Lights flicker when heater or freezer motor turn on

[erowland]

Hi - I'm new to the forum and I've viewed previous posts on this topic but...

Background - My home is being built in Culpeper VA. Close date is Feb. 8. Electrical is complete. I've noticed that when the heater or freezer motor starts the lights dim momentarily. Mind you...there is "nothing" in the house (new build) except the appliances. Service from the street is 2 x 200A (each having it's own distribution panel).

When I brought this to the builders attention, and then when I spoke directly to the Kellog electrician who did my home they both said: "This is going to happen. You'll get use to it!" The electrician went on to say it's happening because all of the neutral wires are common (ganged together I guess). It doesn't sound right to me!!!

I'm 42. Lived lots of places. Aside from a storm causing power fluctuations I've never run into this and I'm sure as heck not going to "get use to it" ....unless, I guess, it is a common problem that I need to get use to.

Please, any advice would be helpful.

Thanks,

Ed R.

(Moderator?s Note: Edited to remove email address. If you wish to send an email message to this person, then first send a Private Message via this Forum, and ask for the email address.)

 

[bphgravity]

Re: Lights flicker when heater or freezer motor turn on

I only have one comment, this is going to happen. You'll get use to it. In all reality, you probably don't have a problem. You probably have high effeciency equipment. This creates VD on start-up.

 

[hbiss]

Re: Lights flicker when heater or freezer motor turn on

I don't agree and this question belongs in another forum, not here in the LV forum.

This guy has a 400 amp service, that's big wire. How big is the heater or freezer motor? Where is the voltage drop?

By the way your EC is full of it when he says it's because "all the neutrals are common". Does this effect all the lights in the house or just some?

-Hal

 

[peter d]

Re: Lights flicker when heater or freezer motor turn on

This is perfectly normal. I have the same "problem" in my house when the AC units start of the dryer starts. There is no electrical issue whatsoever.

 

[Ken9876]

Re: Lights flicker when heater or freezer motor turn on

It may be big wire, but what size wire did it connect to at the power company side. I find that in my area there are long runs with transformers few and far between. And an increased load over the years with out any up grades on the power company side.

 

[hbiss]

Re: Lights flicker when heater or freezer motor turn on

Right. The problem most likely is on the utility side and I have had success getting them to upsize their drop if the customer complains enough. A slight flicker or dimming is tolerable, more than that I would complain.

On my own house I even got them to do a midspan to get it closer to the transformer.

-Hal

[ January 19, 2006, 12:39 PM: Message edited by: hbiss ]

 

[rrr_usty]

I had a customer that had the same kind of problem, I had the utlitity do a load test and found a faulty neutral on their end. Even though it is a new home you can have the neutrals checked to make sure they are tight.

 

[charlie b]

Re: Lights flicker when heater or freezer motor turn on

I don't agree and this question belongs in another forum, not here in the LV forum.

You're probably right, and I started to move it. But I couldn't figure out which forum would better fit the question. So I'll leave it here for now. :wink:

 

[scott thompson]

A couple questions to the original poster:

1. Would the Lighting with the transient sag (Dimming when the Motor Loads are started ) happen to be Incandescent Lamps - such as "Basic" screwshell type Lamps and Quartz-Halogen Lamps?
   
2. Is the Utility Power Company's Transformer located in front of either your House, or one of the neighbors' Houses directly to the left or right side of yours?
   
3. How long is the duration of sag / flicker?
   
4. What is the intensity of sag / flicker?
   
5. Do other loads (cooking appliances, Disposal, etc.) cause Lighting flicker affects?

Question #1 addresses the most obvious scenario regarding flicker factors: the visual awareness of how Voltage levels will effect Incandescent Lamps, and be observed drammatically by the Human Eye.

The Increase/Descrease of output light levels according to the Voltage impressed on the Incandescent Lamp, are in a Linear Fashion - as are the Electrical Values involved with the Lamp when Voltage levels rise and fall.

An increase in Voltage by 5 or even 10 Volts results in an increased Current drawn from the system, an increased amount of True Power (Wattage) drawn from the system, and with the increased draw of True Power, comes an increased light output level.
If the system Voltage at the Lamp DECREASES, the exact opposite takes place: The Lamp draws less Current from the power system, which is the result of a lower level of True Power drawn from the system ("E" dropped, so "I" also drops, which resulted from a drop in "P" because the "E" dropped in the first place..corn fusing isn't it???).
Lower Wattage drawn from the system by the Lamp results in a lower output light level.

