APC hums (buzzes) when hair dryer is run in another room

[BE]

We live in an 80+ year old house with wiring of similar vintage (I assume).
All the computers are on UPS devices. My main computer is on an APC Back-UPS
Pro 1000 with fresh batteries, which is certainly powerful enough to handle
what's plugged into it. I will say that because there are no grounded
outlets in this house (except for one in the kitchen), the APC unit's
three-prong plug gets its 100v juice thanks to an adapter that ignores the
ground prong.

My stepdaughter runs a blow dryer in her room and when she does, my APC unit
makes a humming buzz sound for as long as the dryer is on. The unit never
beeps (as it does when there's an outage or dip in power) - it just makes
this buzzing humm.

Aside from whatever might be said of the lack of grounding (which cannot be
helped), is this buzz indicating that any damage to the computer could be
occurring?

Thanks,
Be

 

[Homer J Simpson]

We live in an 80+ year old house with wiring of similar vintage (I
assume).

Possibly knob and tube? Or steel conduit?

My stepdaughter runs a blow dryer in her room and when she does, my APC
unit
makes a humming buzz sound for as long as the dryer is on. The unit never
beeps (as it does when there's an outage or dip in power) - it just makes
this buzzing humm.

Does the dryer have a variable heat control?

Aside from whatever might be said of the lack of grounding (which cannot
be
helped), is this buzz indicating that any damage to the computer could be
occurring?

Probably not. Can you meter the supply?

 

[Meat Plow]

We live in an 80+ year old house with wiring of similar vintage (I assume).
All the computers are on UPS devices. My main computer is on an APC Back-UPS
Pro 1000 with fresh batteries, which is certainly powerful enough to handle
what's plugged into it. I will say that because there are no grounded
outlets in this house (except for one in the kitchen), the APC unit's
three-prong plug gets its 100v juice thanks to an adapter that ignores the
ground prong.

My stepdaughter runs a blow dryer in her room and when she does, my APC unit
makes a humming buzz sound for as long as the dryer is on. The unit never
beeps (as it does when there's an outage or dip in power) - it just makes
this buzzing humm.

Aside from whatever might be said of the lack of grounding (which cannot be
helped), is this buzz indicating that any damage to the computer could be
occurring?

Thanks,
Be

The APC should be grounded. You're sure it isn't switching to battery?

 

[BE]

The APC should be grounded. You're sure it isn't switching to battery?

To the extent that such a switch would be indicated by the beeping of the
unit, I am positive that it is not.

I would love to be able to ground it properly, but this is not possible. I
figure it is better than running the computers themselves ungrounded and
subject to this house's "dirty" electricity. Since I lost a computer 7-8
years ago to the abuse this house's electricity inflicted upon its power
supply, I have made it a policy to have a UPS for everything I care about:
TV, wireless internet base station and DSL modem, plus all three of our
computers. I think it's better to have these UPS units ungrounded than not
at all.

Be

 

[BE]

Possibly knob and tube? Or steel conduit?

It is copper wire with a very thick braided covering.

Does the dryer have a variable heat control?
Yes.

Probably not. Can you meter the supply?

I have metered one of the outlets in another part of the house and the
current seems to average 123 volts. Should I plug this tester into the back
of the UPS - is that what you are suggesting?

 

[jakdedert]

It is copper wire with a very thick braided covering.

Single conductor or a jacketed two conductor cable? I've seen knob and
tube wiring as you describe. When I got down to the actual conductor,
it was something like 20 gauge...very small; and this was house mains
wiring.

I have metered one of the outlets in another part of the house and the
current seems to average 123 volts. Should I plug this tester into the back
of the UPS - is that what you are suggesting?
Be

I think he's suggesting that the load of the dryer (these can consume
well over a kilowatt on high power settings) might be pulling down the
supply voltage. Try again with the dryer running. It might be on the
same overloaded circuit.

jak

 

[Dan K]

To the extent that such a switch would be indicated by the beeping of the
unit, I am positive that it is not.

I would love to be able to ground it properly, but this is not possible. I
figure it is better than running the computers themselves ungrounded and
subject to this house's "dirty" electricity. Since I lost a computer 7-8
years ago to the abuse this house's electricity inflicted upon its power
supply, I have made it a policy to have a UPS for everything I care about:
TV, wireless internet base station and DSL modem, plus all three of our
computers. I think it's better to have these UPS units ungrounded than not
at all.

