I have a residential house wired in rx single phase, which has a intermitten blicking of lights, they do not go off they just dime.
Things I have done or checked.
Power co replaced neutral splice at weatherhead.
Tightened every connection in panel.
Checked ground wire at street side of water meter.
Pulled meter and check connections, which were fine.

The dimming seems to happen on every circuit, not just one.

My next step is to call power co. again to check meter,and 230volt lines.
Any ideas out there?
Mike

Do any lights get brighter at the same time as other lights get dimmer? The neutral at the power company's transformer could be bad, and no amount of solid ground connections in the customer's house will help that. The power company would have to fix that.

Do the lights in neighbors' house (fed by the same transformer) also dim, and at the same time? In addition to the above possible bad neutral at the power company transformer, could be a bad connection on the primary side of the power company transformer, which obviously you don't want to touch!

The house next door which is off the same trans. does not have this problem.
I wonder if the meter might be defective.
Thanks for your response

Look for something starting, or trying to start. It might be a motor in an old fridge or freezer. The weather is cold, so it could even be a large electric heater or furnace blower.

Ever thought about an under-sized service?
Also, have you listened to the panel to see if there is a bad phase busbar in there at all?

Thanks I will check

I would have POCO check all connections at street. I had a problem and they fixed the connection at the weatherhead and were about to leave and insisted they take a look at the street side connection and sure enough there was the problem. Old street in Weston MA, and the connections were corroded at the transformer end.

shortcircuit

Did the POCO check only the neutral connections? They should check all the connections

Had this problem before , and went round and round with power company . Turned out that they dont check connections behind the meter , I had to meet them there , they pulled the meter and I tightened loose neutral in meter base .


Sorry ,I just read you already did that . A logger at panel would tell you if it is inside or outside .

One more thought , if it is SE cable from meter to panel , check for corrosion going through concrete block , etc .

Thanks for the info, the power co is coming back to look at the pole connections.
Forgive me what is a logger I have never heard that term.
Mike

Maybe not the correct term , you hook it to the lines for say 24 hours and it gives you a line graph of the voltage over time .

The Dranitz I have uses a set point for spikes and sags, logging anything that exceeds that point.

If this is a regular occurrence, you might do as well with a simple analog meter. It is really hard to do much with a digital meter unless it will save the low point. Even then you don't know if that was just a spike or a real sag. The analog meter is far more visual.

I agree Greg,
I have an elderly analouge meter here that has the facility to set the needle at centre scale and it has +/- values printed on the scale.
In some cases, I actually prefer the analogue meter to a digital one, especially if the readings are all over the place or changing to any great degree.

Having said all that I also own a data logger, it's handy to be able to leave the thing behind (behind the panel dead-front, of course) and go and get it say two days later and see what it has recorded.
It's told me a few interesting stories to date.

When I first got my Dranitz I set it up at what I thought was a reasonable level in my office on Friday and came back the next Monday to see how I was doing. It had run out of paper.

Blast!!, you would say.

Greg said...
"It had run out of paper"

That's one of the reasons I bought a digital Amprobe Digimatic
I had the analog Amprobe chart recorders also, and remembering to have someone replace the chart roll was a pain.

Dranetz was a tool the computer guys used to love!

Hi all
Power co came, said they checked all connections at trans. pole. Customer still has blinking lights. My digitial meter only shows slight changes in voltage less than 2%.
I can not isolate the problem, shut breakers feeding anything with a motor or compressor and it still blinks.
The lights only dime intermittenly.

I think this is definitely a local problem and not part of the PoCo network.
What really needs to be ascertained, is how the lights are wired in that place.
If them lighting circuits are all sharing a common feed, I would suspect a dodgy neutral (or phase) connection somewhere in the installation.
More than likely on one of the lighting circuit home-runs.
An ohm-meter and a long piece of wire would help speed the fault-finding process up.

Mike, you never mentioned if the receptacle circuits were affected by this intermittent voltage sag problem.
Were these checked at the same time?, as that would also give you some sort of indication as to where the fault could be.

Hope this is of some help.

Hi Mike
Thanks for the info.
It affects both lights and receptacles.
The pole outside has a supporting cable with a big eye bolt in the ground acting as a restrainer since it is the last pole on the street and I noticed that the neutral wire is connected to this restraining cable.
I wonder if the path from the neatral at the trans has changed?

