panel pic

[Chad Fabry]

Chad, I'm wondering how many conductors the manufacturer called for on those machines. If those were 120V work lights and not 240V, I bet it was four...or was this a DIY motor & light wiring job?

I'm positive they called for four.

3 circuits, a Bridgeport w/a 120 v worklight and 120v power feed for the table, a Clausing w/a 120v work light, and a compressor...no work light.

[Sodapop]

Originally posted by Jim Katen

Originally posted by Sodapop

Subpanel should have been fed with a 4 conductor SE cable. ( 3 ungrounded, 1 grounded). . .

Hmm, don't you mean 2 ungrounded, one grounded and one grounding?

- Jim Katen, Oregon

Only if not in a subpanel.

Ground - The Earth

Grounded (Grounding) - Connected to ground or to a conductive body that extends to the ground

Grounded Conductor - A system or circuit conductor that is intentionally grounded.

Neutral Conductor - The conductor connected to the neutral point of a system that is intended to carry current under normal conditions.

A subpanel needs to have the grounds and neutrals seperated. The bonding screw is NOT installed thereby not bonding the neutral to the ground. Since the neutral in the subpanel is not connected to ground or to a conductive body that extends to ground there would be only 1 grounded conductor. The bare ground in the SE cable would be the "intentional ground" therefore (3 ungrounded and 1 grounded).

The 3 ungrounded conductors are intentionally an ungrounded conductor. The 1 grounded conductor intentionally is a grounded conductor.

[Bryan]

Chad,

Do either of the machines have a step down transformers? It has been a while since I did industrial maintenance; however, dosn't a step down transformer produce its own neutral? 220 volts going in and 120 volts going out?

Bryan

[Sodapop]

This is what I'm trying to say in post #27

The grounded conductor is grounded only at the main panel and then must be insulated and isolated from ground at any subpanels, devices, etc.

The equipment grounding conductor can be bare and is connected to all metal parts, panel enclosures, etc., throughout the system.

If you have a bare conductor at a subpanel it is the equipment grounding conductor.

[StevenT]

Who's on first?

[Chad Fabry]

Do either of the machines have a step down transformers? It has been a while since I did industrial maintenance; however, dosn't a step down transformer produce its own neutral? 220 volts going in and 120 volts going out?

Bryan

I own or have owned a lot of equipment like these machines and the answer in my experience is no. The 120 v loads pull off one leg .

[StevenT]

Chad,

Since you have experience with these machines, have you ever had a problem because of the lack of a neutral? Or, do you feel that the difference in the eletcrical draw to be minimal and of no consequence?

All this talk about grounding, grounded, ground... earth, wind and fire has me dizzy. I believe that other than the fact that there is no neutral... and yes, there should be, that the panel is wired properly. Of course there may be a fault elsewhere related to this panel that can't be seen in the photo. So, I'll go on the pretense that all else is ok.

[kurt]

I'm going to display my ignorance......

I (quite literally) never see anything like that panel. We're a conduit town. If I saw this panel, I'd can it simply because none of the wiring materials are allowed.

Damned if I can figure out anything about it. Which conductors are supplying the thing? Which are the load? What planet am I on?

Someday I may be working someplace w/garbage like this, and I'd like to know what to say about it.

[hausdok]

Hi Kurt,

Just imagine the typical sub-panel that you usually see. Now look at this one and strip away the heavy bare wires and replace them with metal conduit connected to the box. Now, take that orange length of NM cable, strip away the insulation projecting in the box and replace the bare equipment grounding conductor on that NM cable with the metal conduit you're used to. Now the ground path is carried completely on the conduit and the enclosure. Blow the picture up and you'll see that there is a bonding strap and green screw connecting the bar to the enclosure, so it's obviously not isolated from the panel and the fact that an EGC is connected to it is also a no-no because this is a sub-panel You wouldn't have that though if this were done with conduit; with conduit the bond strap connecting the neutral bus is the no-no.

With your conduit the ground path is carried on the conduit, so you probably see neutral bars but not ground bars, no? There should have been a separate ground bar installed in the panel to accommodate that EGC you see there on that orange NM.

