Double lugging

Originally Posted By: Dennis Bozek
This post was automatically imported from our archived forum.



Joe,


My answer would be no because a neutral is a current carrying conductor where a ground is not. Also the neutral bus bar is not rated for double lugging. Typically the largest gauge wire you can put into a neutral buss is 4 gauge and it fits quite tightly. Regardless of that fact though, I do not ever double lug any wires other than a ground and a ground purely because grounds are not current carrying conductors. Double tapping and lugging can create hot spots on breakers and neutral bars if not tightened to the correct torque and especially if two different size conductors are used. This is especially true if aluminum conductors are used and they are not protected against corrosion with De-ox. Because the hot and neutral wires are current carrying conductors, the chance is then greater for potential hot spots. If the double tap or lug becomes lose, it begins to arc. As it arcs it builds up carbon. Carbon is then resistance and with the more carbon buildup the more difficult it is for the conductor to make contact....thus increasing the current. End result can be the breaker tripping because of the loose conection (excessive current exceeding the rating of the breaker), or signs of overheating such as discolored wires, melted wires, etc, or worse yet...fire! I have often double lugged ground wires and have yet to fail a EI inspection for it. You will never see a panel done by me though that has double tapped hots or double lugged neutrals. I just won't do it....to me it is a safety issue.

I carry a temperature sensor, which is a battery operated laser that can measure temperatures up to 2000 degrees Farenheit. I use this device when inspecting and/or troubleshooting electrical panels. One can measure the temperature at the point of connection in the breaker and at the neutral buss. These temepratures should be relatively close to one another. Some might be a tad higher than the rest due to different types of loads causing more current thus creating more heat (power). I think if a panel that utilizes breakers rated for double taps is questionable, this would be an excellent way to determine if the connection is safe or not. But again as I mentioned in my previous post...I always put a single wire on a single connection.

Another example of what loose connections can do is sometimes seen in a wirenut, that does not have all the wires properly "tied" within the wirenut. What typically happens is the connection made by the wirenut becomes hot, thus causing either a loose or intermittent connection. In this example, as the wires try to make contact, they buildup excessive current doing so and promptly will melt the wirenut. The next time I see a melted wirenut or melted wires at a breaker due to double tapping, I will post the pics on this BB. So my point is....double tapping might be acceptable for some breakers rated for such....but it is not a good rule to follow. Double lugging anything other than 2 ground wires is never an acceptable practice by me.

Sorry for the long response Joe but sometimes I am long winded....just ask Russ lol.


--
This information has been edited and reviewed for errors by your favorite resident sparky.

Originally Posted By: Dennis Bozek
This post was automatically imported from our archived forum.



Also Joe…one should never splice in a electrical panel or should they use the panel as a feed through for other panels. The panel is not a junction box. Splicing wires together in a panel and then feeding the spliced wires to a breaker on a single conductor is not a recommended practice. Let’s say you splice 3 circuits that are #12 wire together and then feed those spliced wires to a breaker utilizing a single # 12 wire. Let’s say that wire #1 is pulling 8 amps, while wire #2 is pulling 6 amps and finally wire # 3 is pulling 10 amps. At the splice there is a total of 24 amps and worse, at the single #12 wire there would be a combined current of 24 amps, thus exceeding what the wire is rated for. In this case as well, the 20 amp breaker will most assuredly…trip. In any case though, splices are not allowed in an electrical panel. If the wires are too short to reach the breakers, the splices must be made outside of the panel, such as in a trough or 4 square box but again caution must be taken for if the combined current of the splice exceeds the wire ampacity of a single conductor used to feed a breaker for the spliced wires, you will have a overlaod condition on that single conductor and/or breaker.



This information has been edited and reviewed for errors by your favorite resident sparky.

Originally Posted By: nlewis
This post was automatically imported from our archived forum.



Dennis,


Is there a code reference for not allowing wire nuts in a panel? I see it all the time, approved by the AHJ. I've never found a mention of it in the NEC.


Originally Posted By: jfarsetta
This post was automatically imported from our archived forum.



Dennis,


We've been 'round this one for the past year. I originally thought as you do, that splicing in a panel is a no-no. No one was ever able to find reference to it, though, in the NEC. Joe Myers and I had this same discussion on this board less than a year ago. We also had a licensed sparky from Washington State chime in. Again, no definitive answer, other than an undesireable practice to some. Alternately, the NY Board of Fire Underwriters, the electrical AHJ in this area of NY State, says it's fine to splice within an electrical panel. So, how do we call it a defect if we're going to be overridden by both the local electricians and the AHJ?

Joe F


Originally Posted By: jfarsetta
This post was automatically imported from our archived forum.



My previous post chimes in exactly wit Neal’s comments. Neal inspects in NJ, while I inspect in NY. So, there are at least 2 separate and distinct AHJs involved, in two differing states, which follow the same thought process; that is, that splices are allowed in electrical panels.


