Neutral and Earth Ground Question

They can remain connect to EACH OTHER but not connecto to neutral/ground.

Maybe.

I not going to get into this one much further, but, Someone (With Pure Genius) already clearly Stated the Science behind the issue of Neutral & Bonding Ground with a down vs upstream explanation., it is very dangerous to create 2 neutral paths in a system (leaving users exposed to objectionable current within said system) and that is why there are Specific Occasions when you Shunt them Together an Specific Conditions in which you Do Not. [if you understand this Concept you do not need the NEC guidelines to make a safe system] =AEoy

408.21 Grounded Conductor Terminations. Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor.

Tom; You're like the devil quoting bible verses };- That means one conductor per terminal, & only of equal system coverage per buss, right ? all hell breaks loose when you criscross neutrals & grounds in a fully bonded seperate neutral panel. =AEoy

Don't start with me :-) I'm certified

|> |> 3. Neutral sharing with ground ... could be the same circuit. |> | |> | That has potential problems in that the "ground" and "neutral" of a | circuit |> | may easily remain connected while both are connected from the |> | "ground/neutral." IF the corresponding HOT wire remains connected, you | can |> | easily have a section of "ground" that's actually HOT. |>

|> Huh? You're saying that a problem can exist because ground and neutral |> would remain connected while a hot wire remains connected? | | They can remain connect to EACH OTHER but not connecto to neutral/ground.

If you disconnect the neutral from the bus on a DEAD circuit (because you properly switched off the breaker that the hot wire(s) is/are connected to first, how is this a hazard?

Of course there is a hazard if the circuit is not dead. If you are saying that the code provision intends to protect people from disconnecting wires on LIVE circuits, then why is it not requiring that neutral and ground wires be WELDED to the bus to prevent this?

I suggest killing the circuit you intend to work on, and the whole whole panel. If the neutral and ground wires sharing the same hole, for the same circuit, are stuck together, I think you will see this, and would be well advised to not turn the power to that circut back on until the problem is corrected.

It makes sense to not mix the circuits (except for ground to ground mix).

| I not going to get into this one much further, but, Someone (With Pure | Genius) already clearly Stated the Science behind the issue of Neutral & | Bonding Ground with a down vs upstream explanation., it is very | dangerous to create 2 neutral paths in a system (leaving users exposed | to objectionable current within said system) and that is why there are | Specific Occasions when you Shunt them Together an Specific Conditions | in which you Do Not. [if you understand this Concept you do not need the | NEC guidelines to make a safe system] ?oy

Roy, you need to get back on your meds. You're mixing threads, again.

On Wed, 01 Jun 2005 04:05:25 GMT HorneTD wrote: | ehsjr wrote: |> HorneTD wrote: |> |>>>

|>>

|>> The US National Electric Code specifically forbids a neutral being |>> terminated with another conductor in the same termination within a |>> panel. That rules out sharing a terminal with the Equipment Grounding |>> (Bonding) Conductor. |> |> |> What article? |> Ed | | 408.21 Grounded Conductor Terminations. | Each grounded conductor shall terminate within the panelboard in an | individual terminal that is not also used for another conductor.

IMHO, this rule is technically overreaching. It would not be overreaching if the rule qualified "another conductor" as "another conductor which is part of another circuit or system".

OTOH, if I were writing the rules, I'd make it overreach even further by requiring the same of the Equipment Grounding Conductors as well, including separate bus bars.

Just to make this clear, I am differentiating between what is electrically safe and what is procedurally safe. Having neutral and ground in the same hole, or even mixing circuits in the same hole, is safe as it stands. But procedurally, we do know that people will screw up, and the code intends to help prevent them from earning a Darwin award. I have no problem with most instances of procedurally safe being part of the code. But I will dispute it when someone claims something is electrically unsafe when in fact it is safe, even though I would personally practice the procedurally safe methods, myself.

Insulation color is probably the most significant or well known feature of procedurally safe methods instilled in the code. Electrons are unaffected by the insulation color. If every wire has a yellow colored insulation, but is otherwise connected correctly, it is electrically safe as it stands. But with no color guides, maintenance becomes more difficult, and some will attempt to shortcut that maintenance and end up making things electrically unsafe for others. So we have these procedural rules to protect us from other people's stupidity (and to guide those of us not diligent enough to be sure it is electrically right in the absence of things like wire colors).

Thanks!

Actually, he's more like a guardian angel than a devil. He helped me when I asked him to. :-)

Ed

- That means one

It is the thermal cycling of the current carrying grounded conductor (neutral) that makes having it in the same termination as the Equipment Grounding (bonding) Conductor (EGC) an unsafe practice electrically. There has yet to be devised a terminal that can use one pressure producing part to maintain good electrical contact with two conductors that are thermally cycling at different rates and times. If you look at the breakers that are listed to hold two separate conductors you will see that the conductors are separate from each other and the screw has a pressure washer under its head. The addition of the pressure washer or plate allows solid contact between both conductors and the plate into which the screw is threaded. The pressure washer will flex sufficiently to permit unequal thermal cycling without the connection failing.

