesn't care how much current is being drawn by the load; that is the circuit breaker's job. The GFI is just making sure that what is going out is coming back, and if not it opens the circuit.

A GFI works by comparing the current on the hot and neutral. If there is an unbalance of 4-6mA (.004A-.006A), then the GFI opens the circuit to stop the flow of current. And that isn't a lot of current!



Reality check...

Before ditching the GFIs (not saying anyone is here, just a blanket statement), take a moment to think about their importance to what we are doing. We light our homes for people to enjoy. Those blinky lights will bring "Curious George" into your yard sooner or later, and "George" will have to touch something. If that something had a voltage potential and George closed the circuit, in could mean a tripped GFI, or an obituary. And that obit would certainly take the joy out of the lights!


Some quick numbers; the typical human male starts to feel a shock at 5.2mA-6.2mA (.0052A - .0062A). The threshold of muscles not being able to let go is between 16mA-20mA (.016A - .020A). That single 125V 15A circuit can deliver 1,000 times enough current to kill a person!

That's why GFIs are so important.



Chris, hopefully that answers your question.

[beeiilll]

This has turned into a very informative and useful thread on the GFI issue and their importance with being safe.

I think that with the current progress on electrical standards that it will also become very important to discuss the usage of AFCI style breakers with outside lights as well.

AFCI breakers are becoming code required for new home construction and don't get a lot of attention yet but will as more people get into using the circuits inside their homes to power outside lighting and run cords out through windows/doors.

The name AFCI stands for:
Arc Fault Circuit Interrupter (http://en.wikipedia.org/wiki/Arc-fault_circuit_interrupter) which basically means that:

"AFCIs resemble a GFCI/RCD (Ground-Fault Circuit Interrupt/Residual-Current Device) in that they both have a test button although it is important to distinguish between the two. GFCIs and RCDs are designed to protect against electrical shock while AFCIs are primarily designed to protect against arcing and/or fire."

These are not intended to replace a GFCI by any means but since they are meant as a means to determine an Arc Fault condition, they can be a problem with an outside lighting circuit. If you had a plug laying in a puddle and the water caused a "short and/or a subsequent arc", an AFCI breaker/receptacle should trip and stop power.

The latest revision to the NEC code now requires Arc Fault breakers on new home construction.
The early versions of the arc fault breakers were prone to false trips and could also be forced to trip by poor wiring techniques/construction methods and were problematic for installers (read I tore out some hair while working with them in the early stages of their usage!) but they have become better.
But at a cost of $35 to $50 EACH for an AFCI breaker, they are not a cheap option to go and replace them if they are suspect by any means.

I hope De Thrommelslager can chime in give a review/ overview on his take on AFCI's as I am sure that we will see problems coming to light with them as more people try to use circuits that are protected with them for lights.

Bill


I also had someone PM me and ask me why I do not quote code references when answering things on here? I don't quote NEC or other references since the "information" contained here on the forum and in its stored archives can "outlive" codes by a long time.
The NEC codes are constantly changing and being updated as new requirements and technologies are introduced and refined, therefore the actual codes are not always applicable for all as well as different states have varying codes that can supplement or oversee other codes. That makes it too hard to provide a catch all and it is better to reference people with the:

Check your local codes for anything you do!!

Hope that explains my position on providing actual code numbers/references.

[De Trommelslager]

beeiilll wrote:

I hope De Thrommelslager can chime in give a review/ overview on his take on AFCI's as I am sure that we will see problems coming to light with them as more people try to use circuits that are protected with them for lights.

Well, let me do my best. I don't have much experience with them, so here it goes... The majority of my electrical knowledge lies in commercial/industrial applications, and AFCI isn't widely used in those environments.


AFCI (Arc Fault Circuit Interrupter) breakers sense arcing in a circuit and will trip when an arcing event is sensed. Back in the early 2000's, they were required (NEC) in new residential construction for certain areas (bedrooms I believe). In the late 2000's, their required use was expanded in more areas of new home construction.

An AFCI breaker has circuitry built in that monitors the circuit for the signs of arcing events. When an arc event happens in a circuit, the voltage and current flow are effected and there are spikes and dips. Getting into all of the science of arcing is way beyond this thread, but the AFCI is monitoring the load for the patterns associated with arcing events.

When the AFCI was first introduced, there were problems with the technology and resulted in lots of nuisance tripping events. Breakers would trip because of plugging in a cord and drawing an arc, or motor arcing while running, that sort of thing. For the electricians installing and servicing them, they were a pain in the posterior. Manufacturers didn't have the benefit of real world application and trending, so they did the best they could in designing them. Over the past decade, the technology has improved and AFCI breakers are much better.