As to your example of the 3 wires carrying a combined amp-draw of 24, how could this be real? The breaker is not smart enough to know how many wires are connected behind it. For that matter, its dumber than a stick. It trips due to heat, not current load. As a 20 amp breaker has a duty rating of 80%, it would trip after tolerating a load (heat generated) from approximately 16-amperes of load. So, how could the 3 wires ever put a 24-amp load on the #12 they connect to? The current flow through the #12 is governed by the breaker it connects to, and nothing more. This is why it is against code to connect a #14 to a 20-amp breaker; the breaker would fail to trip before the wire heated up...

This is a legitimate question. I'm not trying to be a wise a$$ here. Your analogy is the same as plugging 15 hair dryers into a single circuit. Either way you cut it, the breaker would trip before the wire burned. You've described a simple parallel circuit, with all amperage ratings matched. The combined draw overloads the breaker. What am I missing here? Isn't this why junction boxes are used?

Joe F


Originally Posted By: jremas
This post was automatically imported from our archived forum.



What about when an older panel is replaced and the existing wires are too short to make the lugs for the neutral, ground and breaker? Can you splice then? Do you have to install a junction box upstream then run new wire to the panel from the junction box? I need some answers… Also, how about this: I saw a replacement 100amp panel (brand new) that did not have a separate grounding bar installed. All of the receptacles in the home were still 2 wire with no ground. The ground wire to the outside was off of the neutral bar. I assume the neutral bar should have had a bonding screw, but why would a ground bar be installed if there were no grounds because the old BX was never updated? Every single outlet in the home was a 2 prong. Lets hear some expert opinion, fact and advice on this one…






Jeff Remas
REMAS Inspections, Inc.
Northeastern PA & the Poconos
www.NEPAinspector.com

570-362-1598

Originally Posted By: Dennis Bozek
This post was automatically imported from our archived forum.



There is nothing that I know of, that specifies that splices are not allowed in a panel. This is just general knowledge that I have come across after being inspected by probably a bazillion EI’s in my time. The EI’s of some municipalities tend to frown on splices. Whenever I do a panel cheange and/or upgrade, if the wires coming into a panel are too short to make a breaker, I extend the wires by splicing them in a 4 square junction box or a trough, before re-entering the panel with them. EI’s love to see this and I really don’t know why. Nevertheless, it has always been a rule of thumb, to make all splices outside of a panel. A junction box is the most likely place for an electrician to look for splices when troubleshooting and typically the panel is the last place they would look. Another aspect to look at is the amount of wires in a panel. If there was a splice in the panel and then it was covered by 20 or 30 wires…how difficult would it be to inspect the splice or troubleshoot it or to even see it. It is just a common sense approach to splicing in the panel and probably why most EI’s frown on it. I have at times made a splice or two in a panel and I think most electricians would admit they are guilty of it as well. However, if I need to splice a wire in a panel I make sure it is visible and accessible.


I am not one to quote specific articles in the NEC when it comes to these types of questions. I know the code and I am a licensed journeyman electrician in Ohio. My advise and knowledge is based on 34 years of experience and very, very few failed inspections by city and state electrical inspectors. It is my job on a daily basis to know how something is installed and why it is installed that way. On the average I take up to 10 to 15 hours of code classes a year. I can find most of the articles and I could quote the article itself here, but that takes to much time to do for something I practically know by heart. In fact, I very seldon refer to the code book, unless it is something I am totally unaware of in regards to installation.

I rate a continuous loaded breaker (3 hours or more of continuous use) at 35% of its rating (ie. a 20 amp breaker @ 7 amps). In a contiuous use situation, because there is constant current flowing through the breaker, heat does become a factor. The breaker will get quite warm but it will tend not to fail from heat. A breaker fails because of over current. I have seen 20 amp breakers loaded to 18 even 19 amps in a house with no problems. Granted this is rather high and something should be done in this case to relieve some of the load on this circuit. Nevertheless, the breaker will not trip unless the maximum amount of current that the breaker is rated for is exceeded.

In a commercial environment, where lighting can at times be run 24/7, most contractors here will design the build so that no single breaker will be drawing more than 35% of the given rating of the breaker at any time over 3 hours of use. This keeps the breakers somewhat cool. If the circuit was designed for 80% on a continuous load, that panel and those breakers would be very hot, but typically would not trip. If the breaker had loose connections on it, such as in a double tap, the breaker does get warm but it does trip because of the warnmth of it. It trips because of the current produced by the loose connection. Again, as a circuit tries to deliver power, if the connections are loose, arcing will happen. As the wires arc to make contact to the breaker they are connected to, carbon builds up on the loose connection thus making it harder to make contact. The carbon then causes more resistance thus increasing the current. When the breaker reaches the point that it is saturated with the amount of current draw expected of it,

In a instantaneous situation such as a short circuit, the breaker never has enough time to heat up. It trips instantly due to the amount of current that is is sensing on the circuit. A breaker does not trip because of heat. It trips because of an over current situation.

