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hausdok

A Mr. Electric Electrical Quiz

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Hi All,

Jim Simmons - user name Mr. Electric - has sent me some photos for the brethren to look at. This is a quiz and is meant to help educate the newer folks.

Vets - let's call vets those with more than five years experience - instead of jumping in to flex your muscles and display your electical prowess, how about not responding for a while and give the newer folks time to try and figure this out; say, until about 6:00 pm PST? If by then we haven't had any comments or nobody thinks they've figured it out, then all veteran inspectors can jump in and have at it.

I'll publish Jim's answers tomorrow.

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Question: The sub-panel depicted in the photos below is wrong. Besides the fact that these panels are Zinsco brand panels, what exactly are the issues if any that you can see here?

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tn_201123151137_SimmonsTest1_1.jpg

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tn_201123151249_SimmonsTest1_2.jpg

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tn_201123151320_SimmonsTest1_3.jpg

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Thanks Jim!!!

ONE TEAM - ONE FIGHT!!!

Mike

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the pictures are too small.

Any chance Mr. Electric can re-send some bigger pics?

If this were Jeopardy, the answer would be "what did the reporter say to Bret Favre?"

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Mike, the pictures are too small.

Any chance Mr. Electric can re-send some bigger pics?

Hi,

Yeah, I see that. I think I've fixed them. He sent those to me in something called Silverlight and it took me a long time to figure out how to convert them to JPEG. Hope this works.

I don't get the Brett Favre reference. Maybe it's because I don't follow football or watch celebrity gossip programs. Maybe it's 'cuz I'm too dim witted. It's probably the latter.

ONE TEAM - ONE FIGHT!!!

Mike

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The first thing that comes to mind is not enough clearance in front of it. Some double taps, and what looks like a shredded ground wire. They are hard to see.

Do I get bonus points for understanding Chad's LITTLE joke?

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The pictures are far too small, but here's what I've got so far:

Pic 1. There is inadequate working space in front of the sub, there may not be enough for the other panel either.

Pic 2. There are several cable clamps missing, most notably on the sub panel feeders. There are also several lugs on the neutral buses where multiple wires terminate, I can't tell how many because the pics are too small to count them all.

Pic 3. The bottom of the sub panel is contaminated with something, drywall dust maybe? I can't tell for sure, did I mention the pics are too small? I only see two feeders in the sub, and what might be a grounding electrode at the bottom center of the accessory bus. I don't see a proper return path for the neutrals or the equipment grounds. I'm amazed any of the circuits in that sub work at all.

If I'm wrong blame it on the small pics.

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Agree with the small pics....

Open knockouts

missing cable clamps

limited access at subpanel

many double tapped neutral and ground wires in the main panel

what's up with the neutral conductors on the sub panel?

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I wouldn't be able to say with certainty that the sub-panel feeders were missing strain-relief clamps because of the pixilation and the ground wire in the lower gutter.

Was it Tom who mentioned that the photos are too small?

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The pictures are still a bit small, but here's what I can make out in the sub panel.

Only a 3 wire feed, there is no neutral from the main panel.

White wires used as hot conductors.

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There's something very interesting about the two hot conductors that run between the panels. (And you don't need bigger pictures to see it.)

- Jim Katen, Oregon

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Hi Guys,

Look, I'm real sorry about the size of the photos but that's the size he gave me. Here's what I suggest you do; open the photos, right click them and then save them on your own computer, open them and then blow them up to your heart's content.

ONE TEAM - ONE FIGHT!!!

Mike

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Ok, it's after 6 PST, I'll take a shot.

I believe all the subpanel branch circuits are 240V, hence no neutral feeder from the main.

1. There are no handle ties on any of those breaker handles.

2. The bending radii on the feeders is way too sharp.

3. Both feeders should exit and enter thru the same knockout. Why? Because I've never seen it done any other way, until now.

4. All the white wires should be marked black or red. (But that is a newer code rule, I believe, so does not apply if this is an old installation.)

5. They are using the neutral bus at the bottom, bonded to the panel, for a grounding bus. This is a poor choice, but I don't know if there is a NEC rule that addresses this.

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Ok, it's after 6 PST, I'll take a shot.

I believe all the subpanel branch circuits are 240V, hence no neutral feeder from the main.

1. There are no handle ties on any of those breaker handles.

Actually, there are. They're the little grey things on every other breaker handle.
2. The bending radii on the feeders is way too sharp.

