Mechanical damage, or someing else?

[Michael Thomas]

This appears to me to likely just mechanical damage to the outer layer of insulation when when the wires were pulle., covered with a lot of crud,... but the appearance of upper black wire in the last few inches before it enters the breaker leaves me wondering about the possibility of overheating...

Comments?

(Before someone asks about the jumper, yes, it's a load side panel)

[Jerry Peck]

This appears to me to likely just mechanical damage to the outer layer of insulation when when the wires were pulle.,

That's what it looks like, yes. But I would not say "just" mechanical damage in the sense that 'it is just mechanical damage', only in the sense that, yes 'it looks like just mechanical damage and not overheating'.


.... but the appearance of upper black wire in the last few inches before it enters the breaker leaves me wondering about the possibility of overheating...

Hard to tell from the photo, but it looks like mechanical damage.


(Before someone asks about the jumper, yes, it's a load side panel)

Okay, this is 'just a panel', or a 'distribution panel', not part of the service equipment, understand, so ... I am sure you wrote up that green ground being connected to the neutral terminal bar, so no need to comment on it ... ;)

How is that panel secured to the plywood behind it? looks like 3 nails in 3 of the 4 holes, and the upper nail looks like the head is too small to keep from pulling through, which makes me wonder about the use of the same size head nail in the lower holes.

[John Arnold]

...Okay, this is 'just a panel', or a 'distribution panel', not part of the service equipment, understand, so ... I am sure you wrote up that green ground being connected to the neutral terminal bar, so no need to comment on it ...

Confused by your statement, JP. The bond isn't connected to the neutral bar, and that's as it should be, right?

[Jerry Peck]

Okay, this is 'just a panel', or a 'distribution panel', not part of the service equipment, understand, so ... I am sure you wrote up that green ground being connected to the neutral terminal bar, so no need to comment on it ...


Confused by your statement, JP. The bond isn't connected to the neutral bar, and that's as it should be, right?


You are talking about the "bond jumper" on the right (that's GOOD that it is NOT connected), I am talking about the "green ground wire" on the left (that's BAD that IT IS connected).

[John Arnold]

You are talking about the "bond jumper" on the right, I am talking about the "green ground wire" on the left.

I see, said the blind man.

[Michael Thomas]

Jerry's ground wire.

-----------

Yup - nails and drywall screws.

[Ted Menelly]

Nope, looks like that wire heated up to me.

I am sure they would not have just pulled enough wire to just reach the breaker. There is always a little more pulled. If it were damaged at the end it would have been cut off. Like I said. No one pulls just enought to reach the breaker.

Anyway. Just my opinion

[Fred Warner]

If the equipment grounding conductor is intended to be the EMT which is permitted at 250.118(4), then the strap that connects the two bars together (traversing behind the phase busses) should be disconnected in a way that allows the terminal strip on the left to become an equipment grounding bus and the terminal on the right to remain a neutral bus. The manufacturer surely has provided a code-compliant method.

The obvious problem I see is that neutral conductors are connected to the equipment grounding bus (on the left). This is a dangerous condition since it connects the grounded conductor which is a current-carrying conductor to the equipment grounding conductor which is only intended for fault-current. Return current takes every available path back to the source, including the egc. This dividing of the neutral return current could make it possible that during a fault the resistance would prohibit the OCPD from functioning properly.
Neutrals and grounds are not permitted to be connected together on the load side of the service disconnecting means, generally.
The panelboard is improperly connected.

Its a simple fix: Put the bonding strap on the equipment bus and relocate the neutrals to the neutral bus.

[Jerry Peck]

The obvious problem I see is that neutral conductors are connected to the equipment grounding bus (on the left).

Fred,

That "equipment grounding bus (on the left)" is also a "neutral terminal bus" as it is connected to the neutral terminal bus on the right through the metal strap running in that across behind the plate holding the phase conductor bus bars. At least that is the way I've always seen those kinds of interiors and the way it looks to me.