There should have been another conductor, a grounded (neutral) conductor, in addition to the two hots you see connected to the breakers and the ground path (bare wires). Those grounded conductors would all meet on that bar and all of the grounds would meet on the separate ground bar that would be connected directly to the panel.

Maybe the following diagram will help. Thank Mr. Electric, he passed them out last week at a class he gave. Click on the photo to blow it up.

Image Insert:

250.55 KB

ONE TEAM - ONE FIGHT!!!

Mike

[Jim Katen]

Originally posted by Sodapop

Originally posted by Jim Katen

Originally posted by Sodapop

Subpanel should have been fed with a 4 conductor SE cable. ( 3 ungrounded, 1 grounded). . .

Hmm, don't you mean 2 ungrounded, one grounded and one grounding?

- Jim Katen, Oregon

Only if not in a subpanel.

Ground - The Earth

Grounded (Grounding) - Connected to ground or to a conductive body that extends to the ground

Grounded Conductor - A system or circuit conductor that is intentionally grounded.

Neutral Conductor - The conductor connected to the neutral point of a system that is intended to carry current under normal conditions.

A subpanel needs to have the grounds and neutrals seperated. The bonding screw is NOT installed thereby not bonding the neutral to the ground. Since the neutral in the subpanel is not connected to ground or to a conductive body that extends to ground there would be only 1 grounded conductor. The bare ground in the SE cable would be the "intentional ground" therefore (3 ungrounded and 1 grounded).

No. That's not correct. Just because the neutral is not connected to the ground in the sub panel, that doesn't suddenly make it an ungrounded conductor. It's still connected to the ground at its point of origination. It is a grounded conductor. The fact that it floats in a subpanel doesn't change that.

- Jim Katen, Oregon

[Jim Katen]

Originally posted by kurt

I'm going to display my ignorance......

I (quite literally) never see anything like that panel. We're a conduit town. If I saw this panel, I'd can it simply because none of the wiring materials are allowed.

Damned if I can figure out anything about it. Which conductors are supplying the thing? Which are the load? What planet am I on?

Someday I may be working someplace w/garbage like this, and I'd like to know what to say about it.

Does this help?

- Jim Katen, Oregon

Image Insert:

169.14 KB

[Richard Moore]

Originally posted by Chad Fabry

Chad, I'm wondering how many conductors the manufacturer called for on those machines. If those were 120V work lights and not 240V, I bet it was four...or was this a DIY motor & light wiring job?

I'm positive they called for four.

3 circuits, a Bridgeport w/a 120 v worklight and 120v power feed for the table, a Clausing w/a 120v work light, and a compressor...no work light.

Getting back to that...

That was what I was wondering about. If the machines only called for, and had the connections for, two hots and a ground then you would still expect the bare grounding conductors to be connected to the grounding bar even if the sub-panel was wired correctly with a neutral feeder, a floating neutral bar and a separate grounding bar. In that case, any neutral current from the 120-volt work-lights would still be travelling back to the main panel via the EGC. If they do call for 4 conductors, as it seems they should, then it's not just the sub-panel that is wired wrong but also the circuits from the sub-panel to the machines.

Frankly, "neutral current" is a bit of a mystery to me. I understand that it's there but I don't really get why it's not wasted when it eventually goes to ground. But that's OK; I've also never been comfortable with the fact that you can convert mechanical power, push it along a copper line with no moving parts, and then convert it back to mechanical power. It's like...ummm...magic! Fortunately, I know just enough to know electricity is dangerous if not used correctly.

However, like Steven T, I'm also curious about the dangers of neutral current. We all frequently see and call improperly wired sub-panels with mixed neutrals and grounds but I don't think I've ever heard of anyone getting electrocuted (killed) by it. Does it happen?

[Chad Fabry]

Since you have experience with these machines, have you ever had a problem because of the lack of a neutral? Or, do you feel that the difference in the eletcrical draw to be minimal and of no consequence?

Hi Steven,

150w isn't minimal current. 1/25,000th of 150w load will trip a GFCI.

If you become the return path of a 150w circuit, you'll be dead.

