Brand New Construction Lights Dim in a few places with Vacuum load

[juant1971]

I just moved in to a brand new home, before moving in I decided to clean the floor tiles. Noticed that the master bath lights dim pretty bad when I turned on the vacuum which was plugged in the master bedroom. There is a overhead shower light, 2 exhaust fans, toilet light, and 2 light fixtures which hold 3 LED light bulbs each at 9 watts, this in addition to 2 closet fluorescent light fixtures all the receptacles and the overhead ceiling fan in my bedroom and all are on the same breaker. Just using the light fixtures and nothing else on the lights dim pretty bad is this normal or can there be something I need to investigate further.

This issue came up as soon as I turned on the vacuum with just the bathroom lights on, no other load was present besides the vacuum cleaner. I do understand that there is inrush current taking place, but is there anything I can get checked out or is this something absolutely normal to expect from this situation. This is all on a 15 GFCI/AFCI dual breaker in the panel using the normal 14 AWG wire. I don't really get how this type of install can make it thru inspections as this does not look like something very safe in my opinion. This is also happening in my hall bath and second and third bedroom which are also connected in to a 15 AMP dual breaker just not as bad as my master bathroom.

 

[GoldDigger]

It probably is not "normal". Before deciding whether to tolerate it or get it repaired, you or another licensed electrician if you are not comfortable with the troubleshooting process, need to measure the actual voltage drop at the vacuum, and at the panel end of the branch circuits. It is possible that what you see is the result of a bad connection on the hot side of the circuit, possibly before the panel bus, or else a problem with the neutral conductor.
Your profile is not clear on whether you work as a licensed electrician or not, so we may not actually be able, under the forum rules, to help you on this issue.

 

[juant1971]

It probably is not "normal". Before deciding whether to tolerate it or get it repaired, you or another licensed electrician if you are not comfortable with the troubleshooting process, need to measure the actual voltage drop at the vacuum, and at the panel end of the branch circuits. It is possible that what you see is the result of a bad connection on the hot side of the circuit, possibly before the panel bus, or else a problem with the neutral conductor.
Your profile is not clear on whether you work as a licensed electrician or not, so we may not actually be able, under the forum rules, to help you on this issue.

Thanks for the answer I am a licensed electrician and work on commercial temporary power distribution as my main occupation. I have actually metered my main panel to ensure my load is balanced and have checked all the connections in my panel and found some wiring to be a little loose. Tightened up the connections but I am still dealing with the same issue at the moment. The utility company has also came out to ensure their end is okay and found no issue to report. I do have the electrical contractor coming out to check out this issue for a second time, the first time they came out they plugged test the outlets saw the issue and said he would change out the breaker. In his professional opinion this is totally normal and it happens just about every where, which raised a red flag in my mind since my last house which is 12 years older I never dealt with such issue. I understand exactly what a loose connection can do first hand especially since I work with 3/0 power in my field. I also would not tolerate such issue happening in equipment we power up in my industry. I will test out the voltage drop at the vacuum and at the panel end of the branch circuits. I simply would like to cover my basis and then decide if this is something really worrying about. However I don't understand how the NEC would accept for such installation if this were to be diagnosed as a normal and safe occurrence. Thanks for your help on this question.

 

[GoldDigger]

FWIW, many POCOs will send someone out for the initial investigation of a complaint like yours without any way of generating a high current test load. If the POCO rep did not connect a test load (often called a Beast of Burden), then I would not say that the POCO side has truly been ruled out.
As I alluded to but without details, you can measure the voltage (and therefore the voltage drop) at different locations along the current path, from a receptacle on the circuit that dims and the one the vacuum is connected to, back to the breaker terminals, the breaker bus and the line connections to the main breaker. Knowing where the voltage drop is happening is critical to identifying the cause.

 

[gar]

200121-2347 EST

juant1971:

You have a problem.

On one of my circuits, #12 copper, and an Oreck sweeper I saw an 0.8 V change at the outlet where the sweeper was plugged into. Next I put a 15 W incandescent on the output. Very slight flicker.

A 2 V change is needed for a more noticeable flicker,

Get a DVM that resolves 0.1 V when on a 200 V scale, and a 1500 W space heater, about a 10 A load at 120 V;

Remove the cover from the main panel. Make input voltage measurements directly on the incoming wires. Line to line, each line to neutral, neutral to ground rod, and neutral to EGC.

