A few technically more informed posters have provided the
responsible posts. For example, a defective neutral wire
could cause excessive voltages on one appliance when other
heavy current appliances are turned on. A common reason for
this is a loose screw where the heavy neutral wire connects
inside circuit breaker box. Other reasons would be a failing
utility transformer or badly spliced neutral in the utility
drop. But again, this would also be obvious in incandescent
bulbs dimming or getting brighter and also failing noticeable
faster.

Failed neutral is but another reason why the earth ground
rod (water pipe is no longer acceptable). also called ground
electrode connection, is important for human safety reasons.
Earthing is also why the utility transformer ground is
important ( http://www.tvtower.com/fpl.html ). Both must be
verified by visual inspection. They are responsible for
ground on that transformer. You are responsible for earthing
of the building.


A socket tester will report nothing useful. You need
numbers. No 'go-nogo' test exists for this type problem. You
are looking at electricity which means, at minimum, you need a
3.5 digit multimeter. So ubiquitous and inexpensive today as
to even be sold in Radio Shack, Home Depot, Lowes, and Sears.

Power surges are what the naive hype when they have no
idea. Destructive surges occur typically once every 8 years.
He has damaged parts. As another responsible poster noted,
best evidence is the dead body. But one problem. Most
computer repair people have little idea how electricity works
let alone be able to identify the failed part. If repairman
does not have an oscilloscope AND know how to use it, then he
would typically declare it a power surge using same
'knowledge' failure.

The tenant has a surge protector. So what? Voltages that
would typically damage electronics, as described, may be more
than 130 volts on the 120 volt outlet for prolonged periods.
Voltages that are well below a number on power strip
protectors - 330 volts. IOW surge protector would never even
see nor respond to destructive voltages that are less than 300
volts. Let us say he is suffering 150+ volts, but light bulbs
(incandescent only) are not glowing brighter. OK. Where is
that excessive voltage coming from?

Well computer is connected to AC electric and cable. Or AC
electric and phone line. Or Cable and phone line. To avoid
excessive voltage, all three must first connect to the same
earth ground before entering building - as is demanded by
National Electrical Code requirements. A CATV wire connected
to a water faucet is not sufficient. A phone connected to a
water pipe no longer qualifies. All three utilities must
connect either by direct hardwire (AC electric breaker box and
cable) to the same earth ground rod. Phone line makes same
hardwired connection via a surge protector inside the NID box.

It has been observed. Electrical failures inside an
adjacent house caused excessive voltage in this house because
the incoming utilities were not first earthed at a common
point. Just another possibility that is most easily
eliminated by visual inspection.

More things to look for. The socket tester can report a
failure BUT it cannot report a good socket. You need numbers
which means a meter. You are looking for excessive voltages
such as more than 126 volt on wall receptacle - hot to
neutral. Or more than 2 volts between receptacle neutral and
safety ground. These voltages taken under normal conditions
AND when heavy current appliances are turned on or off.

One further note - if printer and computer are not sharing
a same power strip and are therefore on different circuit
breakers. If the devices do not have good equipment grounds
(wall receptacle safety ground), then this too can create
destructive voltages between a computer and its printer. The
tenant must have a power strip, with the all so important 15
amp circuit breaker and without surge protector (adjacent
surge protector can even contribute to damage of a powered off
appliance). Basic power strip with the important 15 amp
circuit breaker costs $3+ in Home Depot or Walmart. If
printer and computer get power from different circuit breakers
(and if other criteria are met which is beyond the scope of
this text), then computer damage can result due to a 240 volt
leakage via data cable.

Hope this helps. Numerous things to inspect. A meter and
visual inspection is required. A large and well insulated
screwdriver may be necessary to tighten screws on incoming
neutral wire inside breaker box which is the best way to
confirm that connection. Best evidence would be from a list
of components - resistors, capacitors, IC - damaged in
computer and printer. Most computer repairmen don't have
sufficient knowledge to provide that information - which is
why they too always blame surges.

Thomas wrote:
Can anybody help me with this problem?

I have someone living in my apartment while I am away. He has rung me
up to say that in the last ten months THREE computers have "died" on him
due to being connected to a socket in my apartment. (I think he's
trying to make me feel guilty so that I will compensate him somehow.)

He says that on each occasion his computers have been hit by a power
surge. He says that on the first two occasions he wasn't in when the
surges hit, but that on returning home he found the computers dead. He
says that for the third computer he fitted a surge-protector between the
socket and his computer, but that last week he was at home when his
printer started "smoking". He says this last power surge must have been
really bad.

Today I rang my electricity network provider and they assured me that
there have been NO major surges in my area in the last year, and that if
there had been then the whole apartment would have been knocked out, the
fuses would have blown in the fuseboard, and other equipment and lights
would have been damaged too.

In a couple of days' time I am going to visit the apartment with a
socket-tester - it's a small plug which shows if the socket is wired
correctly. The only thing I can think of which might have caused the
death of three computers (if, in fact, they DID really die) is that the
"live" and the "neutral" wires to the socket (from the fuseboard) might
have been attached to the socket the wrong way round.

If this is the case, I know this wouldn't injure a lightbulb, but my
question is: would this injure a computer? A friend tells me that
current is "alternating" and that it therefore shouldn't matter whether
the live and neural wires to the socket are reversed. But does this
situation ring any bells with anyone?

Or is the guy in my apartment either just someone who has bought three
faulty computers in a row or someone who is just trying to take me for a
ride?

Thanks.

Nell.