[StevenT]

OK Chad,

Thank you for answering my question. Let's take it further.

What effect will this configuration have on the system? On the machinery?

Will the conductor that is being used to energize the light will run hot?

Also, I'm trying to picture how the light is wired. Since there is only hot (2) and ground, is the neutral of the light hooked up to the ground? I can't see any other way of doing it. In which case, any time the light is on, the grounding conductor and anything attached to it is energized and anyone that touches any part of the grounding system or anything it is bonded to... including the machine is going to get zapped.

Why doesn't the breaker trip?

[Chad Fabry]

Also, I'm trying to picture how the light is wired. Since there is only hot (2) and ground, is the neutral of the light hooked up to the ground? I can't see any other way of doing it. In which case, any time the light is on, the grounding conductor and anything attached to it is energized and anyone that touches any part of the grounding system or anything it is bonded to... including the machine is going to get zapped.

Why doesn't the breaker trip?

The current takes the path of least resistance; the wired path back to the service panel is a very good, low resistance path so the current will have no incentive to travel through a person, through a pair of shoes to a concrete floor.

Add some water to the equation or interrupt the return path wiring and all bets are off. The panel enclosure or uninsulated ground being used as a neutral could well present a hazard.

This situation isn't that different from the mis-wired subs we see all the time where the neutral isn't isolated from the panel .

The breaker doesn't trip because it carries the sum of the loads just like it always does. If the return path is interrupted, then there is no load... the machine or light won't work. If there is a return path, as far as the breaker is concerned, all things are normal. The breaker doesn't care whether the return path is insulated or bonded to a panel enclosure or is the panel enclosure. Heck, the breaker doesn't even care if the return path is you.

[kurt]

Originally posted by Jim Katen

Does this help?

- Jim Katen, Oregon

Immensely.

Katenization could save the world.

[Jim Katen]

Originally posted by Richard Moore

. . . If they do call for 4 conductors, as it seems they should, then it's not just the sub-panel that is wired wrong but also the circuits from the sub-panel to the machines.

Yes. I believe that I pointed this out in post #20.

Frankly, "neutral current" is a bit of a mystery to me. I understand that it's there but I don't really get why it's not wasted when it eventually goes to ground.

It doesn't go to ground -- at least not to the earth. It goes back to the center tap of the transformer's secondary coil. Think of an electrical circuit as a big circle (circle -- circuit, get it?). Electricity is constantly pulsing through that coil. If you have a circcuit that's connected to each end of that coil, you've got 240 volts. If you have a circuit that's connected to one end of the coil and the middle, you've got 120 volts. It's that simple.

We connect a grounding wire to that center tap so as to give lightning surges a place to go. If someone were to disconnect the grounding connection from the neutral, the electrical system would still work just fine. However if lightning (or some other large surge) were to strike that massive jolt would finding its way to ground all over the place instead of through the grounding electrode system.

But that's OK; I've also never been comfortable with the fact that you can convert mechanical power, push it along a copper line with no moving parts, and then convert it back to mechanical power. It's like...ummm...magic! Fortunately, I know just enough to know electricity is dangerous if not used correctly.

It's even more magical than you describe. Remember that there's no physical connection between the wire at the power plant and the wires in your house. Your house wiring gets every scrap of its power from a pulsing magnetic field inside the transformer. Look Ma! No hands!

However, like Steven T, I'm also curious about the dangers of neutral current. We all frequently see and call improperly wired sub-panels with mixed neutrals and grounds but I don't think I've ever heard of anyone getting electrocuted (killed) by it. Does it happen?

You've got two questions in there. In a properly wired circuit, the neutral is carrying just as much current as its corresponding ungrounded conductor is (multi-wire circuits aside). Because the neutral is grounded at its origination point, it *seems* safe because of the low potential between the neutral and the ground. This seeming safety sometimes leads people to get careless and put themselves in a position where they put their bodies or parts of their bodies in series with the neutral. When this happens, the victim is always surprised and his last though is either, "but it's only a neutral," or, "D'oh!" I've heard it said that more electricians are killed by neutral current than by any other kind. I have no idea if this is true or not.

