220V dryer sparked on startup (3 wire) What to test?

[Danny D'Amico]

Now you're getting too close! :)

[Danny D'Amico]

I'll have to feel it for heat.

In daylight, I'll see if I can trace it to which circuit it feeds, and then I can feel it to see if it's hot or not.

[Danny D'Amico]

I thought they had fixed that problem. But maybe I'm grandfathered in.

[Danny D'Amico]

I'll turn the generator off, shut the 200 Amp breaker feed, and then see what I can do about the connections.

Thanks for noticing that.

[Danny D'Amico]

I have no idea if that was there when I bought the house, or, if it's new. Now, at least, I have pictures to see what changes moving forward.

[Danny D'Amico]

Actually, I've had to replace the battery, so, I had to read the manual, and I'm positive it runs exactly one week after I hit the switch.

So, I'm positive it's a 7-day thing, to the hour.

It runs for 20 minutes, to the minute.

So, at least *this* generac is dumb.

[Nightcrawler®]

Pencil may be erased if a change in the landing of the wires is performed (moving a circuit breaker for whatever reason).

We curse those who use pen. White-out is not always on board. :-)

[Danny D'Amico]

That's interesting. I'm trying to think why. I guess they want only one good ground?

[Nightcrawler®]

Checking the new angle, it would appear that you are correct. The first shot I looked at sort of hid that, or my monitor is getting so bad that I not only need reading glasses, but a new monitor, too. Probably both.

[Dean Hoffman]

Hint: Electricity follows all available paths back to its source, not just the path of least resistance.

[Danny D'Amico]

Interesting.

It makes sense that something *else* caused the scorching because if the wire that is scorched had itself gotten hot, the entire insulation would be burnt.

So,that means, as you noted, something *else* caused the scorching of the insulated wire.

There seem to be *two* bare aluminum wires that may be culprits:

Looking closer at the pictures, it seems that someone might have "repaired" a smaller black wire at the same location (by wrapping tape around it?).

However, another (even closer) picture shows that the upper bare aluminum wire does not seem to have burned the insulation on the wire below it:

Here's a picture showing the *two* aluminum wires:

BTW, what on earth are the bare aluminum wires anyway? Are they huge grounds? Are they un-insulated neutrals?

[Danny D'Amico]

I hadn't thought of that!

Thanks.

[Nightcrawler®]

It makes things easier to troubleshoot if things go wrong, and there are certain applications where it is necessary to have specific color codes. It is preferential, especially in commercial/industrial work, to have everything color coded denoting phase/neutral/ground by color and by labeling of each conductor as to which panel they originate from and to which circuit breaker they are attached to or associated with.

Example: There are five panels labeled PNL 1, PNL 2...PNL 5. Two panels have conduits that intersect in a 16x16x4 screw cover junction box. To simplify what wires are what (let us say PNL 2 and PNL 4 have

3 wires each entering, among many others). There is a black a white and a green from PNL 2, with the hot coming from circuit breaker 6. The black and white wires would be labeled PNL2 6, or PNL2 CB6. Space on PNL2 6 is intentional. The green may be labeled only PNL2. Now, the wires from panel 4 consist of three wires that are Blue, White and Green. As you may suspect, the blue and white wires will be labeled PNL4 CB#. And the green will be PNL4. The color is done to let you know what phase and type of voltage and/or to distinguish each conductor from the other. The labeling gives source location and termination point. It just makes things easier when you have to go back in and start messing with things. It is not allowed to use the wrong color of wire for a specific voltage source.

You should not see a blue wire in the power distribution of a residential system. It happens and no one really gives a rip, but on principal this is not supposed to happen. Black, red, white and green are what you should see. Poly-phase systems are another discussion. That is where you will see blue, brown, orange, yellow and purple. There are more colors, but that is still another discussion.

[Danny D'Amico]

If the neutral bars were connected to the case at the sub panels, there might be resistance between the case of the sub panel and the ground of the main panel.

If there is resistance, there will be a potential.

If that's right, what they want is for the wire from the sub panel neutral bus to be the only connection to the main breaker neutral bus, so that they *know* it is a low resistance path.

Is that right?

[Danny D'Amico]

I don't see any green tape, so, I'll look closer tomorrow in the daylight.

[Danny D'Amico]

OK. I'm happy to know that the red is another hot for the 240V lines.

Thanks for clarifying that. Right now I'm more worried about the brown scorching... :)

[Nightcrawler®]

The breaker is sized to protect the conductor attached to it. In this case a 10 gauge or larger wire. The wire is sized to provide the proper ampacity to the device being powered. If you are powering a 25 amp device you would feed that device with a 30 amp breaker as long as the device does not have an inrush current that would trip the breaker. That is an entirely different discussion. In essence, motors draw much more current on start up than when running. This is a factor in selecting proper wiring/ protective methods.

Nobody here knows.

[Nightcrawler®]

:-)

My X was a volunteer for Loma Prieta Fire and Rescue, Summit Station. I know the area (used to) quite well. I donated one of my vehicles to the fire department for one of their jaws of life demonstrations. It was pretty cool watching it get chopped up.

[Nightcrawler®]

Now that I think about it, I got it backwards. The insulated wire is cooking the non insulated wire. So much for being tired and bleary eyed. The bare wires are grounds.

[Danny D'Amico]

Yeah, I cut open doors with an air chisel, and cut circles out of windshields to remove (fake) heads which smashed through and even peeled off the roof like opening a can of sardines.

Amazingly, it's not easy to break a rear window or side window, especially if you hit it dead center with a hammer or sledge.