Surge Problem

[A/A Fuel GTX]

I have situation where a 120V, 15A air compressor was plugged into a receptacle that was part of a branch circuit that also fed a computer. The homeowner claims that the computer was electrically damaged due to the compressor being used continuously on the day this occurred. The 20A circuit breaker tripped once during that day and no other irregularities were noted. My question is could the LRA surges caused by the continuous cycling throughout the day have caused this computer to sustain damage? If the computer was on another branch circuit separate from the compressor circuit, could there still be consequences? I'm trying to gather all possible information on this before coming up with a verdict.

 

[bdarnell]

I suppose anything is possible, but it's not very likely IMO. PC's are really pretty rugged despite what the IT gurus would have you believe.

What could have happened is if the breaker tripped and killed the PC when it was writing something to the HD, it could have corrupted data. Or, if the PC was shut down abruptly and then powered up at the same moment that the compressor came on line, a transient could have gotten it.

Like I said, I guess it's possible. I'd recommend a whole-house TVSS at the panel just as a CYA.

 

[Mike03a3]

What are the PC's symptoms and what evidence is there of it being "electrically" damaged?

While I am aware of statistics that show a significantly higher failure rate for PC's exposed to potentially unreliable power, this has generally been ones that were run in the field using motor gensets for power. Even then, the resulting failure is usually the power supply. Is the PC completely dead, or does it power up? If it powers up, does it complete the POST? I would be very surprised if voltage surges from other line loads caused physical damage.

 

[A/A Fuel GTX]

The computer was off when this occurred. PC worked fine until this incident. Homeowner claims to have taken the PC into Best Buy and they confirmed a blown power supply and motherboard. Also claims to have IT people at work who are backing up his claim that the compressor surges would be enough to do the damage. I've been placed in the middle here between the company that used the compressor and the homeowner.

 

[charlie b]

You are describing this transient with the word "surges." To be clear, what surges is the current, during the motor's starting cycle. For a short while, the system voltage will be dragged down. I don't know electronics, but I think it is possible that the low voltage is what caused damage. If for example the power supply has a voltage regulator to offset any minor changes in voltage from moment to moment, that device would be overtaxed by the voltage dip during a motor start cycle. If this damages the voltage regulation circuit, then the output voltage of that circuit could do anything. It could even send a fatally high voltage to all the computer's sensitive circuits.

All I am saying is that the computer failures might be caused by the starting of a motor. But I will add that I find it surprising that this failure could occur with the computer shut down.

 

[shelco]

I would think that a compressor on the same 120 circuit would continuosly
drop the voltage every time it starts, this will over time affect the computer, it would be almost impossible to tell if this is the cause or not.

Although some people will blame this type of stuff on any thing and some people will believe almost anything.
I was called to a home when the owner said her computer was fried due to surges, that is what her son said. I got there and the tower was covered in a sticky substance. She said her son told her that when the computer gets fried like that it emits this stuff, it is melting the inside. I said unless the computer was made of root beer I think found the problem.
She thanked me and said some one is going to pay.

 

[hbiss]

[took] the PC into Best Buy and they confirmed a blown power supply and motherboard. Also claims to have IT people at work who are backing up his claim that the compressor surges would be enough to do the damage.

I would believe my dog before I believed those idiots.

Simple truth is the power supply went taking the mother board with it. Probably nothing to do with the A/C. S**t happens, that's all there is to it.

To be on the safe side use a good quality UPS.

-Hal

 

[dlhoule]

The computer was off when this occurred. PC worked fine until this incident.

Define off. When my computer is off I have no power to power supply, and I don't care how much you run compressor or anything else unless you burn contacts on my switch closed somehow, you won't affect my power supply.

 

[tshea]

Somebody wants a new computer and they don't want to pay for it!

Setup a demonstration using a table lamp and the compressor. The compressor will not damage the table lamp. You will probably see a change in the brightness of the bulb due to momentary voltage drops when the compressor starts.

Believing the shmucks at Best Buy is like believing the aisle attendedant at Big Orange when you are getting the material to upgrade your service

 

[A/A Fuel GTX]

Thank you all for your insights. I replied to the contractor who had me evaluate this and he decided to just file an insurance claim with his carrier to have this computer repaired or replaced. He feels it's worth it to keep the peace with the customer even though it couldn't be proved conclusively one way or the other.

 

[steve66]

I think the insurance carrier will probably tell him this is bunk. And I agree. If the switch was off, then it would be almost impossible for the the compressor to affect the computer.

I used to work on fax machines. After being plugged in for 3, 4, or 5 years at a time, I would unplug them to clean them. In a small percentage, the power supplies would self distruct apon applying power. I think it had something to do with the large electrolytic capactiors suddenly being discharged and charged after years of constant on.

I think it is more likely that turning the computer on and off fried it.

Steve

 

[gardiner]

Please be aware that the a lower voltage can cause problems with "some" computers. If the power supply voltage is reduced low enough the fan on the supply will not operate at the required speed this in turn will prevent cooling and in turn will affect the Motherboard. This can happen mostly in penitum 4's and in particular mostly with 2.2 to 2.4 gig processers in some of the "bastard" brands and not usually with the top line models, as the lower line models have a tendency to install power supplies that are borderline as to their capabilities, usually leftovers from the pentium 3's. The so called experts won't always admit to this this but in most acases if your asked to check a line voltage saying it is damaging a computer I will bet it fits the description I put in above.