What I am getting at in Question #1 is that Humans observe the Linear reactions associated with Voltage Levels and Incandescent type Lighting very drammatically, whereas the same effects occur with Discharge type Lighting sources (Fluorescent, Neon, H.I.D. and even the CRT of a Television Set) go very un noticed - even though these devices still react to Voltage fluctuations.

On this note, do any Fluorescent Lamps react oddly at the same time of the flicker?

The reason you are seeing this Flicker Effect scenario when those appliances first startup, is due to the very large Inrush Current they are drawing during the start cycle.
Compressor type Motor loads have a heavy static load when they are at rest, so the initial starting process of these Motor loads results in a very heavy load current off the system - and this causes a drop in system voltage during the scenario.
As the Motor begins to increase spee, the load current of starting begins to taper down - with a corresponding increase in system voltage at the same time. When the Motor has achieved full operating speed and is running stable for a few seconds, the entire power system returns to a "steady state" - like it was prior to the Motor start.

Question #2 is to address the distance between the effected Lighting Fixtures, and the power system''s source - that being the Utility Transformer.
Overall distance will have a bearing on how drammatic Incandescent Lamps will react to voltage variations (flicker).

Question #3 is to address where Motor Locked Rotor Ampere draw effects the Lamps, and where the effects are a combination of terminations + Motor starting.
I will not give duration examples right now, as I would like to hear your answer first before addressing time / intensity values.

Question #4 is in the same respect to Question #3.

Question #5 is directed to the same lighting being effected by any other loads' usage - either at start, full usage, or end of use.

I'll check back later for replies.

Scott35

 

[scott thompson]

***BUMP!!!***




Scott

 

[unimo]

Lights flicker when heater or freezer

Lights flicker when heater or freezer

I do troubleshooting every day, and this is definitely not a normal situation. The other answers may be correct if all the wiring in the
house is done right, that it is a problem with the utility company,
but it's more likely the problem is in the house wiring. Unfortunately, something like this really has to be diagnosed in person as there are too many variables to do it over the net.
What leads me to believe it's not the utility company is the problem is caused by heater or freezer motors. These are really small motors for such a large service. You might expect something like this rarely from a washing machine, but not a freezer.
The first thing I would check is the neutral bonding to ground, and make sure it is the proper size and connections are tight. if they left it out it would cause this problem. Then check every connection in your panel, especially neutrals and feeders and grounding electrode conductor. Make sure grounding electrode clamp is tight and the connection to it.
You can determine if it is a utility company problem by shutting every breaker off in the house except an outlet right near the panel. Take a digital reading of the voltage between the feeders and neutral. Plug an electric heater in the outlet. Turn it on full and take another voltage reading. If the voltage is more than one volt lower when the heater is turned on, it's probably a power company problem. Try it a few times and at different outlets because voltage can vary over time.
Beyond that you'd have to go through every box in the house and check connections unless you are good at tracing.

 

[don_resqcapt19]

unimo,

The first thing I would check is the neutral bonding to ground, and make sure it is the proper size and connections are tight. if they left it out it would cause this problem.

How could the bonding or lack there of cause this problem????
Don

 

[unimo]

unimo,

The first thing I would check is the neutral bonding to ground, and make sure it is the proper size and connections are tight. if they left it out it would cause this problem.

How could the bonding or lack there of cause this problem????
Don

i'm not sure of the reason; maybe one of the engineers could answer this.
But my primary job is troubleshooting, and I know it causes the problem.
I had a house where every light in the house pulsated with the washing machine motor! As soon as I bonded neutral to ground it quit.
All I know is the bond sort of anchors the transformer voltage. you know how voltage goes down when your load goes up. If the bond is absent, put an analog voltmeter on your feeder to neutral, and the voltage reading will go crazy and not sit still for a minute.

 

[don_resqcapt19]

unimo,

But my primary job is troubleshooting, and I know it causes the problem.

I'm sorry but in no way is that the solution to the problem. Did the building where you did this have a metal underground water pipe?

If the bond is absent, put an analog voltmeter on your feeder to neutral, and the voltage reading will go crazy and not sit still for a minute.

The equipment does not care about the voltage to ground, only the voltage between the circuit conductors.
Don

 

[coulter]

...but in no way is that the solution to the problem. ...

Don - I think you are absolutely right. As you suggested, the equipment grounding conductors (bonding) is now carrying the neutral current.

carl