Be

Ground the UPS (run a wire down the stairs to the kitchen if you have to)
and see if the buzz goes away when the hair dryer is on. If it does not,
then start looking elsewhere (temporarily try a different UPS?). If the
buzz does go away, then its a grounding problem...either find a UPS that
works better without a ground, figuring out how to ground the UPS
permanently, or forget it and see what happens.

Dan

 

[James Sweet]

We live in an 80+ year old house with wiring of similar vintage (I assume).
All the computers are on UPS devices. My main computer is on an APC Back-UPS
Pro 1000 with fresh batteries, which is certainly powerful enough to handle
what's plugged into it. I will say that because there are no grounded
outlets in this house (except for one in the kitchen), the APC unit's
three-prong plug gets its 100v juice thanks to an adapter that ignores the
ground prong.

My stepdaughter runs a blow dryer in her room and when she does, my APC unit
makes a humming buzz sound for as long as the dryer is on. The unit never
beeps (as it does when there's an outage or dip in power) - it just makes
this buzzing humm.

Aside from whatever might be said of the lack of grounding (which cannot be
helped), is this buzz indicating that any damage to the computer could be
occurring?

Thanks,
Be

Measure the voltage at the outlet the UPS is plugged into while the hair
dryer is on, it sounds like the voltage is sagging.

 

[Homer J Simpson]

It is copper wire with a very thick braided covering.

Does it run in steel conduit? If so, that is often (but not always IME) a
good ground.

Yes.

Just a switch (low-med-high) or a dial (0-9)?

I have metered one of the outlets in another part of the house and the
current seems to average 123 volts. Should I plug this tester into the
back
of the UPS - is that what you are suggesting?

No, while there is a niggling doubt that something nasty is happening you
are most probably OK.

However your wiring was intended for lighting and very light loads (radio
etc). I assume you have gas cooking and heating and not electric. If you
have a friendly electrician perhaps he could tell you his opinion of your
wiring.

 

[BE]

Does it run in steel conduit? If so, that is often (but not always IME) a
good ground.



Just a switch (low-med-high) or a dial (0-9)?


No, while there is a niggling doubt that something nasty is happening you
are most probably OK.

However your wiring was intended for lighting and very light loads (radio
etc). I assume you have gas cooking and heating and not electric. If you
have a friendly electrician perhaps he could tell you his opinion of your
wiring.

I _think_ we are OK - we have lived in this house for more than 10 years
now; if we were overtaxing the circuits they would have done something
(logic suggests) to indicate this by now. Only on a couple occasions have we
even blown a fuse. Our fuses are the old screw-in type that look like the
bottoms of light bulbs.

Be

 

[Homer J Simpson]

I _think_ we are OK - we have lived in this house for more than 10 years
now; if we were overtaxing the circuits they would have done something
(logic suggests) to indicate this by now. Only on a couple occasions have
we
even blown a fuse. Our fuses are the old screw-in type that look like the
bottoms of light bulbs.

I hear you, but sometimes people screw with this stuff. Knob and tube is
usually fine unless you get an amateur who tinkers with it. Then it is a
fire and shock risk.

 

[[email protected]]

We live in an 80+ year old house with wiring of similar vintage (I assume).
All the computers are on UPS devices. My main computer is on an APC Back-UPS
Pro 1000 with fresh batteries, which is certainly powerful enough to handle
what's plugged into it. I will say that because there are no grounded
outlets in this house (except for one in the kitchen), the APC unit's
three-prong plug gets its 100v juice thanks to an adapter that ignores the
ground prong.

My stepdaughter runs a blow dryer in her room and when she does, my APC unit
makes a humming buzz sound for as long as the dryer is on. The unit never
beeps (as it does when there's an outage or dip in power) - it just makes
this buzzing humm.

Aside from whatever might be said of the lack of grounding (which cannot be
helped), is this buzz indicating that any damage to the computer could be
occurring?

Thanks,
Be

I think there is a very simple explanation for what is going on.

The hairdryer is putting out a lot of electrical "noise" onto the
electrical power line. That noise goes through the wiring and into the
front end of the UPC and gets into the UPC power line voltage sensors
and is causing them to rapidly cycle on and off, hence the chattering
or buzzing sound from the UPC.

I would guess that the dryer and the UPC are on the same circuit, or at
least on the same 120V phase, assuming the house does have a 230V
input. The noise is most likely being conducted into the UPC, although
I would not 100% rule out radiated noise. A simple power line filter
on either the hair dryer or the UPC should fix the problem. They are
about the size of a pack of cigarettes, plug into the wall and have an
outlet into which you plug the appliance. You can also make up a crude
filter using ferrite toroidal cores. If you can get hold of a member
of the Institute of Electrical and Electronic Engineers Electromagnetic
Compatibility Society, they can help you. I am past president of that
organization and our members are always interested in these sorts of
problems.