In thirty years of electric work I have seen many connection failures caused by improper torquing of connections and by using a single terminal to terminate multiple conductors. The reason that it is safe to use a single terminal to terminate multiple EGCs is that they do not carry current during normal operation and they are not subjected to repeated thermal cycling.

-- Tom Horne

Well we aren't no thin blue heroes and yet we aren't no blackguards to. We're just working men and woman most remarkable like you.

| It is the thermal cycling of the current carrying grounded conductor | (neutral) that makes having it in the same termination as the Equipment | Grounding (bonding) Conductor (EGC) an unsafe practice electrically. | There has yet to be devised a terminal that can use one pressure | producing part to maintain good electrical contact with two conductors | that are thermally cycling at different rates and times. If you look at | the breakers that are listed to hold two separate conductors you will | see that the conductors are separate from each other and the screw has a | pressure washer under its head. The addition of the pressure washer or | plate allows solid contact between both conductors and the plate into | which the screw is threaded. The pressure washer will flex sufficiently | to permit unequal thermal cycling without the connection failing. | | In thirty years of electric work I have seen many connection failures | caused by improper torquing of connections and by using a single | terminal to terminate multiple conductors. The reason that it is safe | to use a single terminal to terminate multiple EGCs is that they do not | carry current during normal operation and they are not subjected to | repeated thermal cycling.

Thank you for a good explanation.

Q: if you needed to connect TWO current carrying conductors to a terminal, and the only choice of lugs available were one with a single hole, and one with 4 holes, and these two conductors would not fit in any one hole on the 4 hole lug, but _would_ fit in TWO HOLES if the strands were split in about equal numbers, would this be electrically safe to put one of the conductors in 2 holes and the other in the other 2 holes?

Oh I know };-) You know what I meant., & Phil Back Off I am going down the line and in due course & On Thread., The World is so full of IF's., But not here., not in this query the Op sent in specifics. Roy From: snipped-for-privacy@bellatlantic.net (ehsjr) Roy Q.T. wrote: Tom; You're like the devil quoting bible verses }; Actually, he's more like a guardian angel than a devil. He helped me when I asked him to. :-) Ed

- That means one conductor per terminal, & only of equal system coverage per buss, right ? all hell breaks loose when you criscross neutrals & grounds in a fully bonded seperate neutral panel. =AEoy Don't start with me :-) I'm certified

I warned you ];-) =AE

From: snipped-for-privacy@mindspring.com (HorneTD) snipped-for-privacy@ipal.net wrote: On Wed, 01 Jun 2005 04:05:25 GMT HorneTD wrote: | ehsjr wrote: HorneTD wrote: The US National Electric Code specifically forbids a neutral being terminated with another conductor in the same termination within a panel. That rules out sharing a terminal with the Equipment Grounding (Bonding) Conductor. What article? Ed | | 408.21 Grounded Conductor Terminations. | Each grounded conductor shall terminate within the panelboard in an | individual terminal that is not also used for another conductor. IMHO, this rule is technically overreaching. It would not be overreaching if the rule qualified "another conductor" as "another conductor which is part of another circuit or system". OTOH, if I were writing the rules, I'd make it overreach even further by requiring the same of the Equipment Grounding Conductors as well, including separate bus bars. Just to make this clear, I am differentiating between what is electrically safe and what is procedurally safe. Having neutral and ground in the same hole, or even mixing circuits in the same hole, is safe as it stands. But procedurally, we do know that people will screw up, and the code intends to help prevent them from earning a Darwin award. I have no problem with most instances of procedurally safe being part of the code. But I will dispute it when someone claims something is electrically unsafe when in fact it is safe, even though I would personally practice the procedurally safe methods, myself. Insulation color is probably the most significant or well known feature of procedurally safe methods instilled in the code. Electrons are unaffected by the insulation color. If every wire has a yellow colored insulation, but is otherwise connected correctly, it is electrically safe as it stands. But with no color guides, maintenance becomes more difficult, and some will attempt to shortcut that maintenance and end up making things electrically unsafe for others. So we have these procedural rules to protect us from other people's stupidity (and to guide those of us not diligent enough to be sure it is electrically right in the absence of things like wire colors). It is the thermal cycling of the current carrying grounded conductor (neutral) that makes having it in the same termination as the Equipment Grounding (bonding) Conductor (EGC) an unsafe practice electrically. There has yet to be devised a terminal that can use one pressure producing part to maintain good electrical contact with two conductors that are thermally cycling at different rates and times. If you look at the breakers that are listed to hold two separate conductors you will see that the conductors are separate from each other and the screw has a pressure washer under its head. The addition of the pressure washer or plate allows solid contact between both conductors and the plate into which the screw is threaded. The pressure washer will flex sufficiently to permit unequal thermal cycling without the connection failing. In thirty years of electric work I have seen many connection failures caused by improper torquing of connections and by using a single terminal to terminate multiple conductors. The reason that it is safe to use a single terminal to terminate multiple EGCs is that they do not carry current during normal operation and they are not subjected to repeated thermal cycling.