Typically, and whenever feasible, when I size a circuit, I always try to run a wire rated for more than the breaker. For instance, in a 15 amp circuit I would run 12 gauge wire. In a 20 amp circuit I would still run 12 gauge because according to the code, 12 gauge is really good for 25 amps, even though in a residential environment, it is common to refer to #12 for 20 amps and #14 for 15 amps. Hardly anyone uses 14 gauge wire anymore for new construction and those that do only do such to save money, as in the case that they are wiring several houses. 14-2G romex is a lot cheaper than 12-2G romex.

If a breaker has been heated up due to a high amount of current running thru it for long periods of time, it is possible for the breaker to fail eventually, due to the heat. But again, the true reason why a breaker trips is due to exceeding the rating of the breaker.

If I hooked 15 hair dryers into the same circuit and turned them all on (man thats a lot of hair to be drying all at once), the breaker would trip instantly and not because of heat but because of CURRENT. If each hair dryer pulled 5 amps, then 15 of them at the same time would be 75 amps. If connected to a 20 amp breaker, by the time I turned on 5 hair dryers, the breaker would trip.

All wire is rated for a specific amount of ampacity based on the type of insulation on the wire, how the wire is installed (ie. in conduit, free air, etc), and by the type of material the wire is made of (ie. copper, aluminum).

Power is produced by voltage and current....and power is dissapated in the form of heat. Increase the current and increase the power.


--
This information has been edited and reviewed for errors by your favorite resident sparky.

Originally Posted By: Dennis Bozek
This post was automatically imported from our archived forum.



I must have been asleep when I wrote this…and here it is the way it should read lol…


In a commercial environment, where lighting can at times be run 24/7, most contractors here will design the build so that no single breaker will be drawing more than 35% of the given rating of the breaker at any time over 3 hours of use. This keeps the breakers somewhat cool. If the circuit was designed for 80% on a continuous load, that panel and those breakers would be very hot, but typically would not trip. If the breaker had loose connections on it, such as in a double tap, the breaker does get warm but it does NOT trip because of the HEAT. It trips because of the current produced by the loose connection. Again, as a circuit tries to deliver power, if the connections are loose, arcing will happen. As the wires arc to make contact to the breaker they are connected to, carbon builds up on the loose connection thus making it harder to make contact. The carbon then causes more resistance thus increasing the current. When the breaker reaches the point that it is saturated with the amount of current draw expected of it, THE BREAKER WILL TRIP.


--
This information has been edited and reviewed for errors by your favorite resident sparky.

Originally Posted By: Dennis Bozek
This post was automatically imported from our archived forum.



Jeff…


Yes the preferred installation in this case would be to splice the wires outside of the electrical panel and then feed them into the panel. If there were a lot of wires to splice, one might put a trough above the panel and then do the splicing in the trough, and feed the new wires into the panel trough conduit or flex.


--
This information has been edited and reviewed for errors by your favorite resident sparky.

Originally Posted By: jremas
This post was automatically imported from our archived forum.



Dennis, Thanks for the informational reply. Looks like we are on the same page.


Hey Joe F, what the he8% are you talking about the heat vs the amperage? One in the same, no heat without amperage, no amperage without heat. It is the combo of E-I-R that makes electricity work. I must be confused with your previous reply because you normally make alot of sense.
Thanks


--


Jeff Remas
REMAS Inspections, Inc.
Northeastern PA & the Poconos
www.NEPAinspector.com

570-362-1598

Originally Posted By: jfarsetta
This post was automatically imported from our archived forum.



the current draw. The poor connection causes a momemtary surge in amp flow, due to the fluctuctions in resistance. The resultant arcing produces heat, along with the increased flow of electrons through the breaker, creating friction and resultant heat within the breaker, itself.


So, the increase in resistance caused by the carbon you describe would actually decrease the current draw, according to Ohm's law. In the case of an arcing circuit, something else is causing the breaker to trip.


Originally Posted By: Dennis Bozek
This post was automatically imported from our archived forum.



That is true Joe because current and resistance are indirectly proportional to one another. Nevertheless, in this situation, because the connection is loose, it is working harder to make contact and this increases the amount of current at that point. Voltage times current will give you power, whereas voltage and current are directionally proportional to power. Increase the current and the power increases. The connection then becomes quite warm which eventually causes the insulation and/or breaker to melt. As the connection becomes worse and worse due to the arcing going on, the current becomes substantially higher until eventually the breaker trips. This problem commonly is caused by a loose connection, whether it be a double tap or just a loose screw on the breaker. In commercial environments, it is commonly seen in bolt on breakers, whereas the connection point to the buss is loose.


