Originally Posted By: Dennis Bozek This post was automatically imported from our archived forum.
If you have a current clamp JM, the next time you come across a double tap that is “arcing”, place the clamp on the wire and measure the current at that given time. I know…I know…sounds strange but if you have a chance…try it. I have physically done this on circuits like we are chatting about. The current is higher than under normal conditions due to the faulty connection…and high enough to trip the breaker.
Voltage is a potential where current is the force of that potential, the force that moves. You can have 10,000 volts and still only have a milliamp of current depending on the load of the circuit (resistance). Decrease the resistance and yes the current increases, but not the voltage. The current therefore is the water and air flow in my example. As the hose became blocked or the duct became smaller the water flow and air flow became greater. In actuality, the resistance became less for the size of the hose decreased as well as the size of the duct. Therefore the resistance is the blockage and size of the duct. The voltage cannot increase in a home. It is 220 volts or 120 volts period. The only thing that can increase is the load or current. The key word here is "flow" otherwise known as current. If the water tank held 50 gallons of water, it would not matter what you did to the water line connected to it.....the water tank would still hold 50 gallons..therefore the water tank is the voltage.
Your right this is getting far too technical even for me....
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Originally Posted By: Dennis Bozek This post was automatically imported from our archived forum.
120 volts…still kicking…I get that stuff all the time…it’s like nothing to me…just keeps me awake…sometimes I wonder if I am like that ole tv repairman…if he doesn’t get his shock once a day he cannot function…actually though I rarely get shocked…
240 volts....only had that once...didn't much care for it...luckily there was very little current behind it and what was there was alternating....kicked me right off....
480 volts....makes ya taste copper for sure....got 277 once or twice....which is a product of 480....lemme tell ya it was no fun....eyes get blurry....knees get weak....makes ya feel like you been lifting weights...then the nausea sets in....not good at all....
4160...a common commercial voltage....mean stuff....never touched it...don't really want to.....
-56,000 volts dc.....yep I got it....I felt like i was on a hollow wooden box and I jumped 10 feet in the air and landed square on the box....I was lightheaded, nauseated, and quite goofy for several hours. This voltage was on the plate of a magnetron for a high power radar I worked on while in the Marines....long story how I came to meet this votage and needless to say...we didn't become friends.
Was pure potential....the basically discharged through my body....fortunately it was not constant otherwise....I would have never been able to talk to all you wonderful people...oh you too Russ. 
Did you know you could hold a bare wire with 120 volts on it and not get shocked? It's true....if anyone wants to know how....you are crazier than I am....but I have a way....
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Originally Posted By: Dennis Bozek This post was automatically imported from our archived forum.
Well Dave us sparkies are a bit shocking at times
We think it is cool to watch something fry or melt....
But on to your question....The electrical panel (EP) has two lines (legs) of ac voltage coming into it. Each stab on the buss is a different phase than the other....or phase A and phase B. Typically phase A is black then phase B is red. In a 3 phase panel there would also be a Phase C and it would be Blue.
Now first of all you should not double lug at all...and yea I know all the arguements about breakers rated for double taps, etc. Frankly it doesn't matter what color you put on the breaker unless of course it is white, gray or green. Make those colors hot and there will be a few electricians looking for you.
I really cannot give you a good answer on this one because first I do not double tap a breaker unless such has to be done for emergency purposes. Secondly, if you tie phase A to phase B...let me know before you do it....I want to put my armor on. Lastly, Red, Black, Blue, Yellow, Orange, Brown, Pink, and any color other than White, Gray and Green are always and forever hot....so if you really want to be creative here....I'd go for black and yeller....or maybe a nice contrast of blue and red....with a white one too...be a little patriotic lol.
Bottom line Dave without all the humor....my answer is NO. Don't double lug. Save the Black wire for phase A and the red wire for phase B as you would see in a Edison.....now it's time for my daily dose of positrons....goodnight.
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Originally Posted By: jmyers This post was automatically imported from our archived forum.
Dennis,
You did not get shocked because you touched the 120 volt wire, you were shocked because you were grounded to the earth. How servere you were shocked depends on how well you were grounded.
For instance, linesman that work on the high tension wires (up to 750,000 volts) work on those voltages bare handed by charging their bodies to the same voltage of the wire. They are not shocked by charging themselves to the same voltage because voltage takes the easiest path to earth. If their body were to become grounded to earth, they are extra crispy within seconds.
Let me assure you that had you been better grounded to earth on the 277 or the 480 you would be dead. Those voltages tend to fry you alive from the inside out, know what I mean! 
Originally Posted By: dvalley This post was automatically imported from our archived forum.
Dennis,
See...I told you something was wrong with you.
When I asked the question of red & black wires into the same breaker, it was a joke. I was trying to be funny but you took me seriously.