That does not look like one of those 'snap in' terminal bars which simply 'snaps in' to a plastic holder simply to hold it in place.

[Michael Thomas]

A closer look:

[Tony Infelise]

If the equipment grounding conductor is intended to be the EMT which is permitted at 250.118(4), then the strap that connects the two bars together (traversing behind the phase busses) should be disconnected in a way that allows the terminal strip on the left to become an equipment grounding bus and the terminal on the right to remain a neutral bus. The manufacturer surely has provided a code-compliant method.

The obvious problem I see is that neutral conductors are connected to the equipment grounding bus (on the left). This is a dangerous condition since it connects the grounded conductor which is a current-carrying conductor to the equipment grounding conductor which is only intended for fault-current. Return current takes every available path back to the source, including the egc. This dividing of the neutral return current could make it possible that during a fault the resistance would prohibit the OCPD from functioning properly.
Neutrals and grounds are not permitted to be connected together on the load side of the service disconnecting means, generally.
The panelboard is improperly connected.

Its a simple fix: Put the bonding strap on the equipment bus and relocate the neutrals to the neutral bus.

I guess I'm not following you. What I see is a load-side panel (sub-panel) wired with conduit and two floating nuetral bars. There is not an equipment grounding bar. The return current in this panel follows the grounded conductor back to the main panel where the over current protection is located. Re-attaching the bond strap would split the current and cause current to flow over the grounding conductors (the conduit).

[Fred Warner]

As I look at the close up photo provided I see no electrical connection between the "floating" equipment grounding conductor terminal on the left-hand side and the grounded conductor (neutral) terminal on the right-hand side. This is as the manufacturer of this load-center intended.

Now, to make the wiring comply, simply take the bonding strap which is on the right-hand side and move it over to the left-hand side. This will bond the enclosure (which at present is isolated from the equipment grounding conductors). Now if a ground-fault were to occur ( a line-to-enclosure fault) the fault current would travel through the enclosure up the bonding strap, along the EMT (being used as an equipment grounding conductor inplace of and instead of a 4th wire) to the service disconnecting means where it would be directed to the grounded conductor outwards to the transformer and travel through this back to the service overcurrent protective means and trip.
Additionally to make it comply, remove the neutral conductors from the left-hand side terminal bar (the equipment grounding bus) and relocate them to the neutral bus (which has now been effectively isolated from the enclosure assuring that return current flowing on the neutral will no longer be imposed on the egc's.

[Vern Heiler]

As I look at the close up photo provided I see no electrical connection between the "floating" equipment grounding conductor terminal on the left-hand side and the grounded conductor (neutral) terminal on the right-hand side.

Fred, isn't the big philips head screw connecting the strap that passes under the buss to the right terminal? Looks like it might be a little green.

[Fred Warner]

Fred, isn't the big philips head screw connecting the strap that passes under the buss to the right terminal? Looks like it might be a little green.

If, in fact, that is what that bolt is doing (making a connection to a strap hidden from view beneath that black plastic insulator), then I agree. It should be removed so that there is not an electrical connection between the two bars which are intended to serve entirely different functions.

In order for the panelboard to been listed and labeled, it would have to have a means to disconnect the grounded conductor from the enclosure. Typically this is done by removable straps or bolts or a combination of the two. The end configuration should be such that the equipment grounding bus is connected by strap or bolt to the enclosure which has the EMT thoroughly connected by means of fitting and locknut to the enclosure. The neutral terminal must be isolated "floating" and have no connection to the enclosure or the equipment grounding bus until it reaches the neutral bus within the main disconnecting means. :)

[Jim Port]

I think the damage is just to the nylon overcoating on the wires and not to the actual insulation on the conductors. The yellow residue is probably the leftover wire lube to make the pulls easier.

I am not seeing a grounding conductor so I will assume that the conduit is being used. With the bond strap out that would make the neutrals on the left buss incorrect.

Is this panel in the same building as the service or is it detached?

