Electrical code Compliance - Filter available?

Author

Filter available?

Tom Haley

2007-02-25, 5:25 pm

I recently noticed that all of the lights in my home flicker from time to
time.
I have isolated it to those times when my 120 VAC automatic washing machine
is in its agitator cycle.
Is this a common problem?
Are there in-line filters available that can reduce this effect?

hrhofmann@att.net

2007-02-28, 3:25 am

On Feb 25, 2:27 pm, "Tom Haley" <haley-...@comcast.net> wrote:
> I recently noticed that all of the lights in my home flicker from time to
> time.
> I have isolated it to those times when my 120 VAC automatic washing machine
> is in its agitator cycle.
> Is this a common problem?
> Are there in-line filters available that can reduce this effect?

Do the lights flicker just once each time the cycle is started, or
continuously? What level of service do you have, 120V or 240V, and at
what amperage? It is not normal for a washing machine motor to draw
enough current to make the lights flicker in a house with adequate
wiring. It could be a badly grounded neutral, or undersized
conductors. Are you familiar with how a house is fed 240V
centertapped with the center tap being the neutral? Do all the lights
get brighter, dimmer, or do some circuits get brighter and some
dimmer?

H. R. (Bob) Hofmann

Tom Haley

2007-02-28, 3:25 am

Continuously.
The service is 240v centertapped.
Neutral is good and well grounded. Good 120V reference to each leg.
Branch circuit is a rated 20A with 12 AWG copper conductors. It is a
dedicated circuit with no other loads other than the washer.
Circuit breaker is sized appropriately
Total length of branch circuit conductors is less than 40 feet.
The cycle of the flickering lights appears to coincide with the reversal of
the agitator (1-2 seconds)
Connections at the panel and the receptacle are tight.
I haven't measured the actual current draw of the motor. That may be
worthwhile.
<hrhofmann@att.net> wrote in message
news:1172637146.206328.85920@k78g2000cwa.googlegroups.com...
> On Feb 25, 2:27 pm, "Tom Haley" <haley-...@comcast.net> wrote:
to[color=darkred]
machine[color=darkred]
>
> Do the lights flicker just once each time the cycle is started, or
> continuously? What level of service do you have, 120V or 240V, and at
> what amperage? It is not normal for a washing machine motor to draw
> enough current to make the lights flicker in a house with adequate
> wiring. It could be a badly grounded neutral, or undersized
> conductors. Are you familiar with how a house is fed 240V
> centertapped with the center tap being the neutral? Do all the lights
> get brighter, dimmer, or do some circuits get brighter and some
> dimmer?
>
> H. R. (Bob) Hofmann
>

hrhofmann@att.net

2007-03-02, 1:25 pm

On Feb 28, 1:40 am, "Tom Haley" <haley-...@comcast.net> wrote:
> Continuously.
> The service is 240v centertapped.
> Neutral is good and well grounded. Good 120V reference to each leg.
> Branch circuit is a rated 20A with 12 AWG copper conductors. It is a
> dedicated circuit with no other loads other than the washer.
> Circuit breaker is sized appropriately
> Total length of branch circuit conductors is less than 40 feet.
> The cycle of the flickering lights appears to coincide with the reversal of
> the agitator (1-2 seconds)
> Connections at the panel and the receptacle are tight.
> I haven't measured the actual current draw of the motor. That may be
> worthwhile.<hrhofm...@att.net> wrote in message
>
> news:1172637146.206328.85920@k78g2000cwa.googlegroups.com...
>
>
>
> to
> machine
>
>
>
> - Show quoted text -

Is this something that only happens with this washing machine, as
opposed to a previous machine? Do all the lights in the house
flicker, or only those on the same side of the 240V centertapped
circuit, assuming you are in the USA? Do the lights get brighter or
dimmer when the motor appears to draw additional current.? All of
these things are clues as to what is actually happening.

H. R.(Bob) Hofmann

Jeff Miller

2007-04-12, 3:25 am

Hmmm... well keep in mind that when the motor reverses there is a strong
inrush of initial current.... it's not that unusual for a vacuum cleaner to
dim all the lights for a moment when it first starts, and there's a pretty
strong analogy between that and your washer motor reversing. Actually your
motor may not be reversing, or even start-stopping, but the motor is
stressed a lot when the reversing gears click back and forth. You might also
want to investigate the condtion of the motor starting circuit, IE the
start/run caps and/or centrifugal or voltage sensitive switch that cuts out
the starter cap.