Stop touching those 277's and lets have a copper tasting contest.
I'm happy to have an electrician (such as yourself) on this board. I will have future questions concerning Homeowner Upgrade electrical issues and you will gladly be my mentor.
Originally Posted By: Dennis Bozek This post was automatically imported from our archived forum.
Dave,
I kinda thought it was a joke, but then I wasn't sure lol. So I treated it like a real question lol. I'd be glad to answer any of your questions to the best of my knowledge and expertise. If I don't know a certain topic I won't bs' you. Electricity is far too dangerous to give someone the wrong info.
Dennis
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Originally Posted By: roconnor This post was automatically imported from our archived forum.
Dennis … do you mean that a loose/degraded connection will actually decrease resistance since there is less wire contact/area, and thus increase current since I=V/R. [nah … check that … see below]
Note that the special breakers listed for two wires (e.g. SQ-D Type-QO) technically do not have a "double tap". If you look closely at these breakers, they have a special pressure plate with individual slots/groves on either side of the screw for the wires. This is not a violation of NEC-02 110.3(B) or 110.14(A) which requires one wire per terminal unless otherwise listed for that, since there are actually two terminals/slots. But 2 wires on a standard breaker would be a "double tap" and a violation of the code. And, a double tap of neutral wires on a neutral buss lug is a violation of NEC-02 408.21, but multiple ground wires/taps at the ground buss is permitted as it is usually listed for that.
Just so you know, NEC-02 312.8 specifically ALLOWS splices (wire nuts, etc) in a service panel cabinet as long as the 75% (gutter) fill limit isn't exceeded. Even though panel splices are permitted, most electricians/inspectors seem to consider this poor practice and the fill limit can be exceeded with a packed panel ("birds nest") that has splices.
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: jmcginnis This post was automatically imported from our archived forum.
Robert… thanks for posting those code sections… but I have to question your conclusion about less wire contact equals lower resistance… less wire contact or using smaller wire will increase resistance… for that reason the larger the wire diameter the more current it can carry…I think Dennis drew his conclusions about the resistance in an arcing circuit from reading his clamp-on ammeter during the arcing… the meter needle probably jumped around alot and spiked above the breaker rating at times… but in my opinion this would be due to the arcing and the load being connected and disconnected rapidly because of the arcing… if the load consisted of tungsten filament bulbs as in incandescent lighting or in some kind of motor loads then the needle would spike alot and quite often and it would be possible to interpet this as a result of lower resistance at the connection point…in reality the resistance at the connection point actually increases but the resistance at the load … if it is partly a motor load or incandescent lighting, would be lower at start up and then increase quickly…with an arcing situation this would happen many times per second causing the needle of the clamp-on ammeter to jump and spike…what do you think?
Originally Posted By: roconnor This post was automatically imported from our archived forum.
Jack … Actually on second thought you are right about the wire resistance increasing as the wire gets smaller, and there is another reason for the current spike … brain fart …
– Robert O’Connor, PE
Eagle Engineering ?
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I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: Dennis Bozek This post was automatically imported from our archived forum.
Well gee…I know you can splice in a panel…I just don’t do it and many inspectors frown on it. It is far better to make your splices outside of the panel say in a junction box or a gutter. The more splices there are in a panel, the harder it becomes to work on it or troubleshoot any problems. Nevertheless, splices are allowed…just not a good thing to do in my opinion.
I install SQD panels more often than any other brand of panel purely because they are quality panels. I know all about the QO breakers and until the NEC changes the rule about double taps...I will not do them nor will I allow them. A dbl tap on a single branch circuit isn't as bad as a dbl tap or even triple tap on the main feeders. This type of dbl tap is what I commonly run across and it is typically always the air conditioner. What freaks me out is how a HVAC guy landed that wire beneath the main feeders!! 
Although most of those types of dbl taps are usually fed to another breaker box someplace or a disconnect, I believe that it is the most dangerous dbl tap to have in a panel due to the kind of amperage fed across those mains. I have seen main breakers melt purely due to a loose dbl tap. As that connection arcs, it gets hotter and hotter. Current also increases across it because of the arcing. Most of the time a dbl tap will cause the breaker to trip not because of the heat but because of the current.
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Originally Posted By: Dennis Bozek This post was automatically imported from our archived forum.
Well Dave, if they do the dbl tapping on the load side of the breaker, which they commonly do not do, all they would have to do is shut the breaker off. Usually though, the dbl taps are on the line side of the breaker or right at the main lugs!!!
