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Old 08-05-2010, 03:31 PM   #1
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A/C causes lights to "brown out"


We recently purchased a home built in 1968. The electrical system appears to be original, but the home inspector noted no deficiencies beyond a lack of AFCI circuit breakers and GFCI receptacles, as required by current code. He mentioned in informal discussion that the electrical service to the home is not at all oversized, meaning we wouldnít be able to add a pool, hot tub, or other major electrical user without some upgrading.

We havenít moved in yet, but after being in the home preparing to, we noticed that when the air conditioner kicks on, there is a noticeable diming of the lights in the house. Iím worried this might pose a risk and how it will affect my TV and computer .

Am I concerned over nothing? Is there something I can do to address the problem?

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Old 08-05-2010, 06:39 PM   #2
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A/C causes lights to "brown out"


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We recently purchased a home built in 1968. The electrical system appears to be original, but the home inspector noted no deficiencies beyond a lack of AFCI circuit breakers and GFCI receptacles, as required by current code. He mentioned in informal discussion that the electrical service to the home is not at all oversized, meaning we wouldnít be able to add a pool, hot tub, or other major electrical user without some upgrading.

We havenít moved in yet, but after being in the home preparing to, we noticed that when the air conditioner kicks on, there is a noticeable diming of the lights in the house. Iím worried this might pose a risk and how it will affect my TV and computer .

Am I concerned over nothing? Is there something I can do to address the problem?
So this home inspector has put a little fear into you. Did he do a load calculation? AFCI and GFCI were not required but that doesn't mean your electrical system is toast.
What major appliances are 240V? Stove, dryer, water heater, AC?
Look in your panel for the main disconnect and tell use the number printed on the handle - that will at least tell us your service size.
When the AC starts, it will draw extra current but after the compressor starts, the current requirements drop. We don't always notice that the lights went back to full brightness.

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Old 08-05-2010, 07:16 PM   #3
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A/C causes lights to "brown out"


Current code as in 1968? GCFI protected outlets in the Kitchen, Bathroom, Garage, basement maybe, but no need for breakers. As for ACFI, yes you could go with the bedroom outlets, I am betting if anything, that you have Aluminum wiring. It is called fear mongering, or the Chicken Little effect.

Does this inspector have any ties to local electricians, like one of the local builders in our town that not only does home inspections, but have other trades that they "sell", which creates a conflict of interest, but the city will not do anything, because this company donates huge sums of money to the local politicians.

As for the computer & other electronics, especially tv set, you should use good quality surge protectors. For the computer & tv, especially if a HD set, you should place both on battery back up with surge protectors built in.
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Old 08-05-2010, 07:42 PM   #4
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A/C causes lights to "brown out"


Quote:
Originally Posted by oleag00 View Post
We recently purchased a home built in 1968. The electrical system appears to be original, but the home inspector noted no deficiencies beyond a lack of AFCI circuit breakers and GFCI receptacles, as required by current code. He mentioned in informal discussion that the electrical service to the home is not at all oversized, meaning we wouldnít be able to add a pool, hot tub, or other major electrical user without some upgrading.

We havenít moved in yet, but after being in the home preparing to, we noticed that when the air conditioner kicks on, there is a noticeable diming of the lights in the house. Iím worried this might pose a risk and how it will affect my TV and computer .

Am I concerned over nothing? Is there something I can do to address the problem?

Stays dimmed ? Or lights dim then return to normal brightness? If it is just dimming then returning to normal ... this is very common due to current inrush when the compressor starts. It can be annoying and sometimes you can reduce or eliminate this dimming by using a hard start capacitor kit installed outside in your condensor/compressor unit. This will get the compressor started faster and the inrush doesn't last as long. Normally these kits are used for compressors that will not start on the existing capacitor due to several reasons but these kits also will make dimming of lights less objectionable in many cases.. Last I looked a 'hard start kit' was around 30$.
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Old 08-06-2010, 03:17 PM   #5
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A/C causes lights to "brown out"


It appears I failed to explain the situation adequately and caused some confusion with my post. The inspectorís findings didnít cause me to be concerned or I would have investigated them further before buying the home. Nor did he try to sell me anything or direct me to any 3rd parties to provide electrical service. He only mentioned that if we were to ever add more large energy using devices (i.e. pool, hot tub, etc.) we ďmightĒ need to upgrade the service size to accommodate the additions.

My biggest concern is that I donít want my TV or computer to lose enough power that it dims, loses its picture, or shuts off when the A/C engages. The dimming lights are an annoyance more than anything, but I would like to do something to improve the situation if possible.

I appreciate each of your comments, and below I have attempted to answer your questions.

Here are the 2 pages from his report describing the electrical systems.
Home Inspection - 11&12.pdf

a7ecorsair Ė
I spoke with the inspector. He did not do a load calculation. The main disconnect is labeled 100. He indicated that a home of this size would likely have 150 Amp service, if it were built today. The oven & stovetop (separate units), dryer, A/C, and heater are all on 240V.


gregzoll Ė
Current code as in, todayís code would require AFCIs and GFCIs . According to the inspector, we have copper wiring.

