House lights dim with loading inside new house

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  #1  
Old 01-13-12, 02:12 AM
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Location: Hong Kong
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House lights dim with loading inside new house

I'm in Hong Kong (but native USA) and have 240/50 3 phase throughout the house. The house I'm in is 3 story / units, brand new.

Many lights are compact flourescent, but the ones that are incan are flickering quite a bit when there are loads applied, both in my unit, and (likely) from the two units above.

So I put a meter on one of the outlets, and I get between 200-220v depending on the loading. Turning on a water heater, for instance, will lower the voltage about 3-4 volts. Turning on a 2000w space heater, will lower it by another 2-3 volts. And so on....I put the meter both "line -to- return" and "line to ground" and get the same voltage. "Return to ground" gives zero.

Is the voltage supposed to drop like this? And is my unit supposed to be affected by the other units/resident's activities? (I can see the lights dim/flicker with any loads)

I've been looking into this, and there seems to be two main possibilities: inside wiring issue, like loose wire somewhere, or outside issue, like power company problem. Seems if the issue is related to loads, its probably inside, right?

Thanks for your insight!
Jason
 
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  #2  
Old 01-13-12, 07:36 PM
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Location: Juneau, Alaska
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Welcome to the forum. When I was working in Indonesia, this is a common problem on mostly houses there. The reason behind which maybe applicable in your situation is the amount of electrical power allowed by the power company for each individual houses. In my case, the maximum connected to my place was only 1500W at 380v/3ph/50Hz and everytime we use a bigger load, like airconditioning unit, the light flickers or the main breaker trips. It is something that the power company only allocate this amount of power to each houses. Perhaps, you may inquire or check what is the size of your main breaker to your house. There is also a possiblity of loose electrical connection somewhere. From the meter readings you posted I think your power supply is also 380v either single phase or 3-phase with neutral, and what you read for 220V is the line to neutral voltage which is the common household voltage in Asia. In my experience in Indonesia, when the voltage drop below 200v, even the compact fluorescent bulbs flicker too or even will not light. Hope this may be of help.
tinoM
 
  #3  
Old 01-14-12, 12:22 AM
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So, is it normal for loads, big or small, to lower the voltage in the house? Even in the USA?

I'll check about the the total coming in to the breaker, but we have pretty normal power here in Hong Kong. I would say on par with USA at the least.
 
  #4  
Old 01-14-12, 05:52 AM
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Location: USA
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I would say that a 1% drop in voltage for a 2kw space heater is better wiring performance than most homes.
; in fact, is very good.
 
  #5  
Old 01-14-12, 10:37 PM
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Location: Juneau, Alaska
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In my experience on household loads where you plug in something on the same circuit especially motors, you will notice a slight flicker or drop in voltage but not 10%. I would suggest if you have access to the your main electrical panel try to check if there is sign of a loose connection on the main terminals or lugs. Have you checked your neighbor if they are experiencing the same as in your place? Is the main panel supplying power to all the houses(units) above yours? I have come across a problem here about flickering lights especially when someone used a big load like range/oven and upon checking the main electrical panel I found out that one of the hot leg is loose and showing sign of burned insulation. I just tightened the said terminal and the flickering was gone. Hope this may be of help. Good luck.
tinoM
 
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