Connect the 1500 W heater somewhere. With the heater load repeat the above measurements and report your results.

.

 

[growler]

Noticed that the master bath lights dim pretty bad when I turned on the vacuum which was plugged in the master bedroom. I don't really get how this type of install can make it thru inspections as this does not look like something very safe in my opinion. This is also happening in my hall bath and second and third bedroom which are also connected in to a 15 AMP dual breaker just not as bad as my master bathroom.

An electrical inspection is mostly visual, the inspector may use a plug in tester to check for correct polarity and that grounds are connected but other than that he just turns on a few lights. If an electrical inspector noticed lights dimming I'm pretty sure this would be a red flag. They just don't carry around vacuum cleaners.

 

[growler]

The last time I had this issue in a new house it was more localized, the lights were dimming in an upstairs bathroom. when I opened the switch box I didn't like the way they had done their connections so I redid all taps and changed out the switches and also the lamps.

Your problem sounds like it may be on the POCO side of things or even in the meter box or main breaker. Over the years I have found loose connections all over the place even on new construction. All it takes is one screw or lug that didn't get properly tightened/torqued.

 

[kwired]

Exactly why I learned long ago to avoid putting lights and receptacles on same circuit - in particular on 15 amp ciruits with 14 AWG conductors.

Voltage drop is a common problem when you have a heavy load, and LED lights seem to have even more dramatic effects than incandescent typically did in these situations. Probably about 30 years ago I still recall a customer having issues with satellite TV receiver as soon as the vacuum got turned on - voltage drop, 14 AWG conductors, mobile home with possible shoddy devices/connections was what we determined to be the cause.

 

[juant1971]

200121-2347 EST

juant1971:

You have a problem.

On one of my circuits, #12 copper, and an Oreck sweeper I saw an 0.8 V change at the outlet where the sweeper was plugged into. Next I put a 15 W incandescent on the output. Very slight flicker.

A 2 V change is needed for a more noticeable flicker,

Get a DVM that resolves 0.1 V when on a 200 V scale, and a 1500 W space heater, about a 10 A load at 120 V;

Remove the cover from the main panel. Make input voltage measurements directly on the incoming wires. Line to line, each line to neutral, neutral to ground rod, and neutral to EGC.

Connect the 1500 W heater somewhere. With the heater load repeat the above measurements and report your results.

.

Thanks for the answer and input I will be doing this over the weekend and report the results back.

 

[juant1971]

Exactly why I learned long ago to avoid putting lights and receptacles on same circuit - in particular on 15 amp ciruits with 14 AWG conductors.

Voltage drop is a common problem when you have a heavy load, and LED lights seem to have even more dramatic effects than incandescent typically did in these situations. Probably about 30 years ago I still recall a customer having issues with satellite TV receiver as soon as the vacuum got turned on - voltage drop, 14 AWG conductors, mobile home with possible shoddy devices/connections was what we determined to be the cause.

Very good point and my thoughts exactly why do it? we know why to save money and build houses cheaper at a higher cost to the consumer. But I will fight this one because I just don't think this should meet code period.

 

[juant1971]

An electrical inspection is mostly visual, the inspector may use a plug in tester to check for correct polarity and that grounds are connected but other than that he just turns on a few lights. If an electrical inspector noticed lights dimming I'm pretty sure this would be a red flag. They just don't carry around vacuum cleaners.

I agree well maybe the NEC will make them do a load test on circuits and this would assist in getting rid of this particular issue. Perhaps they will make them carry some sort of motor load to test the circuits.

 

[hbiss]

Unfortunately the NEC doesn't address voltage drop so no inspector is going to look at it. This would be a quality control or design issue and falls on the installing EC to do the testing prior to turning the project over to the owner. There too, unfortunately nobody that I know of does that unless it's written into the contract. So it's up to the owner to report such problems just as you are doing.

-Hal

 

[juant1971]

Unfortunately the NEC doesn't address voltage drop so no inspector is going to look at it. This would be a quality control or design issue and falls on the installing EC to do the testing prior to turning the project over to the owner. There too, unfortunately nobody that I know of does that unless it's written into the contract. So it's up to the owner to report such problems just as you are doing.