The second question in there has to do with current that is normally supposed to flow over the neutral instead flowing over the grounding wire(s). We've talked about that a lot here in the past and I'll return to it later.

- Jim Katen, Oregon

[Jim Katen]

Originally posted by Chad Fabry

. . . The current takes the path of least resistance; the wired path back to the service panel is a very good, low resistance path so the current will have no incentive to travel through a person, through a pair of shoes to a concrete floor. . .

That's not quite correct. The current takes every path available to it in proportion to each path's resistance. And that's the danger in having current on the grounding conductor. The resistance of each path can change as all sorts of other conditions change. Sometimes conditions change enough for you to feel a tingle and other times they change enough for a full blown zap.

- Jim Katen, Oregon

[Chad Fabry]

That's not quite correct. The current takes every path available to it in proportion to each path's resistance

Thanks for that.

[Sodapop]

Originally posted by Jim Katen

Originally posted by Sodapop

Originally posted by Jim Katen

Originally posted by Sodapop

Subpanel should have been fed with a 4 conductor SE cable. ( 3 ungrounded, 1 grounded). . .

Hmm, don't you mean 2 ungrounded, one grounded and one grounding?

- Jim Katen, Oregon

Only if not in a subpanel.

Ground - The Earth

Grounded (Grounding) - Connected to ground or to a conductive body that extends to the ground

Grounded Conductor - A system or circuit conductor that is intentionally grounded.

Neutral Conductor - The conductor connected to the neutral point of a system that is intended to carry current under normal conditions.

A subpanel needs to have the grounds and neutrals seperated. The bonding screw is NOT installed thereby not bonding the neutral to the ground. Since the neutral in the subpanel is not connected to ground or to a conductive body that extends to ground there would be only 1 grounded conductor. The bare ground in the SE cable would be the "intentional ground" therefore (3 ungrounded and 1 grounded).

No. That's not correct. Just because the neutral is not connected to the ground in the sub panel, that doesn't suddenly make it an ungrounded conductor. It's still connected to the ground at its point of origination. It is a grounded conductor. The fact that it floats in a subpanel doesn't change that.

- Jim Katen, Oregon

When I wrote post #27 I tried reading too much into the Code.

I tried to correct my post #27 with post #29 and hope that I clarified my position.

[Sodapop]

Originally posted by Jim Katen

Originally posted by Sodapop

Subpanel should have been fed with a 4 conductor SE cable. ( 3 ungrounded, 1 grounded). . .

Hmm, don't you mean 2 ungrounded, one grounded and one grounding?

- Jim Katen, Oregon

I now stand corrected by this and other forums. I should have said: 2 ungrounded, one grounded and one grounding.

Learning something every day.

[Jim Katen]

Originally posted by Sodapop

. . . I now stand corrected by this and other forums. I should have said: 2 ungrounded, one grounded and one grounding.

Learning something every day.

I promise to correct your mistakes if you promise to correct mine. . .

We're all here to learn.

- Jim Katen, Oregon

[Richard Moore]

It doesn't go to ground -- at least not to the earth. It goes back to the center tap of the transformer's secondary coil...etc.

Y'know, I've been under that misconception since I first heard the neutral called a grounded conductor going back to the grounded transformer. I won't pretend to fully understand the whole shebang but I think at least some fog has finally lifted! Thanks Jim.

The second question in there has to do with current that is normally supposed to flow over the neutral instead flowing over the grounding wire(s). We've talked about that a lot here in the past and I'll return to it later.

That part, the need to isolate the neutrals from grounding in a sub-panel etc, I get. As weak as my electrical theory is, I can understand the physical connections needed to keep the neutral current insulated. So...you don't have to go there for me. But, many thanks for the rest of your reply.

[Sodapop]

Originally posted by Jim Katen

Originally posted by Sodapop

. . . I now stand corrected by this and other forums. I should have said: 2 ungrounded, one grounded and one grounding.

Learning something every day.

I promise to correct your mistakes if you promise to correct mine. . .

We're all here to learn.

- Jim Katen, Oregon

Will do my best.[:-graduat