There are a couple of different types of AFCI breakers available. The standard AFCI breaker provides parallel arc fault protection, meaning it senses arcs between hot and neutral, neutral and ground or hot and ground. A combination AFCI breaker also senses series arc faults within a circuit, such as a broken wire arcing across the a gap.


And here's a potential trap... There is a misconception among many that an AFCI combination breaker also contains GFI protection. That is false, an AFCI does not protect from ground faults. GFI protection can be used with an AFCI breaker, though. Common method is an AFCI breaker serving a GFI receptacle.


As for powering our lighting displays with AFCI protected circuits, I am not sure how the AFCI would interact with the different lighting effects that the LOR equipment is capable of. Without looking in the insomnia curing code book, I believe the AFCI protection is not required for outside receptacles, or receptacles in unfinished areas. GFI protection is required for outside receptacles, though.

Since the LOR effect handling is electronic, there might be some patterns in the load(s) that could give a false indication and cause an AFCI breaker to trip. Or it may not at all, again I am out of my area of knowledge there. Surely there are some folks that are using AFCI on their displays (or have attempted to), and if so please chime in. I would like to hear what your experiences have been.

Wish I had more insight, but I don't.

[beeiilll]

Thank you for the reply on this.
Now that I know you are more geared towards the commercial end of things, I will try to remember that.
Although you have a much better way of explaning things than I will ever be able too. I'm too old and set in my ways to explain anymore other than the "If you stick your finger in there, you will probably get hurt".

Maybe I will install a couple of AFCI breakers in my sub panel and run some things over the summer this coming year and see how they react to the "flashy/blink" lights out there.
Couldn't hurt to see how they behave both directly and as feeding a GFI receptacle.

And as you stated, the AFCI breakers have improved dramatically in the last couple of years as well so they are much better as sensing and reacting to problems than they were.

[De Trommelslager]

Aside from installation methods and materials, most things translate between commercial/industrial and residential applications. AFCI is one area that my exposure has been limited, and the Smart House system is another. With a little research, any of it can be understood though.

The AFCI experiment would be an expensive trial. The breaker cost for a pair is half a controller. Or eight strings of lights. Or a leaping arch. Or five mini trees. Or materials for custom cords. Or half a mega tree. Or... Help me, I have the LOR sickness!

Seriously, if you do the ACFI experiment I would like to know how it goes for sure.

[steve synek]

beeiilll wrote:

Great discussion on the electrical topic here.

Steve synek:

I should have been clearer in my post on Underwriters and UL as they are one and the same. An Underwriters inspector will give the job a UL listing which just means a better "quality" of workmanship and adherance to codes above a regular electrical inspection based on the NEC codes.

Please don't anyone jump on me for that statement but I have found that as Dr Trommelslager noted:
"Now, as with every profession, there are inspectors out there that don't have any business inspecting electrical installations".
I too have found a few inspectors that will do the NEC based inspections and just want their money more than wanting to look (and some don't even look) at the job. I will not accept that as it is my name on the job and I take a lot of pride in my work and I want it to be correct as well as safe as possible for the owner.

Jump, Jump, Jump on Bill..........................LOL

Are you sure that it's a (better) listing? What critteria are they using? My understanding is that a field inspection by UL verifies that the installation or product is in compliance with one or more of their standards. Sorry to get technical on the terms, but that's what my job requires.

I can not speak for other inspectors, but my training has lead me to operate under the premise- Inspect the installation for code compliance. Do not play the "what if?" scenario. There is no code violation for mixing #12 &14 on a 15 amp circuit. For me personally, I get offended when non code issues are cited as violations. It is not fair to anyone to enforce my will or better building practices. I will get persecuted in a court of law here in Ohio if I step outside the boundary of the minimum requirements. I can allow better but not enforce the issue. If changes are made to a system after inspection, that is not something under my control. ( And to side track this issue further, here in Ohio, I have no right to approve or disprove anything-tho in fact that is how the system works. I give out red and green stickers everyday).

Please note: I am not jumping, just softly talking!!!!! LOL

Steve

[De Trommelslager]

The important thing to remember is the the NEC is the minimum requirement. Nothing says you can't build in added safety!

As for a NEC code inspection versus an UL inspection; it is the authority having juristiciton's requirements that the installation has to satisfy. Building to NEC, then use NEC standards; building to UL, then use UL standards (though that is a new one for me). It's really that simple.

If you work at a government installation, the code made not even apply. A nuclear power plant is one example that comes to mind. In those cases, there is a team of inspectors (electrical engineers) that look at the installation in fine detail and determine if it meets requirements.