[Jerry Peck]

If, in fact, that is what that bolt is doing (making a connection to a strap hidden from view beneath that black plastic insulator), then I agree. It should be removed so that there is not an electrical connection between the two bars which are intended to serve entirely different functions.

It should NOT be removed, they are made that way by the manufacturer. BOTH the right and left terminal bars are neutral buses.

The equipment grounding terminal bar will be attached to the back of the enclosure or to the side of the enclosure (depending on where the manufacturer provided for that mounting).


In order for the panelboard to been listed and labeled, it would have to have a means to disconnect the grounded conductor from the enclosure. Typically this is done by removable straps or bolts or a combination of the two.

Which is shown as having been removed in the photo.

The best way to verify which this is if you cannot tell visually is to use a multimeter and first check voltage between the two terminal bars, if no voltage is present, check resistance between them.

With the grounding bond removed as in the photo, you should get some resistance (but not a lot) between the two terminal bars if they are not connected metallically and electrically by a bus inside the plastic insulator.

If there is a connecting bus inside the plastic insulator, you should not measure any resistance between the two terminal bars as they are connected electrically to each other.

To me ... that does not look like the ones made with two separate, independent, floating (isolated from the enclosure) terminal bars. That looks like the kind with a flat metal bus inside the plastic insulator with two upturned ends (the angled plastic ends extending up to the terminal bars) which has a connecting metal piece bent upward inside, which has a hole through which the large screw on the left is inserted to make contact with the connecting metal bus and on the right side which has a large screw into the terminal bar connecting the right terminal bar with the metal, and the neutral terminal attached to it.

The large screw on the left does not need to be removed, it was provided by the manufacturer, both terminal bars are neutral terminal bars, thus the green ground needs to be removed.

[Jerry Peck]

I think the damage is just to the nylon overcoating on the wires and not to the actual insulation on the conductors.


That "nylon overcoating" is 'part of' "the actual insulation on the conductors".

That is what helps the conductor insulation achieve the rating it has.

[Roland Miller]

Just one correction for Jerry--THHN — Indicates a single conductor having flame-retardant and heat resistant thermoplastic insulation with a jacket of extruded nylon or equivalent
material. The wire is rated 90°C dry only.

The jacket has nothing to do with the insulating properties of the conductor as noted from UL..:) It is only there for ease of pulling..

[Jerry Peck]

That is what helps the conductor insulation achieve the rating it has.


Just one correction for Jerry--THHN — Indicates a single conductor having flame-retardant and heat resistant thermoplastic insulation with a jacket of extruded nylon or equivalent
material. The wire is rated 90°C dry only.

Huh? Yeah, you agreed with me. Then you posted a contradictory ...


The jacket has nothing to do with the insulating properties of the conductor as noted from UL..:) It is only there for ease of pulling..

That outer covering is ... well ... you said it better than I did ...

"Indicates a single conductor having flame-retardant and heat resistant thermoplastic insulation with a jacket of extruded nylon or equivalent
material. The wire is rated 90°C"

And that has NOTHING to do with the insulation rating????

What would you have, say, with the same conductor insulation WITHOUT that outer covering?

[Roland Miller]

The nylon jacket is not figured into the insulation rating. You can strip it completely off and the insulation value would not change.

[Jerry Peck]

The nylon jacket is not figured into the insulation rating. You can strip it completely off and the insulation value would not change.

What would the insulation rating be without it? THHN? THN?

[Roland Miller]

The nylon jacket does have a function--it is there to protect the insulation while pulling the conductor and as a flame retardant. I didn't say it would still be listed. It would still be 90 deg at 300 or 600v though.. It is just not a factor in the actual insulation rating. A protective cover only..