In case it's a bad connection between the breaker and the buss bar: If you have a reasonably good voltmeter that will read millivolts, check the voltage from the incoming wire to the buss bar. You need the panel to have a load to get a good reading. On opposite phases you'll get about 240 volts, but across a bad connection on the same phase, it might be a half volt or more, depending on load.

have you tried this?:

1. pop off panel cover
2. install a temp breaker connected to an individual light
3. turn off each breaker until the dimming stops

this is the next thing i would do

Mike, that connection is only used to ground that stay wire, or it could be some sort of ground for the neutral.
It shouldn't make any difference to your problem.

Yep, that is just a guy wire to anchor the final aerial span. Bonding it to the neutral is typical, in fact it is mandatory. Anything metallic on a utility pole needs to be bonded together, including neutrals (except for the hots, of course).

The pole's true grounding connection is via either a driven rod or a copper plate attached to the base of the pole.

I've had problems with older Seimens panels where they used a "stab in" type main breaker. To much load and the connection to the buss starts overheating and melting away. I've seen this on both 100 and 200amp loadcenters. Now they have changed their design to bolt in main.

Take a look for this...

shortcircuit

If this is happening on more than one breaker (unless circuits are sharing neutral ) it probably has to do with panel , meter , or in between . As in my previous post , SE cable running across concrete product can corrode , eating through the outer neutral braid , causing dimming etc. If you can't check this , perhaps you can run a TEMPORARY parallel neutral from panel to outside , or measure for voltage drop on entrance cable . Also check if main breaker is loose connection in panel , ie voltage drop across breaker .

Mike...did you find the cause of the blinking lights yet?

Hi
Went there today and thought I found problem with the frig, changed main breaker, but still the lights dim.
With main breaker on ,one leg to neatral draws 116.7v and the other leg draws 125.5v When main breaker is shut off, with no load, on the street side of the main the v on both legs is 121.5v.
When I shut off circuit brekers one at a time the voltage on the high lege will gradually go back down to match the volts on the other leg. The thing that is driving me crazy is I can not isolate the problem, it seems to be on multiple circuits. Could the outside meter be defective, PC has not checked it.
I have meeting to go to I will check back.
Thanks Mike

Mike
looks to me to be neutral connection ahead of the main breaker. Meter base or at the utility connection or one of their connections closer to the transformer. To date in 31 years all unbalanced voltages between 1 phase to neutral and the other phase in neutral has always been an open or resistive connection at some neutral connection. Once you have verified all the connections you are allowed to fix it then must be further upstream.
I'd get permission or have the utility break the meter seal and check the insides of the meter base.
I assume you have checked all the neutrals accessible to you?

One phase-neutral voltage reads hi under load and the other phase-neutral voltage reads low under load, AND both phases are equal under no load. Definitely sounds like a bad neutral connection. I'll bet that leg to leg voltage doesn't change much from loaded to no load. I would check the neutral splice at the weather head.

Mike
I had PC change neatral connection at weatherhead, had them back to check trans and connections, the only thing not checked is outside meter. I will have them check that too.
But now I think the problem is inside because voltage with no load at the line side of main breaker is steady as I mentioned in previous posts and when the branch circuit breakers are turned on the voltage changes. My problem is trying to isolate the trouble because it does not seem to be on one particular circuit. I shut off all circuits with motors, all 2 pole breakers that share a neatral and it still dimmes.
Mike

Sounds like you have a main going bad. Just had one were the voltage was good on the line and good on 1 leg. The other leg of the load side voltage was jumping up and down depending on the load. went from 90 to 120v. They lost a couple of power supplies on some computers that didn t have bat backup. Did water leak onto the main? What manufacturer is the main?


Ob
Sorry missed that u changed the main. I would be checking the meter neutrals and considering the lower seu cable may be failing as mentioned.

SO...what brand of loadcenter is it?

Hi
It is a Murrey panel which has a main breaker that I replaced. It is fairly new and it has 2 neutral blocks on each side connected by a flat pan cake type buss that connects to each neutral block. The service is wired with copper Se cable which looks just fine. The bonding screw is installed and connected to the neutral buss and the ground wires are also connected. The dimming will occur when any significant load is applied any where in the house. Very strange, still scratching my head.
Mike

The voltage fluctuation that you measured does not sound like enough to dim lights .
Still there should be none .
Really need to know where voltage is dropping .
If it drops at SE cable , above main then problem is before that .
Other possible causes are : loose bolts in panel , burnt bussbar , loose neutrals , loose or bad main.
It is just guessing without knowing how far back the voltage drop goes