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Old 06-03-2008, 06:30 PM   #16
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Max amps allowed - electrician advice needed


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Originally Posted by Speedy Petey View Post
Seriously? This is absolutely typical in the US. Many older main panels had only one bar.
Newer stuff has two bars that are bonded.

The house is about 16 years and the panel has only one bar as described.
Grounds are just lined up on the top set screws with neutrals on the bottom set screws.

Actually the holes and the set screws are pretty large. They arent tiny set screws. But I assume that handy petes explanation still applies to this panel eventhough it only has one bar for both return and ground?

And about my one question ... I can safely double up on a ground to free up a spot for another neutral then?

Thanks handypete and speedy petey.
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Old 06-03-2008, 07:48 PM   #17
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Max amps allowed - electrician advice needed


Yes. You can double a ground to make room for the netural.
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Old 06-03-2008, 08:31 PM   #18
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Yes. You can double a ground to make room for the netural.
Thanks jbfan.

I took a look behind the panel and see that this is exactly how it was done. There are about half as many spaces used for ground as there are for neutral. So they obviously doubled up on the grounds when the wired the breaker box.

I have added a couple circuits in the past and used a seperate spot for each ground. I see that there are a few singles on 110 circuits that I can double up on. It even says in the box that you can wire up to two 12's or three 14's together in one space. Just says that they need to all be the same guage wire.

I appreciate the advice, thanks for everyones input.
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Old 06-03-2008, 08:33 PM   #19
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Max amps allowed - electrician advice needed


As Chris pointed out, this circuit is not subject to the continuous duty restrictions. As long as your circuit breaker isn't tripping, you are fine as it is.
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Old 06-04-2008, 05:37 AM   #20
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Max amps allowed - electrician advice needed


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Originally Posted by HandyPete View Post
Dude,

The neutral is a current carrying conductor and will heat-up when there's current flow so the conductor needs to be connected all by itself to the bar. Imagine the tiny point of contact between the wire and bar, when you have two wires the amount of heat is doubled and is not allowed. On the other hand, the ground wire doesn't have current flowing through it. The ground wire is a return path only when there's a fault to ground, so when that happens the breaker will trip really fast and no heat will accumulate due to current flow.

- pete

I'm kinda dumbfounded, There's not two separate bars in the panel? I've never seen neutral sand grounds all tied to the same bus. hmmm?
It is more so that you don't inedvertantly disconnect a neutral for a live circuit.

Example: Circuits 1 and 2 have the neutrals doubled up in the bar. The circuit 1 is being removed. So he flips the breaker, and disconnects the hot lead, ground and finally the neutral. While in the process of pulling the cable out fromt the box, the neutral from circuit 2 is forgotten and is still not hooked up. Now you have an open neutral for that circuit. VERY bad situation.
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Old 06-04-2008, 08:58 AM   #21
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Originally Posted by CowboyAndy View Post
It is more so that you don't inedvertantly disconnect a neutral for a live circuit.

Example: Circuits 1 and 2 have the neutrals doubled up in the bar. The circuit 1 is being removed. So he flips the breaker, and disconnects the hot lead, ground and finally the neutral. While in the process of pulling the cable out fromt the box, the neutral from circuit 2 is forgotten and is still not hooked up. Now you have an open neutral for that circuit. VERY bad situation.
So it would be more of a code/safety thing rather than an actual fire or electrical hazard while it is actually hooked up?
That makes sense, I know alot of code doesnt involve actual hazard but is more to prevent a bad situation or protect the individual or next electrician to come work on the wiring.

I was thinking of the heat explanation. I was thinking that the heat from the neutral on a single 20 amp circuit with, say 14 amps running on it, would be worse than the heat on two neutrals tied together from two 15 amp circuits with maybe 6 or 7 total amps between them. So the heat thing could makes sense depending on the situation but without a fault somehwere I dont see how there could be enough heat to cause a problem by putting two neutrals under one set screw. The set screws are pretty big. You have to hold the wire in place to keep it centered.