That having been said, I've never heard of a washer doing that. Because the
washer is on a dedicated circuit, the voltage drop you are getting is
somewhere between the panel and, well, your utility company. Perhaps the
connection to your meter is loose, the service drop is undersized, or you
are a long way from the nearest transformer. Perhaps the sliding contacts of
the meter itself are corroded. Unfortunately you can rarely diagnose these
problems yourself because the meter box is sealed. If your meter box is
separated from your panel (like mine) you can certainly make sure the
connection to the panel is tight and of sufficient gauge. If the effect is
pretty dramatic the power company might not mind taking a look at their
side, if there is a point of high resistance it could represent a fire
hazard, and in any case excessive voltage drop is criminally inefficient
(against code). Have you ever noticed the box or perhaps the main breaker
getting hot? If I were you I might measure the voltage at the breaker panel
with eveything in the house turned off, then measure again with everything
turned on: as much load as you can get, waffle irons space heaters all the
lights etc. I believe there is a go/no-go criterion for the maximum drop you
should measure, but I don't know what it is (NEC should say). If you want to
be a bit more detailed, calculate the actual high load you are placing,
measure the drop, and then multiply the drop by the ratio of the main
breaker size to the load. For example if you calculate you are drawing 50
amps and the drop is 6 volts, and you have a 200 amp main breaker, it's
reasonable to assume you'd get a 24 volt drop at 200 amps draw, which I
think is clearly too much. One could argue that despite the fact that you
have a 200 amp breaker, the anticipated load would not be 200 amps therefore
the power company might thumb their nose at your calculations, but the
counter-argument (that the service to a 200 amp breaker should be sized for
200 amps) probably prevails in code. You should do your measurements on each
side of the split phase, understand the pattern of the bars behind the
breakers, and probably add and shed loads by flipping the breakers
themselves. If you're carefull in your calculations (or move your appliances
so that they're all on one side, then the other), you may find that one side
has a much higher drop/resistance than the other side, which would almost
certainly indicate a problem. Finally, you might try leaving the high load
connected for 30 minutes or so (each side) while checking the various
components for hot spots: and be prepared for an electrical fire anywhere
between your breaker box and the power co's transformer. Do these
experiments in the order presented, if the voltage drop in the first
experiment is significant don't try the second. My guess is, if you discover
excessive drop and report it, the power co won't charge to inspect: but if
they determine your feed is undersized and must be replaced they will
probably charge for that.

-Jeff

"Tom Haley" <haley-tom@comcast.net> wrote in message
news:Je6dna_8hvS8rHjYnZ2dnUVZ_rylnZ2d@comcast.com...
> Continuously.
> The service is 240v centertapped.
> Neutral is good and well grounded. Good 120V reference to each leg.
> Branch circuit is a rated 20A with 12 AWG copper conductors. It is a
> dedicated circuit with no other loads other than the washer.
> Circuit breaker is sized appropriately
> Total length of branch circuit conductors is less than 40 feet.
> The cycle of the flickering lights appears to coincide with the reversal
of
> the agitator (1-2 seconds)
> Connections at the panel and the receptacle are tight.
> I haven't measured the actual current draw of the motor. That may be
> worthwhile.
> <hrhofmann@att.net> wrote in message
> news:1172637146.206328.85920@k78g2000cwa.googlegroups.com...
> to
> machine
>
>
>

Jeff Miller

2007-04-12, 3:25 am

Oh by the way there is no filter per se that would help. If you placed a
huge ferro-resonanant transformer(s) ahead your other loads, that might
help, but that would be an absurd approach that really deosn't address what
could be a real problem. That having been said, it's not uncommon to use
ferro-resonant tranformers ahead of sensitive equipment to help isolate them
from voltage variations like you describe. FR transformers are sometimes
incorporated into UPS systems, especially in big ones. FR transformers are
sometimes built into medical and scientific equipment as well, especially
older gear. Newer, wide input range switching power supplies and solid-state
regulators have rendered them largely obsolete.

-Jeff
"Tom Haley" <haley-tom@comcast.net> wrote in message
news:Je6dna_8hvS8rHjYnZ2dnUVZ_rylnZ2d@comcast.com...
> Continuously.
> The service is 240v centertapped.
> Neutral is good and well grounded. Good 120V reference to each leg.
> Branch circuit is a rated 20A with 12 AWG copper conductors. It is a
> dedicated circuit with no other loads other than the washer.
> Circuit breaker is sized appropriately
> Total length of branch circuit conductors is less than 40 feet.
> The cycle of the flickering lights appears to coincide with the reversal
of
> the agitator (1-2 seconds)
> Connections at the panel and the receptacle are tight.
> I haven't measured the actual current draw of the motor. That may be
> worthwhile.
> <hrhofmann@att.net> wrote in message
> news:1172637146.206328.85920@k78g2000cwa.googlegroups.com...
> to
> machine
>
>
>

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