3. Both feeders should exit and enter thru the same knockout. Why? Because I've never seen it done any other way, until now.

When the conductors run together, their electro-magnetic fields cancel each other out. When they're run separately, the fields remain intact. If you pass a single wire through a metal plate and run current through it, these fields can cause the metal to heat up. Its the same reason why we want both wires in a knob & tube circuit to enter a box through the same hole.
4. All the white wires should be marked black or red. (But that is a newer code rule, I believe, so does not apply if this is an old installation.)
I suspect that the rule requiring the re-identification of white wires in this situation is quite an old one. I know it was required in the '47 NEC. Even so, it seems to have been one of the more widely ignored rules.
5. They are using the neutral bus at the bottom, bonded to the panel, for a grounding bus. This is a poor choice, but I don't know if there is a NEC rule that addresses this.
I don't know of one, but there might be something in the manufacturer's literature. Unless the panel someday needs to have a neutral added, I can't imagine how it would be a problem.

- Jim Katen, Oregon

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I don't know of one, but there might be something in the manufacturer's literature. Unless the panel someday needs to have a neutral added, I can't imagine how it would be a problem.

Let's assume for a moment that these breakers feed machining equipment, not electric heat.

Some of the machine equipment has 120 volt motors to drive the tables and 120v lighting. What's going to happen then?

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Good morning everyone.

OK, here are Jim's answers:

There are several issues.

1) The feeder wires (from the breaker in the main panel to the sub-panel) are not in conduit. You can see it by following the 2 wires off the circuit breaker (in the main panel) to the bottom of the panel. This is should always be called out.

2) The wires feeding the sub-panel are not properly grouped (there are 3). They are required to all run together in one conduit or cable.

3) The feeder requires a neutral to be run with the other wires (there should be 4 wires). The neutral is required to be there even though all the circuits are for heat (240v) and don't need the neutral. The neutral (white wire) would be floated in the panel (not connected to the grounds or the enclosure).

A two wire feed plus a ground is actually legal if there are only 240v loads (as in this case), but 99.9% of the time the panel is also used for 120v, so it's best not to judge it based on whether it's only a 240v load. The best thing to understand is that the normal way for these circuits to be installed is with a four wire feed.

4) There is a clearance issue with the sub panel (needs 3' of clear space in front of the panel). Not a huge issue for this situation because you do have reasonable access and it is existing.

A few notes.

1) No main breaker is required in a sub-panel (as long as it is in the same building).

2) You should always see the 4 wire feed in conduit or in one cable (look at where the wires leave or enter the panel)

3) If you have a question (electrical) while looking at a job give me a call on my cell 360-280-8346 or office 360-705-4225

Happy inspecting!

Jim P. Simmons

Mr. Electric

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I don't know of one, but there might be something in the manufacturer's literature. Unless the panel someday needs to have a neutral added, I can't imagine how it would be a problem.

Let's assume for a moment that these breakers feed machining equipment, not electric heat.

Some of the machine equipment has 120 volt motors to drive the tables and 120v lighting. What's going to happen then?

In order to consider your assumption, we'd need to see neutral wires at the branch circuit wiring. There are none. If the branch circuits required neutrals, then the feeder should include a neutral. Since they don't, it doesn't.

- Jim Katen, Oregon

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. . . 3) The feeder requires a neutral to be run with the other wires (there should be 4 wires). The neutral is required to be there even though all the circuits are for heat (240v) and don't need the neutral. The neutral (white wire) would be floated in the panel (not connected to the grounds or the enclosure).

A two wire feed plus a ground is actually legal if there are only 240v loads (as in this case), but 99.9% of the time the panel is also used for 120v, so it's best not to judge it based on whether it's only a 240v load. The best thing to understand is that the normal way for these circuits to be installed is with a four wire feed. . . . [/i]

This might be the first time I've disagreed with Jim on an electrical issue. If the two wire feed w ground is "actually legal if there are only 240v loads" how can the neutral be "required to be there" ?

I agree that the installation in the pictures is crap for all of the other reasons cited. But I've seen lots of 240-volt panels without neutrals and I can't find anything in the NEC that would prohibit this practice.

- Jim Katen, Oregon

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Hi Jim,

He knows I was going to post his quiz on TIJ; so maybe Jim will stop by to see how folks are responding and he'll chime in.

Brandon, I've got a couple ideas. Let me see what I can do about scrounging up a weekly quiz by a plumbing expert.

ONE TEAM - ONE FIGHT!!!

Mike

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