A given facility may have its own regulations that must be followed as well, those being facilites that have minumum standards that exceed NEC. An example is one large corporation that I have worked at in the past requires all 20A circuits serving computer loads must have at least a #10 dedicated neutral, a #10 ground and a #10 dedicated ground. While that standard isn't in the NEC, we had comply with the facilities specifications.

In Texas, each city can have its own set of standards that must be followed. One city in the D/FW area requires residential structures to be wired with conduit (EMT) and wire. No romex allowed! The adjacent city may require that the minimum grounding electrode be 4/0 (none that I know of, just a hypothetical example). It all depends on where you are and what standards you have to meet.


I am unfamilier with the UL standards, so I can't speak on those. However, the NEC has been in existence for decades, and a testament to its safety can be summed up by going to a third world country. Look at their power systems and compare them to ours (NEC). :shock:

[beeiilll]

steve synek wrote:
[quote
Jump, Jump, Jump on Bill..........................LOL

Are you sure that it's a (better) listing?  What critteria are they using?  My understanding is that a field inspection by UL verifies that the installation or product is in compliance with one or more of their standards. Sorry to get technical on the terms, but that's what my job requires. 

I can not speak for other inspectors, but my training has lead me to operate under the premise- Inspect the installation for code compliance.  Do not play the "what if?" scenario.  There is  no code violation for mixing #12 &14 on a 15 amp circuit. For me personally, I  get offended when non code issues are cited as violations.  It is not fair to anyone to enforce my will or better building practices. I will get persecuted in a court of law here in Ohio if I step outside the boundary of the minimum requirements. I can allow better but not enforce the issue. If changes are made to a system after inspection, that is not something under my control. ( And to side track this issue further, here in Ohio, I have no right to approve or disprove anything-tho in fact that is how the system works. I give out red and green stickers everyday).

Please note: I am not jumping, just softly talking!!!!!  LOL

Steve


Sticks and Stones may break my bones, but whips and chains excite me!!

Go ahead and jump away, I have pretty wide shoulders and don't fear it in the least - LOL

If you do a "proper" inspection Steve, then my hat is off to you and good for you.
My "personal" experience is that the UL inspectors take their jobs more seriously and will do a complete inspection for me versus a standard everyday electrical inspector who many times will hand me a sticker out their car window as I pass the check to them for the inspection.
That is fine for many and as long as I do my job right should not be a problem. BUT - I would rather have an inspector DO the inspection, not just take my word for it. I am confident in my capabilities at this but the inspection is supposed to make sure that I have not made a mistake, not just pick up a check and run.

The UL inspector follows the NEC for his guidelines but I find that they will actually measure the horizontal distance of a light fixture from a tub and verify that the codes are followed.

That is my only reason for using them over a regular inspector.

I had a job where someone else put in the service entrance and had one of the hot wires and the neutral switched in the meter can!! The regular inspector had "inspected" this installation and written it up as okay? I don't think so. That was certainly not in compliance with the codes. Luckily I was working on the house when the power company came to hook it up and showed it to me. I fixed it and they did the hook up.

I know that the UL inspector will look and make sure and that is why I use him instead.

I will not take a chance on my work causing someone harm when it is so simple to just use an inspector that cares and will check. It is for my safety as well as the customers as well as I paid for an inspection, not a "here's your sticker - where's my check" type.

The UL inspector makes sure that there is code compliance for me, that is all and I want that on my work. But he also helps me to make things just a little better than the other guys and people like my work as I am more strick and careful.

I could just stick to the letter of the codes and let a lot of things go by, but my word and my work is who I am and that is more important to me than being able to say I got done 2 hours quicker by hurrying or not worrying about the little things that will make my jobs stand out and make me proud of what I do.
Old fashioned by all means but I was raised to do the best I can for my pay. I don't make a lot since I am slower than these other guys but I sure do a much nicer job (at least that is what the inspectors and the customers tell me anyway).

So hopefully that explains this okay? And yes the UL inspection just verifies that it is in compliance with their standards (NEC first, then UL).

Oh and one more thing. LOL

Almost all the other electricians around here will NOT use the UL inspection service because their work will fail (and they know it).
Maybe I am somewhat arrogant but I like the fact that I can do a better job than the other guys

[KStatefan]

"And here's a potential trap... There is a misconception among many that an AFCI combination breaker also contains GFI protection. That is false, an AFCI does not protect from ground faults. GFI protection can be used with an AFCI breaker, though. Common method is an AFCI breaker serving a GFI receptacle."

This is very common.