Phil on your last Horne TD.,

You can put a Tap Lead on the Single Available Terminal and use some other means to connect the 2 Conductors together with the Tap Lead., and some Experts still swear there is no Magic In Electrical Connections };-)

Roy

You are very likely to fracture one or more of the strands while separating them and the fractures will be back inside the insulation were you will not see it. Buy the proper sized lug for that buss bar and follow the instructions to add it to the bar. If your improvised termination were to fail and cause damage the application of the terminals outside of their listing parameters will be obvious to even a rookie investigator. Your insurance carrier could walk away from your loss. The lug adapter is less than three dollars at a stocking distributer.

On Thu, 02 Jun 2005 16:33:39 GMT HorneTD wrote: | snipped-for-privacy@ipal.net wrote: |> On Wed, 01 Jun 2005 20:04:08 GMT HorneTD wrote: |> |> | It is the thermal cycling of the current carrying grounded conductor |> | (neutral) that makes having it in the same termination as the Equipment |> | Grounding (bonding) Conductor (EGC) an unsafe practice electrically. |> | There has yet to be devised a terminal that can use one pressure |> | producing part to maintain good electrical contact with two conductors |> | that are thermally cycling at different rates and times. If you look at |> | the breakers that are listed to hold two separate conductors you will |> | see that the conductors are separate from each other and the screw has a |> | pressure washer under its head. The addition of the pressure washer or |> | plate allows solid contact between both conductors and the plate into |> | which the screw is threaded. The pressure washer will flex sufficiently |> | to permit unequal thermal cycling without the connection failing. |> | |> | In thirty years of electric work I have seen many connection failures |> | caused by improper torquing of connections and by using a single |> | terminal to terminate multiple conductors. The reason that it is safe |> | to use a single terminal to terminate multiple EGCs is that they do not |> | carry current during normal operation and they are not subjected to |> | repeated thermal cycling. |> |> Thank you for a good explanation. |> |> Q: if you needed to connect TWO current carrying conductors to a terminal, |> and the only choice of lugs available were one with a single hole, and one |> with 4 holes, and these two conductors would not fit in any one hole on |> the 4 hole lug, but _would_ fit in TWO HOLES if the strands were split in |> about equal numbers, would this be electrically safe to put one of the |> conductors in 2 holes and the other in the other 2 holes? |> | | You are very likely to fracture one or more of the strands while | separating them and the fractures will be back inside the insulation | were you will not see it. Buy the proper sized lug for that buss bar | and follow the instructions to add it to the bar. If your improvised | termination were to fail and cause damage the application of the | terminals outside of their listing parameters will be obvious to even a | rookie investigator. Your insurance carrier could walk away from your | loss. The lug adapter is less than three dollars at a stocking | distributer.

This came about from a case where 3 connections need to be made from a single breaker load side. The only lugs available are 1 hole, 2 hole, and 12 hole. With those choices, try making another suggestion.

| This came about from a case where 3 connections need to be made from a | single breaker load side. The only lugs available are 1 hole, 2 hole, | and 12 hole. With those choices, try making another suggestion.

Correction. It is a 6 hole lug. Each of the 6 holes will fit 2/0 AWG. Three 4/0 AWG wires need to be connected. A 4/0 split with 10 strands in one hole and 9 strands in the other should fit based on sizing from NEC tables. That will take 2 holes per wire. Repeat for each of the other 2 wires and all 6 holes are used.

The lug is Square D model PDC6LA20.

If you have a better suggestion, by all means let me know.

Mount a four hole lug of appropriate size on an insulating stand off, bug the three conductors onto a short pigtail off of the breaker using spit bolts or insulating displacing connectors as appropriate, use an insulated multi tap block to join the four conductors to the jumper from the breaker... There is always a code compliant way to do it. You just have to invest the time or the money in hired expertise to find out what that way is.

-- Tom Horne

| Mount a four hole lug of appropriate size on an insulating stand off, | bug the three conductors onto a short pigtail off of the breaker using | spit bolts or insulating displacing connectors as appropriate, use an | insulated multi tap block to join the four conductors to the jumper from | the breaker... There is always a code compliant way to do it. You just | have to invest the time or the money in hired expertise to find out what | that way is.

If I would approve of things like pigtails and splices, I'd just run some

600 kcmil from the main breaker down a raceway and splice off each of the 4/0 feeds into the 3 panels they go to. But my intention is to absolutely avoid splicing (having seen the mess when they fail). I believe the risk is less by just stranding the 4/0 into 2 adjacent holes on the same lug. Or can you show me code that says not to split stranded wire into two holes? I'm not convinced about the "fracturing" issue since this will involve less mechanical stress on the wire than typical wire bending that takes place in typical panels, especially if I use the larger box that would be needed to put all those pigtails below the breaker.