Thread: Odd problem, New construction, one side weak?

This one has lots of people baffled...

New Construction, 12 month walk-through...

Client complained when the washer spins the lights in certain rooms flicker in time with the washer, also the disposal makes the same lights flicker, and so on...

Turns out, everything on ONE SIDE of the Panel has issues. Bulbs burn out fast, High loads (Washing machine, disposal, etc make everything else on that side blink.

That side of the panel is about ~4v weaker than the other side.
Everything on that side of the panel shows a MUCH higher voltage drop under load than the other side.

I used my suretest in every room, and got the following numbers...

Laundry (simplex) 10.3% at 20A
Dining room 9 % at 20A
Family Room 4.4% at 20A
Den 5.8% at 20A
Living Room 6.2 % at 20A
Kitchen #1 6.3% at 20A
Kitchen #2 6.1 % at 20A
Front Bed 17.6% at 20A 13.2% at 15A
2nd hall bath 8.8% at 15A
Mbed 18% at 20A 13.8% at 15A
Toy bedrm 12.4% at 20A 9.3% at 15A
rt fnt Bed 6.2% at 20A 4.7% at 15A

I realized about 1/2 way through the house that some of the 15A circuit WOULD have higher drops at 20A, but I continued and tested EVERYTHING at 20A for consistency, but got many of the 15A circuits at 15A as well.

Some circuits were ~4-6% drop, others were ~14% drop, -Depending on which side of the Panel they were on-. The Voltage at the Panel was ~117 on the left and ~121 on the right. Everything was tight and Cool (I used my thermal Imager on the Panel, no hot spots other than the stack of AFCI"s (image below for those who don't think a stack of AFCI's don't get rather warm...))



Other than "Have Evaluated by licensed Master Electrician..." dose anyone have any idea where to point them? I was thinking that is could be in the meter socket or beyond...A higher resistance somewhere could be doing it... they are very near the transformer...(at end of driveway) don't know if they can have the local power company do a test of the feeds...

With only a Suretest and a MultiMeter and no helper I couldn't pull a load and watch the feed at the panel at same time (I doubt the Suretest loads long enough for the multi-meter to see it anyway)

The Client was happy with what I did, documented, and looked at...but I said I would post a message in a few places and see if anyone had some ideas...(Jerry ?)

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Since the circuits alternate on each side of the panel the fact that one side seems to have all the problems in probably a coincidence. Those VD numbers are not good but in general VD is not a code issue but a design issue so that may affect how you report it.

How did you measure the 4 volt difference between the two sides? Do you do so with all of the branch circuit breakers in the off position?

Originally Posted by Bob Sisson

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Client complained when the washer spins the lights in certain rooms flicker in time with the washer, also the disposal makes the same lights flicker, and so on...


Other than "Have Evaluated by licensed Master Electrician..." dose anyone have any idea where to point them? anyone had some ideas..)

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Call the Locale Utilities and tell them the lights flicker when other appliances are under load. They will Check the connections coming in.

Sounds like the Neutral is loose. Tight at the Service Panel ? ( is this under ground service? )
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Loose or bad neutral connection, or simply a bad neutral.

Power company needs check the neutral connections in the meter and at the transformer. If that checks out good, then have an electrical contractor check the neutral and its connection in the service equipment.

Your client is fortunate that there is *ONLY* a 4 volt difference, usually when there is a bad neutral the difference is more like 70 volts on one phase leg and 170 volts on the other phase leg.

The difference in voltage is due to differences in load on the two phase legs and the fact that the neutral is no longer keeping the center point of the 120 volt / 120 volt at ground. There will always still be 240 volts across the two phase legs, but let's say that you have a toaster on on phase leg and a 60 watt lamp on the other phase leg - the voltage across the two loads placed in series on the 240 volt circuit will be dramatic.

The grounded neutral keeps the voltage at 120 volts and 120 volts regardless of the loads on the phase legs ... lose the neutral ground connection and you now have the loads playing off each other with 240 volts across the two loads in series.

To make it even more difficult: loose or poor ground connection of the neutral ... now the results will vary all over depending not only on the two loads but also on 'how bad'/'how good' the neutral ground connection is at that specific moment in time ... that will really drive you crazy ... until you realize 'Oh, yeah, bad neutral, forget the differences - correct the bad neutral to ground connection or the bad neutral and the problem goes away.

Originally Posted by Billy Stephens

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Call the Locale Utilities and tell them the lights flicker when other appliances are under load. They will Check the connections coming in.

Sounds like the Neutral is loose. Tight at the Service Panel ? ( is this under ground service? )
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Sorry Charlie ( uh Jerry ) .
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Originally Posted by Billy Stephens

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Sorry Charlie ( uh Jerry ) .
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Billy,

I saw your post after I posted, I just put more thought and explanation into my post so it took me longer to type.

In the end, though, we said the same thing: It's the neutral.

(I just explained why. )

Originally Posted by Jerry Peck

Billy,

I saw your post after I posted, I just put more thought and explanation into my post so it took me longer to type.

In the end, though, we said the same thing: It's the neutral.

(I just explained why. )

,
Oh Yeah it be All That Thinking !

Bob,

Get the home owner to call the Power Company and get Real Animated about the Lights are going Crazy , Da House is gonna burn down whit my Babies in it Bla, Bla,

The Service Truck will be Sitting there within 45 minutes. ( other wise you get put on the list week from Next Tuesday.

I measured the voltage using my mufti-meter at the top incoming service entrance lugs in the panel to the ground buss bars. The difference was low and it was bouncing around a lot. I looked at all the connections in the Panel with my thermal camera and all were cool with no visible corrosion.

All of the breakers were on...

I was there to do a 12-month walk-through and this was just part of the overall inspection.

I realized that with the Suretest and my thermal imager, I had more tech than MOST of the electricians I have seen. Only the really good ones carry Mega-ohm meters, ground testers, recording survey meters and the like...

The source of trouble is possibly ahead of the main panel. Years ago, I had a similar situation that turned out to be a bad connection out on the utility pole. They should get the service drop checked, is what we're saying.

We had a problem in one of our condos and I had the Utility Co. come out. They had a problem in the transformer.

Originally Posted by John Kogel

The source of trouble is possibly ahead of the main panel.

Originally Posted by Jack Feldmann

They had a problem in the transformer.

That's why I recommended calling the power company first, then the electrical contractor - because the problem is likely at the transformer, the service entrance conductors connection to the transformer, or even the service entrance conductors themselves. If not those items, the problem would then likely be at the service equipment panel.

It is not unusual to have those power company problems, especially on either a brand new house (I've found it many times on brand new houses) or on a older home (especially over 20 years with direct burial underground service lateral - this happened to our house in South Florida, the power company found that the neutral had almost completely deteriorated to powder for about 6 inches of so).

Client called the Utility...

Says they measured lots of things, and in the process things -seemed- to have gotten better... Sounds like they tightened a bolt somewhere... Stay tuned...

Sometimes the problem is with a neighbor supplied off the same tapped 1~ step down tsf.