Electrical Circuit Gurus---please help

[calpha]

Hey All,

I probably should have restructured the below link a little bit and posted it here instead of Off-Topic, but I didn't really have the questions until I had a little time to reflect. I was just happy as Crap that nothing important was lost, and was more focused then on sharing with others then figuring out what questions I still had.

Anyway. The LOOOOONG Post from me is below, and I have electrical Questions following for you circuit gurus: You'll have to read the post to be able to relate to my questions.
Surges Fried

1. My Office, and Kitchen were on two separate breakers, but the wire was actually looped from the Kitchen Circuit to my office circuit. So, when we cooked, and had my computers running, the kitchen circuit would trip, and the office circuit would be out (but not tripped). Is this a logical behavior, or should that have told me something was amiss as well? Both circuits are 15 AMPS on the breaker, and the stove is not included in the above mentioned circuit.

2. Are there any tools you can use to detect what happened to me preventatively, or is that something that has to happen before it can be fixed or detected?

3. Any difference electronically between a Surge Protector with AVR , or the surge protector section of a UPS with AVR (Automatic Voltage Regulation)? AVR is key to preventing system damage, correct? Would you assume that the UPSes would have fried just the same as the surge protectors had they been plugged directly into the socket?

4. Electricity runs from the + to -. If the circuit is broken then electricity won't flow. How does a neutral fit in? If you're answering this you've probably forgotten more about electricity then I'll ever know (hey I passed Phys 300 (Electricity and Circuits) a loooong time ago).
When the neutral jumped, what was it that really happened?

Thanks,
Chris

 

[rimshaker]

The AVR feature helps in preventing wear and tear caused by voltage fluctuations, so you basically get more consistent (clean) power. The correct way to use a UPS unit is to actually plug it straight into the wall socket, not through an intermediate strip... think of it as a 'bottleneck.' The 3-prong configuration is hot (+), neutral (-), and earth ground (the round prong). Obviously with the neutral disconnected, there's no power. You might be confusing neutral as ground. Technically, it is the ground (-), but only as the return path to complete a circuit. The round prong is the one that is added for safety... it's the true earth ground, and it's used to connect any device chassis connected at a socket to earth ground. This avoids any potential voltage differences, where it could shock someone.

 

[calpha]

So, if the Neutral jumped, and became a ground with the wire hot, would that be what caused the wire to burn, and the surge protectors to fry?

Thx for the nfo on AVR. that makes more sense to me now

 

[rimshaker]

Yea, if the hot (+) and neutral (-) wires touched, not a good thing. That's when the fuse blows, sometimes worse if the current load is very high at the same time. Remember, what causes any damage is the current itself, not the term 'voltage.' A bigger voltage simply means a larger amount of current can flow. Voltage won't kill you.... current will. It's also what causes any burning of the wires... current. Unfortunately, APC and any other power protection company don't cover incorrect internal wiring as valid for claims. That's something out of their jurisdiction and control. They actually do give out money or replacements should something happen, but they require you to send in the APC unit first. AFter they confirm it was a unit failure, they'll ask you to send them all the damaged items. I'd be pissed about the shipping charges... i think you're responsible for the shipping

 

[rimshaker]

Just curious, did you notice the wiring fault indicators on the back of the APC units? Were they on? Did the surge strips have fault indicators on them?

 

[calpha]

No there was nothing on the surge protectors that indicated a fault.

Like I said in the long post i linked, the power did flicker every so often in my office, but the UPSes would beep, and then go back to normal.

And, BTW. For those that didn't read the Looong post, the only thing I lost was 3 surge protectors.

BTW....can someone answer my questions about whether or not they think the UPSes would be hosed if they hadn't been plugged into a surge protector first (at least the Surge Protection circuit of the UPS?)

 

[rimshaker]

<< No there was nothing on the surge protectors that indicated a fault. >>



I'm willing to bet that if the UPS's were connected directly to the wall, it would've indicated a wiring fault. One of the reasons why they must be connected to the socket with nothing in between.

Sounds like the fried surge protectors got a huge current load, enough to destroy more than the breaker switch inside. If any current is strong enough AND also lasts long enough, arcing at the switch will melt anything after the switch. This rarely happens since the voltage/current spike has to be long enough in time duration to jump that open (tripped) switch. Yes, the UPS units would've probably been fried too, at least the surge part. But if they're still under warranty, you could get them replaced. Even if a UPS was out of warranty, better to lose $200 than $2000 worth of stuff.

 

[highwire]

You have a muddled story about two separate circuit being somehow tied together. This is the long and the short of defective neutrals:

Two circuits fed from opposite lines and sharing an open neutral will be in series and the heavy loaded circuit will cause most of the 240 volts total to appear across the lighter loaded 120 volt circuit. The saga will vary at this point, depending on the nature of the loads. In your case, the overvoltage stuff died trying to doing its job.

A related sea story:
I arrived at Port Hueneme one dark, foggy night for some ocean work, but the Navy Craftmaster said the electricity was "all messed up" on the boat. In order to make the cabin lights work at all, they had to turn on the electric oven in the gally! Yours truly, knowing about neutrals, quickly found the defective open in the shore power neutral connection, amazing the local talent and allowing us to get underway in short order. I told them that all Air Force people knew this stuff, no big deal.