Weíre using a surge protector currently for the TV and computer. Iíll look into a better, higher rated one that provides battery back-up, also.


Stubbie Ė
The lights dim only momentarily, 1 to 2 seconds max, and then return to normal brightness. The home inspector also mentioned that a hard start kit might help the problem. Is that something I likely can install myself? Or is it better left to the pros?
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Old 08-06-2010, 03:21 PM   #6
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A/C causes lights to "brown out"


Correct me if I am wrong. That year it was common for 100amp installs instead of the 200amp because of the shortage of copper. Thus the draw maybe high for a 100amp causing a temporary dimming?

I may be way off base here and some of the more seasoned can attest if I am wrong or right.
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Old 08-06-2010, 09:17 PM   #7
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A/C causes lights to "brown out"


Sorry to say this, but this guy is an idiot that inspected the home. Find another inspector. Can you post the complete report Oleag00 if you mind. This is just gold. This is not by chance a Bank owned or HUD loan home is it?

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Old 08-06-2010, 09:22 PM   #8
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A/C causes lights to "brown out"


I would plug the TV and computer into a UPS. problem solved. The UPS will kick in to compensate during the brown out.

At my parent's house whenever I used the laser printer, my computer would reboot. Plugged the computer into a UPS and problem solved.
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Old 08-06-2010, 09:34 PM   #9
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A/C causes lights to "brown out"


There could be many issues causing this. One of my customer's lights dimmed when their neighbor's air conditioning turned on. They called me to see if their neighbor was stealing their power. It turned out to be too many houses on one transformer, the PoCo added another transformer and all was well.



oleag00, How far are you from the street? Some PoCo's use as small as #8 overhead feeders for older 60-100amp services. If it's a long run the voltage drop might be causing the dimming.
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Old 08-06-2010, 10:13 PM   #10
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A/C causes lights to "brown out"


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There could be many issues causing this. One of my customer's lights dimmed when their neighbor's air conditioning turned on. They called me to see if their neighbor was stealing their power. It turned out to be too many houses on one transformer, the PoCo added another transformer and all was well.



oleag00, How far are you from the street? Some PoCo's use as small as #8 overhead feeders for older 60-100amp services. If it's a long run the voltage drop might be causing the dimming.
Excellent point.
Don't always think the PoCo has everything right.
Just wondering, what size AC do you have and what size breaker serves it? If you want to do some testing, turn off as much stuff as possible and then just one lamp. Cycle the AC. If the lamp as noticeable dimming you may want to check into this further. Does the dimming seem more noticeable during times when your neighbors would have more load on the system?

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Old 08-07-2010, 01:35 AM   #11
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A/C causes lights to "brown out"


gregzoll Ė
Iím curious. What leads you to conclude the home inspector is an idiot? It was not a bank owned or HUD home. It's a full brick, 2,600 sqft, ranch style home built in 1968. It does suffer from some deferred maintenance type issues the elderly sellers didn't attend to properly. At this point I fail to see what good another inspector does me.


Red Squirrel Ė
Thanks for the UPS idea. Iíll look into that.


Proby Ė
The power here comes from the back of my lot, and my breaker box is likely 75 feet or less from the power pole. Iíll try to determine the actual distance to the transformer tomorrow, er today. Man itís getting late already.


a7ecorsair Ė
The lights only dim in conjunction with my A/C starting. They've never dimmed any other time. Iíve likely spent 50-60 hours over there in the past 2 weeks, but mostly evenings and weekends. I would assume this would be prime time for my neighbors to be using power also. It has been in the high 90s, low 100s here recently. Iíll check the A/C and itís breaker size tomorrow.


Thanks for all the help everyone.
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Old 08-07-2010, 02:58 AM   #12
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A/C causes lights to "brown out"


You don't need another home inspector, wouldn't do any good anyway. YOUR HOME IS TYPICAL of many homes of that era. I wouldn't worry about the dimming it is not going to harm anything. Do the things that were constructively suggested by the other posters for peace of mind. Enjoy your new home.
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Old 08-07-2010, 10:35 AM   #13
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A/C causes lights to "brown out"


If you think the dimming is excessive, then add the hard start kit as the inspector and stubbie reccomended.

You can always add the gfci's later if you feel that you need to.
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Old 08-07-2010, 12:28 PM   #14
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A/C causes lights to "brown out"


As a side note, the Texas rules for home inspectors require them to report the lack of AFCI protection, even if the technology did not exist when the home was built.
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Old 08-07-2010, 12:46 PM   #15
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A/C causes lights to "brown out"


I have a UPS on my TV & computers
Cheap protection
My last house had lots of short power outages...sometime less then a minute

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