H. R. (Bob) Hofmann

 

[T Shadow]

I _think_ we are OK - we have lived in this house for more than 10 years
now; if we were overtaxing the circuits they would have done something
(logic suggests) to indicate this by now. Only on a couple occasions have we
even blown a fuse. Our fuses are the old screw-in type that look like the
bottoms of light bulbs.

Be

My house is 100 years old. My K&T is 16 gauge. I've replaced all of the
power circuits in the house. Only using the K&T for lighting and replaced
most of the lights with CFL. The hair dryer is going to take a considerable
portion of the lines capacity. Do you know if the fuse is correct for the
wiring? Even if it is correct a bad connection can cause heat and fire
without blowing fuse. Not only are the lines light duty, to say the least,
little thought was given as to where power needed to be distributed.
Especially by modern standards. The outlet we used for coffeemaker and
toaster was 10' from fuse box but electricity came through 60' wire.

Not trying to scare you but you really should know what your dealing with
regardless of what's causing the noise. What you describe doesn't sound
like arcing but who knows. House fires are almost as common as major crimes.
Do you lock your doors at night?

 

[Eeyore]

We live in an 80+ year old house with wiring of similar vintage (I assume).
All the computers are on UPS devices. My main computer is on an APC Back-UPS
Pro 1000 with fresh batteries, which is certainly powerful enough to handle
what's plugged into it. I will say that because there are no grounded
outlets in this house (except for one in the kitchen), the APC unit's
three-prong plug gets its 100v juice thanks to an adapter that ignores the
ground prong.

My stepdaughter runs a blow dryer in her room and when she does, my APC unit
makes a humming buzz sound for as long as the dryer is on. The unit never
beeps (as it does when there's an outage or dip in power) - it just makes
this buzzing humm.

Aside from whatever might be said of the lack of grounding (which cannot be
helped), is this buzz indicating that any damage to the computer could be
occurring?

Does it only do it when the hair dryer's on low heat ?

I've come across something similar *once only ever* and it was also bad wiring.

The hairdryer uses a diode for low heat and this creates a DC content on the AC
line.

You need your wiring replaced.

Graham

 

[Meat Plow]

I _think_ we are OK - we have lived in this house for more than 10 years
now; if we were overtaxing the circuits they would have done something
(logic suggests) to indicate this by now. Only on a couple occasions have we
even blown a fuse. Our fuses are the old screw-in type that look like the
bottoms of light bulbs.

My home lacks 3 conductor wiring. I added a ground to a few outlets
(computers, ham equipment uninterruptable supplies, shop electronics) by
driving a 6" copper rod at each end of the house into the ground and then
adding them to whatever circuit I wanted. This comming spring I will
upgrade the service to 3 wire, 100 amp as it stands right now I have 4
round fuses for the entire home (2 bedroom brick with basement and
attic)60 amp.

 

[Meat Plow]

I hear you, but sometimes people screw with this stuff. Knob and tube is
usually fine unless you get an amateur who tinkers with it. Then it is a
fire and shock risk.

Ok what's knob and tube?

 

[Homer J Simpson]

Ok what's knob and tube?

http://en.wikipedia.org/wiki/Knob_and_tube_wiring

 

[Michael A. Terrell]

Ok what's knob and tube?

http://en.wikipedia.org/wiki/Knob_and_tube_wiring


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[CJT]

Meat Plow wrote:

My home lacks 3 conductor wiring. I added a ground to a few outlets
(computers, ham equipment uninterruptable supplies, shop electronics) by
driving a 6" copper rod at each end of the house into the ground and then
adding them to whatever circuit I wanted.

<snip>

Try to convince me that was a good idea. My first reaction is to think
it would potentially (no pun intended) create a colossal ground loop.

 

[Guest]

APC is probably sensing all the spikes and noise being generated by the hair
dryer, that is across the ac line.

apc units can be so well designed that they will detect any non-pure
waveform that gets induced into the circuit it is connected to. they
usually switch to battery whenever this happens, they do it so quickly u
nevr notice unless it is a repeated event, such as a 1.2kw hair dryer and
its cheap motor loading the wires in your house.

while it wont cause you any problems, it is an indication the house wiring
is inadequate for the powerful hair dryer

i am surprised the APC even works without a proper ground circuit! most
will fail to start when ungrounded.