I agree that is exceptionally dangerous to do at that point. It might be that they are loosening up the connection and then sliding the wire into the lug and retightening the connection. I remember one time, I got this emergency call. It was a house that had the main breaker smoldering from a dbl tap that had been placed on it obviously by a hvac guy. Even after I had turned the main breaker OFF, the breaker continued to arc and smoke and smell really bad. I then pulled the disconnect for the air conditioner, as there was no breaker feeding it. To no avail, the main breaker continued to arc. I finally pulled the meter which finally stopped the meltdown. I then pulled the main breaker and replaced it with another. I had to cut the wires from the meter that were in the main breaker because they had more or less welded themselves in the main. Then I had to refeed the line side of the meter base because by the time I had cut off all of the melted and welded wires going into the main, the feeders were too short. After replacing the main breaker, I pulled a 40 amp 2 pole breaker from my truck stock and then hooked the air conditioning wires into it. The wires which were dbl tapped off of the line side of the main were lose, thus causing arcing, overheating and a increase in current. Eventually the main breaker said ENOUGH and promptly started to meltdown. What got me, was that there was two spaces available in the panel to hook up the a/c. Why someone would dbl tap the mains versus putting in a breaker is beyond me!!! Seems the a/c had only recently been installed like 6 months ago. I handed the customer a $600 bill and told him to send it to the HVAC company that installed the a/c. Whether he did that or not, I do not know. Either way, the NEC specifies that dbl tapping is prohibited and this is an excellent reason why. I don't care if some breakers are rated for dbl taps or not. It is a bad practice to do especially if one is dealing with different wire sizes at the breaker to be dbl tapped!
Anytime I see a dbl tap off of the mains I alert the customer to it and explain to them why it is a bad thing to do. I've even seen the worse where triple taps took place off of the main. With nothing in between the main and the a/c disconnect in the above case, the 8 gauge wire used to power the a/c was basically not protected in any way. It left the panel in a piece of sealtight and then traveled about 20 feet to the a/c disconnect. Fortunately, the a/c disonnect would have more than likely blown a fuse or two in the case of a a/c problem. But can you imagine what would have happened if for whatever reason the fuses don't open? 
Double taps and double lugs is a touchy subject with me. If the NEC ever allows such to happen, I will still not do it! The only time I would ever consider dbl taapping any breaker is in the case of an extreme emergency. If I had to do such, I would verify the current on the breaker that the dbl tap would be placed. I would also inform whomever that the removal of the dbl tap requires immediate action.
Those that think dbl lugging neutrals is not a problem are also in for a surprise. It is as dangerous as dbl tapping a breaker for the neutral or return wires are current carrying conductors. The only sbl lugging allowed in a panel would be the ground wires and then both wires dbl lugged must be ground wires. Whew I got a bit long winded on this one
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Originally Posted By: Dennis Bozek This post was automatically imported from our archived forum.
Correction!
The statement I made...."Then I had to refeed the LINE side of the meter base because by the time I had cut off all of the melted and welded wires going into the main, the feeders were too short. " Should actually read "Then I had to refeed the LOAD side of the meter base because by the time I had cut off all of the melted and welded wires going into the main, the feeders were too short. "
-- This information has been edited and reviewed for errors by your favorite resident sparky.
Originally Posted By: roconnor This post was automatically imported from our archived forum.
Dennis … About the QO style gang breakers, have you checked the way the latest 2002 NEC reads on this, as Section 110.14(A) allows more than one conductor per terminal if it is listed for that purpose … which the QO style breakers are.
I know some sparkies dont like the gang breakers or panel splices, but from an HI point of view I think these items alone are just something to note and shouldn't be flagged. You could get egg on your face since they are allowed. But if you see a packed panel with a bunch of gang breakers, it is an indication that the panel may be undersized.
But a double lug on the main or neutral buss, or a double tap on a standard breaker, should be flagged ... a clear code violation and safety issue.
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: Dennis Bozek This post was automatically imported from our archived forum.
Robert,
Yes I know all about that article  but I still won't allow them. Anyway my biggest concern is the dbl taps on the main lugs and neutral lugs. As far as the breaker issue....and dbl taps go...I reckon I'm just being safer than most even though the nec permits it....I've seen too many panels with toast connections due to dbl taps.
-- This information has been edited and reviewed for errors by your favorite resident sparky.
Originally Posted By: roconnor This post was automatically imported from our archived forum.
Okay … agreed that double lugs on the main or neutral buss are the big red flag safety items. I would flag a double tap on a std breaker also, but not flag a QO type gang breaker with 2 wires unless it was a packed panel with a bunch of them (indication of overloaded service).
I understand your position as an electrician, but as an HI ya don't want to flag something and then have an electrician or local electrical inspector say "why did the HI flag that ... it's perfectly fine" and end up with egg on your face.
Have you seen problems with these QO breakers I am not aware of, or do ya mean that a packed panel with a bunch of these gang breakers generally indicates a possible overloaded service that should be checked out.
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