-Hal

I completely understand it's pretty sad as inspectors now days just walk in and walk right out. I am pretty sure that if a few fires were to take place something would be done to reinforce the code and come up with more stringing restrictions. You are seriously talking about lives here not just a property. In fact most people who are not in the field working on electricity may not even report it and if they do they are told by the EC what I was told. This is normal and there isn't anything you need to worry about, then they send a so called electrician who sees the problem and says oh this is normal in fact it happens in my house when I run the microwave. I appreciate your comment and will keep you all posted after next tuesday when the EC comes by and hopefully agrees that there is an underlying issue. Thanks

 

[Sierrasparky]

I completely understand it's pretty sad as inspectors now days just walk in and walk right out. I am pretty sure that if a few fires were to take place something would be done to reinforce the code and come up with more stringent............

That is why the NEC pushed ARC fault devices . To detect those loose connections.

 

[ptonsparky]

That is why the NEC pushed ARC fault devices . To detect those loose connections.

Thats what we all thought anyway.

 

[Little Bill]

That is why the NEC pushed ARC fault devices . To detect those loose connections.

I hope you are kidding! AFCIs do not detect loose connections. Hence the "glowing" connection that they NEVER detect!

 

[hbiss]

I completely understand it's pretty sad as inspectors now days just walk in and walk right out. I am pretty sure that if a few fires were to take place something would be done to reinforce the code and come up with more stringing restrictions. You are seriously talking about lives here not just a property. In fact most people who are not in the field working on electricity may not even report it and if they do they are told by the EC what I was told. This is normal and there isn't anything you need to worry about, then they send a so called electrician who sees the problem and says oh this is normal in fact it happens in my house when I run the microwave. I appreciate your comment and will keep you all posted after next tuesday when the EC comes by and hopefully agrees that there is an underlying issue. Thanks

Fact is it may be normal. Keep in mind that peoples perception of dimming and flickering varies. But only testing will determine if there is a problem.

As for fires, I think you are over reacting. Rarely are there problems in new homes that go beyond the device boxes. If a home is going to burn down it's because of DIY electrical work or the people who live there doing something they shouldn't be doing. That's not something that Code changes are going to fix.

-Hal

 

[kwired]

Very good point and my thoughts exactly why do it? we know why to save money and build houses cheaper at a higher cost to the consumer. But I will fight this one because I just don't think this should meet code period.

I'm not convinced that common practices of wiring each bedroom with an individual 15 amp circuit makes that significant of cost difference. I usually run 12 AWG to nearly all receptacle outlets and use 14 AWG for nearly all lighting circuits. With that practice, a cluster of 4 bedrooms might only have one 20 amp circuit and one 15 amp circuit - plus the 15 amp circuit might do some other lighting like in an adjacent bathroom or hallway, where those guys doing one 15 amp circuit per room already have additional cable in their home runs, more expensive AFCI breakers than I have, plus more light dimming when a heavier load plugged into the receptacles is turned on.

 

[growler]

Thanks for the answer I am a licensed electrician. I will test out the voltage drop at the vacuum and at the panel end of the branch circuits. However I don't understand how the NEC would accept for such installation if this were to be diagnosed as a normal and safe occurrence.

The thing to remember is that the NEC is a minimum set of safety standards and not a design manual.
The next thing to remember is that the guys that rope houses are often not your more experienced electricians.

To test for voltage drop you need to know the voltage at the panel with applied load and you also need to know the load amount. Then check for voltage at the receptacle with the vacuum still running. The next thing you need is a pretty good estimate of the total length of conductors from the panel to the receptacle. Once you know the length of the conductor, the load and the voltage drop you should be able to calculate what the voltage drop should be and compare that to the actual voltage drop. If the calculation and the measured voltage drop are the same then their are no loose connections. If the actual voltage drop is more than what it should be there is very likely a bad connection that may cause problems.

 

[Sierrasparky]

I hope you are kidding! AFCIs do not detect loose connections. Hence the "glowing" connection that they NEVER detect!

I have fixed AFCI issue and it was a loose connection from a loose not melted wire nut at a light fixture the customer replaced recently