A good way to look at this would be to compare it to that of a water hose. If water is flowing normally and suddenly the line becomes blocked, the pressure(current) of the water would increase because the line has become smaller due to the blockage(resistance). If the hose is only rated for so much pressure (current), it will eventually burst if that is exceeded past the point of the rating (the breaker trips because it's ampacity rating has been exceeded). So in the case above as the resistance of that circuit increases so does the current. The current increases more and more as the arcing continues due to the loose connection (as the blockage in the hose becomes bigger it creates the pressure in the water to increase).

In Hvac for instance, duct work is smaller at the end of the run versus the beginning of the run. This is because you want the air flow to increase so that it can be felt at the end of the run. They increase the pressure of the air flow by decreasing the size of the duct. Air flow increases for there is more resistance due to the smaller duct. So although ohms law says that the current will decrease as the resistance increases, that does not hold true in this instance.


--
This information has been edited and reviewed for errors by your favorite resident sparky.

Originally Posted By: jmyers
This post was automatically imported from our archived forum.



Dennis,


I was not disagreeing with you just curious to your reason(s) why you do not like double taps.

When it comes to calling double taps, I really don't follow any rhyme or reason. I will try to explain what I call when I see it.

When the breakers are rated for double taps and there is space left in the panel, I like to see one wire per breaker.

When the breakers are rated for double taps and there is no space left in the panel, I suggest they have them checked by a professional electrician to ensure they are safe. I mean, no overheating, no insulation melting, not overloaded, sized correctly etc.....

When the breakers are not rated for double taps I call them out. Further evaluation by an electrician and corrections based on their findings. When the sellers electrician states there is noting wrong with that panel....I ask him to put it in writing....I did! ![icon_biggrin.gif](upload://iKNGSw3qcRIEmXySa8gItY6Gczg.gif)

You would be absolutely surprised how fast things get fixed when you ask them to put it in writing that "nothing is wrong". Works every time.

Joe Myers


Originally Posted By: jmyers
This post was automatically imported from our archived forum.



BTW…you people are getting a bit technical for lowly home inspectors, aren’t you?


Joe Myers


Originally Posted By: Dennis Bozek
This post was automatically imported from our archived forum.



Lowly???



This information has been edited and reviewed for errors by your favorite resident sparky.

Originally Posted By: jmyers
This post was automatically imported from our archived forum.



Yes, lowly. icon_biggrin.gif


Joe Myers


Originally Posted By: rking
This post was automatically imported from our archived forum.



Joe F.,


Ditto…


But in the Ontario Electrical Safety Code it quite plainly states “Each circuit breaker or fuse may supply only one circuit. It is not correct to connect two or more wires to a circuit breaker or fuse.”


But on the other hand it is an accepted practice to 'pigtail' two circuit wires together in a panel and have only one wire directly connected to the breaker bus.
Go figure!


--
Muskoka Home Inspections
"Wisdom is the Anticipation of the Consequences"
Steering Committee Member At Large

Originally Posted By: Dennis Bozek
This post was automatically imported from our archived forum.



icon_surprised.gif Well Bob I don’t know a thing about the Canadian codes but I would hope they would be close to what we follow if not the same. Regardless, that is a funny one…basically doing the same thing as double tapping…and actually making it worse cuz a wire nut will burn faster than a breaker would lol. They give off a distinctive smell too!



This information has been edited and reviewed for errors by your favorite resident sparky.

Originally Posted By: Dennis Bozek
This post was automatically imported from our archived forum.



icon_rolleyes.gif Well Joe I surely do not think HI’s are lowly…not even in Russ’s case. (Sorry Russ ya know I had to say that lol ) Believe me there is a ton of stuff I don’t have a clue about but that doesn’t make me lowly to someone who does. I have to admit as much as I hate to that Russ is fairly well informed about this HI stuff and even though him and I do not agree on most electrical posts…I value his opinion and I don’t feel lowly to him either.



This information has been edited and reviewed for errors by your favorite resident sparky.

Originally Posted By: jmcginnis
This post was automatically imported from our archived forum.



This is getting too technical but I just have to add my 2 cents here… I have to disagree, Dennis… even in this case the laws of physics are not changed… whenever resistance goes up… current goes down…as long as voltage stays constant…the reason there is a heat build up is because an electrical arc is around 40,000 degrees F… now granted, since it’s a very small arc it doesn’t melt everything right away but given enough time it will eventually burn off the connection or destroy the breaker…in your analogy with water… water pressure is actually comparable to Voltage in a circuit and not current… voltage is electrical pressure… current would more correctly be compared to the actual water…what would happen if you turned off the breaker? The arcing would stop… that’s because a breaker in the “open” position offers virtually infinite resistance and stops current flow completely… so when resistance increases current decreases… just thought it was worth explaining …