[Fred Warner]

Some manufacturers of split neutral bus panelboards insulate both sides from the enclosure and provide an equipment grounding bus for egc's. It's possible that this panelboard shown is from one of those manufacturers.
Some provide insulating material on one side. As with home inspectors and electrical inspectors, it's always wise to be on the lookout for any type of field modification that would void the manufacturer's warranty....and it goes without saying that modifying a panelboard split neutral bus against the intentions of the manufacturer is a big NO NO.
My intention is to point out that interconnecting current-carrying conductors with egc's violates the code in a serious way. Current takes all paths back to it's source, not just the path of least resistance. When return current is imposed on the equipment grounding conductor objectionable voltage can be present at undesirable places like a drinking fountain for example. That blue spark that comes out to meet the unsuspecting thirst quencher may not be enough to kill, but it will certainly be unwanted.
If I have created the idea in anyone's head to modify a panel against it's listing, please be assured that is not my intention. Directions are always provided on the labels affixed to the inside walls of panelboard cabinets, but are seldom read. :)

[Jerry Peck]

The nylon jacket does have a function--... and as a flame retardant.

A protective cover only..

Make up your mind.

Either it does have a function (which is part of its rating) or it does not.

[Roland Miller]

It doesn't have anything to do with the insulation rating..

[Jerry Peck]

My intention is to point out that interconnecting current-carrying conductors with egc's violates the code in a serious way.


I completely agree with that.

The other posts, though, were referencing that particular panel.

That other panel it that other thread (topic) was an excellent example of what you are saying - that photo of the panel with the exposed metal connector bus going behind the phase bus bars from the right side to the left side, making both grounded to the enclosure, and making that enclosure ONLY suitable for use as "service equipment" - NOT suitable for use as it was being used, which was 'not-service equipment' use, simply a panel/loadcenter/distribution panel.

[Barry Lewis]

It's tough to see in these pics..but it looks like the neutral bus on the left has a GREEN bonding screw (at the top) through to the back of the panel. I don't see any connection between the two neutral bus bars. Someone please correct me if I'm wrong.... all the neutrals should be separated and isolated from the panel, the green equipment ground wire should be bonded with the conduit to the panel. This provides the appropriate two separate paths back to the main service panel. The defect I see is the neutrals on the left side should be moved to the floating neutral bus on the right side (that is if in fact it is isolated or floating). That leaves the bonded bus with the green EGC and conduit all bonded together with the neutral path separate to the main service.

[Roland Miller]

[quote=Jerry Peck;70067]I completely agree with that.

Thanks Jerry--I know you would figure it out.

[Jerry Peck]

[quote=Jerry Peck;70067]I completely agree with that.

Thanks Jerry--I know you would figure it out.

Talk about taking a post out of context, I was agreeing with something Fred said, not anything you said.

Sheesh!

[Roland Miller]

Jerry --I knew you were agreeing that the nylon outer jacket has nothing to do with the insulation value. Only the rating. You are out of context sometimes...Faster horse--I am telling you will work wonders...

[Jerry Peck]

Only the rating.

Now you are agreeing with me.


Faster horse--I am telling you will work wonders...

I know you keep saying that, and I keep waiting for you to get that faster horse ... so you can keep up. :rolleyes:


It doesn't have anything to do with the insulation rating..


It is just not a factor in the actual insulation rating.


The nylon jacket is not figured into the insulation rating.

It is, it isn't, it is, it isn't ... Roland, you really do need to make up your mind. :rolleyes:

[Roland Miller]

Yup --you got me on the insulation rating thing. The jacket doesn't figure into the insulation value.:confused:

My horse has been around three times now:p I guess I will get on it now:rolleyes:

But thanks for agreeing with me. I feel special now...:cool: I knew you would in the end..

[Roland Miller]

Yah know-Jerry your convoluted responses laced with perturbations confuse even those of us with the correct answer. :D

[John Steinke]

THHN, the most common wire used today, has an inner insulating PVC layer, as well as a nylon outer jacket.

The nylon jacket is just for ease of pulling, and has nothing to do with electrical insulation. New wire will frequently come from the factory with damaged / cracked / blisters in the nylon jacket. Or, the nylon will separate the first time the wire is flexed.

As long as the inner insulation isn't damaged, there's no problem.

[Roland Miller]

I agree--in fact amid all of Jerry's confusion, I think I may have said that..:confused: Thanks