Again, im not doubting that it could be part of the reason but CowboyAndy's explanation makes more sense I think.
Either way, advice heeded and thank you for the help.

There is another issue I noticed in the box.
There are 3 main wires, large, coming in from the meter. The two phases to the main breaker and the one ground that attaches to that same ground/neutral buss bar with a large Lug/clamp that attaches to bar at one of the threaded set screw holes. That is fine but ...

Then there is another ground, or actually a bond that runs with a large, stranded bare wire from the metal conduit where the main supply wires enter the breaker box to the same neutral/ground bar. This attaches with a sorta split nut type clamp that is screwed onto the metal conduit where it enters the breaker box through the wall but then the other end is just shoved into one of the holes made for the circuit grounds and neutrals. You can tell it is very tight fit but it does fit in there.
The thing is that There is a larger lug that is just sitting on the bottom of the box and the set screw looks stripped out. So what it looks like the original electrician who installed the box did was he had a stripped lug/clamp that was supposed to be used to attach that large bond wire to the neutral/ground bar but since it was not usable he just got it to fit directly in one of the smaller holes and just dropped the bad lug/clamp on the bottom of the box.

It has been this way for a long time obviously. But how much of a bad thing is this? Can I just leave it or should I get the lug and correct this? I assume that this bond is just in case the box and conduit gets energized due to some fault like a break in the supply wires insulation or something.
Should I just leave it or should it be dealt with?

Thanks. I know this has turned into more than one question and I appreciate all the advice.
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Old 06-04-2008, 07:14 PM   #22
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Max amps allowed - electrician advice needed


So far, so good, lot's of good talk.

Somewhere I heard that two wires under one set-screw is a no-no because of "thermal cycling" The expansion-contraction of all the parts including two wires just isn't the best condition.

-pete
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Old 06-05-2008, 12:24 AM   #23
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Max amps allowed - electrician advice needed


There is no electrical hazard having two neutrals under a screw...provided they would be of the same awg. Same for equipment grounds. the opening of a neutral or more appropriately grounded leg of a 120 volt branch circuit poses no danger outside of the obvious fact nothing will work on the branch circuit with the open in the neutral.

The reason for 408.31 to require the termination of grounded conductors to one terminal is to prevent the inadvertent opening of a multiwire shared neutral during a maintenance event in the panel. This will allow high voltage to appear on the branch circuit that may damage equipment.

Last edited by Stubbie; 06-05-2008 at 12:28 AM.
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Old 06-05-2008, 08:57 AM   #24
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There is no electrical hazard having two neutrals under a screw...provided they would be of the same awg. Same for equipment grounds. the opening of a neutral or more appropriately grounded leg of a 120 volt branch circuit poses no danger outside of the obvious fact nothing will work on the branch circuit with the open in the neutral.

The reason for 408.31 to require the termination of grounded conductors to one terminal is to prevent the inadvertent opening of a multiwire shared neutral during a maintenance event in the panel. This will allow high voltage to appear on the branch circuit that may damage equipment.

Thank you fpr your input Stubbie.

If I understand you, you are saying that code requires only one neutral OR one ground under any one screw. Correct?
In the box itself there is a sticker that states that up to 3 #14 grounds can be placed under the same screw as long as they are the same guage.

So has code changed to not allow this or is it still ok for grounds, just not the neutrals? My panel has several set screws with 2 or 3 circuits grounds twisted together under one screw. There would be no way to correct this, not enough seperate connection holes on the bar.

Thanks
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Old 06-05-2008, 10:53 AM   #25
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Max amps allowed - electrician advice needed


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Originally Posted by Des View Post
Thank you fpr your input Stubbie.

If I understand you, you are saying that code requires only one neutral OR one ground under any one screw. Correct?
In the box itself there is a sticker that states that up to 3 #14 grounds can be placed under the same screw as long as they are the same guage.

So has code changed to not allow this or is it still ok for grounds, just not the neutrals? My panel has several set screws with 2 or 3 circuits grounds twisted together under one screw. There would be no way to correct this, not enough seperate connection holes on the bar.

