Flickering Lights

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gregsparky1

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I've been asked this question dozens of times and never feel confident with my answer. Customer asks why the lights flicker or slightly dim when the refrigerator or furnace comes on. I usually tell them it's a common occurance and is not a cause for concern unless the lights practically flicker off and on. Does anyone have a different "line" they tell their customers?
 
Could be many things.Under sized service,too many homes on same neutral,neutral wire going bad,Multi wire branch circuit,Frig itself having hard time starting.Some are serious problems some not.
 
The links from the website seem to be acting strange, go here for the whole story -

http://www.mikeholt.com/mojonewsarchive/All-HTML/HTML/Lights-Flicker-(Dim)-When-AC-Starts~19991007.php
 
Tell them it is due to Voltage Drop when the appliances or motors are starting (and maybe even running) and as you say is nothing to be concerned with unless it is extreme.

I try to be as concise as possible with out being insulting when explaining things to laymen.

Roger
 
our utility co "PG&E" is notorious for running well over what we would concider exceptalble loading on xfmrs and service drops. Maybe the problem is occuring before it even gets to the house. Example I ran a 4/0 cu service riser to a 200amp meter main all branch circuits in#12 short runs. lights dimmed when furnace or refer came on.Look at the street and the nearest utility xfmr not even in sight,all the houses on the block have the same problem. Makes us look bad when we go to extra steps to do a good job and it is out of our hands to fix. Utility co just gives you the run around about it.I have seen this in many homes neighbor uses a skillsaw and lights dimm two houses down.
 
Doesn`t matter what you install if the poco has inadequate supply then you can over size everything and still have complaints.
 
allenwayne said:
Doesn`t matter what you install if the poco has inadequate supply then you can over size everything and still have complaints.
Click to expand...


I agree, the problem is you all ways find out after the fact that the poco has run to small a line.....Value engineering......is what they call it.
 
I always like when a contractor will sell a service change to try to fix dimming lights. Doesn't do you much good if everything is still on the same circuit.

We have the same problem with SCE here in Southern Calif. they will design to less than 70% of the load because they say that not everyone will have everything on at the same time. Then you get to the older neighbor hoods and people have started adding AC and pools and room additions and everyone is upgrading to 200 amp services and SCE is still powering the neighborhood at 70% of 100 amps.

My neighborhood was so old that my lights dimmed when my neighbors AC came on.
 
Voltage drop is what is causing your lights to flicker, when a motor or air conditioner starts up, they draw about 3 times the starting currant for a period of time till the motor gets up to speed. The reason this shows up on lights is that a 1 percent drop in voltage causes a 3 percent drop in light output.
 
I think it's all a matter of the terms we use. In this case, precision is essential.

Flickering = very bad, more than likely a loose connection

Momentary dimming = not bad, as mentioned is due to motor loads
 
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