Thanks
You are probably confusing the word "grounded" with "groundING". The white neutral is grounded, the green or bare "ground" is the equiptment grounding conductor.


You CAN put more than one groundING (bare/green) conductors under one screw IF the panel is rated for it.

You CANNOT put more than one groundED conductors under one screw.
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Old 06-05-2008, 11:28 AM   #26
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Max amps allowed - electrician advice needed


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You are probably confusing the word "grounded" with "groundING". The white neutral is grounded, the green or bare "ground" is the equiptment grounding conductor.


You CAN put more than one groundING (bare/green) conductors under one screw IF the panel is rated for it.

You CANNOT put more than one groundED conductors under one screw.
Maybe ... thats why I call the " grounded" = Neutral and the "Grounding" = ground instead of grounED and groundING


Anyway, that is the way I thought I understood it before Stubbies post.

Bare (grounding) can be together under one screw as long as they are the same size conductors and I dont exceed the limit ...

White (neutral, return, grounded) has to be under its own screw.

Thanks again.
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Old 06-05-2008, 09:11 PM   #27
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Max amps allowed - electrician advice needed


Hello Des

I was simply making clarification as to the requirement of one neutral under one terminal provided by 408.31. The other reasons though interesting to consider have no bearing on this requirement. I was also making clarification to there NOT being a very bad situation if a grounded leg (neutral) on a 120 volt branch circuit opened. There is no threat to human safety if two neutrals are under one screw and one becomes opened. There is however a threat to property/equipment damage if that opened neutral is a shared neutral on a multiwire circuit operating line to neutral loads for 120 volt equipment.. (the reason for 408.31).

Your equipment 'grounding' conductors are as you have said...you can put as many of the same awg under one screw as the manufacturer allows.

It is also important to get terminology correct. In a typical 120 volt branch circuit there is no neutral wire only a grounded leg usually white. It is common for us to refer to the white of a 120 volt branch circuit as the neutral, but it is not a neutral.
A neutral serves 2 or more ungrounded conductors and carries the unbalanced current between those conductors. A 120 volt multiwire shared neutral, a range circuit, a dryer circuit, a dwellings utility service are examples of wiring that include a neutral...ie...2 hot conductors, and a neutral there may or may not be an equipment grounding conductor.
the NEC has been very confusing in calling the EGC a grounding conductor as it is not that at all but more appropriately it is a bonding conductor.
A grounding conductor connects equipment to earth (ground) to limit voltage on equipment due to lightning strikes and power surges etc..very high voltage events.
Examples of a "grounding" conductor would be your Grounding electrode conductors (GEC's) which connect your service equipment to earth at the electrodes such as metal water pipes and ground rods. Unfortunately the equipment "grounding" conductor is a bit misleading and the NEC has yet to correct the misnomer in the term. The bare/green wire is not a grounding conductor but is used as a bonding means to connect metal that is likely to become energized in the event of a fault to the 'effective fault current path' back to the source which is the center tap of the utility transformer.

As for the normal operation of your electrical system 'grounding' is not needed to provide for its operating correctly or for safety.

The term "grounded" is best used to describe a system or when refering to the service neutral when bonding metal to provide the effective fault current path to facilitate the opening of a protective device like a circuit breaker.

Ground is the USA's electrical term for earth.... everywhere else on the planet they simply call it..... earth.

You will see misnomers of these terms quite often and confusion is very common even in the language of the NEC prior to 2002.
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Old 06-05-2008, 10:31 PM   #28
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Hi Stubbie

I got it.

Obviously I am just referring to things in laymens terms and
the electricians here understand what I am saying, or trying to say.
So I think that eventhough the terms are not completely accurate I am understood and that is what is most important.

But that said, I very much appreciate the education in the proper terms.
I cant promise that I will remember them seeing how I dont deal with this on a daily basis by any stretch. But I do appreciate the information and will try.

Thanks again everyone for the help.
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