Help with power quality issue at MY house.

[brantmacga]

I'd like some input for a problem at my house.


I have a problem with lights flickering/dimming and voltage drops at small appliances.

When I moved in about 5 years ago, the house had a 150A service. I did a complete upgrade to a 200A; new meter & disco/panel outside, new 200A panel inside.

I spent some time measuring loads on circuits and getting my service as balanced as possible.


I've always had a slight voltage issue, but i think its getting worse.


I have an overhead-to-underground service. I've noticed that in storms or high winds, i'll get a severe voltage drop.

I'm thinking maybe there is a loose connection, possibly at the transformer. Its about 200 yds. away on a pole. Does this seem likely? I have checked and rechecked every lug and screw on my service and they're all tight. Or it could be possible my overhead drop size needs to be increased. I say that because when my heat was running over the winter, my voltage was slightly lower and i noticed a very slight flicker in the lights, and they were just a little dimmer.

Or another possibility; Once when I was checking lugs, I had a loose neutral in the disconnect outside. this was right after a storm and i was trying to trace a flicker. I wonder if its possible there is a loose neutral in the meter base?


its been slightly more noticeable today, and all my clocks in the house were flashing so at some point it was off during the day. i don't know if they were working on it upstream or what.

I've been wanting to call the POCO to come check things out, but I wanted to make sure i've covered everything on my end first. all the guys down there at the office know me and what i do. Should I just call them and see if they can figure it out? I think I've exhausted everything I know of on my end.

 

[quogueelectric]

I'd like some input for a problem at my house.


I have a problem with lights flickering/dimming and voltage drops at small appliances.

When I moved in about 5 years ago, the house had a 150A service. I did a complete upgrade to a 200A; new meter & disco/panel outside, new 200A panel inside.

I spent some time measuring loads on circuits and getting my service as balanced as possible.


I've always had a slight voltage issue, but i think its getting worse.


I have an overhead-to-underground service. I've noticed that in storms or high winds, i'll get a severe voltage drop.

I'm thinking maybe there is a loose connection, possibly at the transformer. Its about 200 yds. away on a pole. Does this seem likely? I have checked and rechecked every lug and screw on my service and they're all tight. Or it could be possible my overhead drop size needs to be increased. I say that because when my heat was running over the winter, my voltage was slightly lower and i noticed a very slight flicker in the lights, and they were just a little dimmer.

Or another possibility; Once when I was checking lugs, I had a loose neutral in the disconnect outside. this was right after a storm and i was trying to trace a flicker. I wonder if its possible there is a loose neutral in the meter base?


its been slightly more noticeable today, and all my clocks in the house were flashing so at some point it was off during the day. i don't know if they were working on it upstream or what.

I've been wanting to call the POCO to come check things out, but I wanted to make sure i've covered everything on my end first. all the guys down there at the office know me and what i do. Should I just call them and see if they can figure it out? I think I've exhausted everything I know of on my end.

Usually flickering problems like this are an overloaded POCO xformer. If the homeowners premise wiring is compromised I would check this out first. You seem like a pretty bright electrician so this seems doubtfull that a burned or loose connection would be the problem.. Check the screws on all terms in your meter /panel first. Then call poco and get them involved if this does not fix the problem.

 

[ItsHot]

Brant, could be a problem at poco's side. But don't forget your inground!!

 

[brantmacga]

Usually flickering problems like this are an overloaded POCO xformer. If the homeowners premise wiring is compromised I would check this out first. You seem like a pretty bright electrician so this seems doubtfull that a burned or loose connection would be the problem.. Check the screws on all terms in your meter /panel first. Then call poco and get them involved if this does not fix the problem.

Yes I've checked everything at my house; every connection.

The voltage issue with the heat running leads me to think you may be right with the transformer. It could be that coupled with too small of a drop; like I said it used to be a 150A service.

I think there is only one house sharing a transformer with me. Mine sits across a field between two other houses, and I'm almost certain the third house is sharing a transformer with our grain silos and fueling station.

 

[Buck Parrish]

Be sure and tell the poco it is an intermitent problem. Or they may send some one to check power at the meter. If it's good they leave.

If you get some one that is reasonable at the poco they will check their connections. I have it happen all the time at customers houses. Some times I would rather the problem was below the meter. Then I can get paid for fixing it.:wink:
But when you look up and see four or five old connections on a brand new service. Then you got to figure it is only as strong as it's weakest link.
It even happens at the transformers connections . Even under ground services

 

[brantmacga]

Brant, could be a problem at poco's side. But don't forget your inground!!

its crossed my mind. i've checked the lugs at both ends and they are fine. the underground portion is about 30', and in conduit. I haven't meggered those conductors though.

 

[brantmacga]

Some times I would rather the problem was below the meter. Then I can get paid for fixing it.:wink:

oh i agree. but this is my house. and i don't think my wife is going to cut me a check for repairs.

 

[ItsHot]

its crossed my mind. i've checked the lugs at both ends and they are fine. the underground portion is about 30', and in conduit. I haven't meggered those conductors though.

The conduit helps rule that out, but you never know?? Keep us posted on what you find . Good luck!!:smile:

 

[Buck Parrish]

oh i agree. but this is my house. and i don't think my wife is going to cut me a check for repairs.

Oh when I said "below the meter" I was meaning on the load side of the meter.:wink:
I didn't want to confuse that with a underground latteral.
A round here the poco does almost all the under ground latterals all the way to the meter. I'm in NC right now will head back to IN this week end.


Oh and it sounds like you have all ready done quite a bit of work to the house. I hope you got taken out to dinner. Or are you one of those guys that can send a crew of yours to go by and change the service.

 

[brantmacga]

Oh when I said "below the meter" I was meaning on the load side of the meter.:wink:
I didn't want to confuse that with a underground latteral.
A round here the poco does almost all the under ground latterals all the way to the meter. I'm in NC right now will head back to IN this week end.

yeh i knew what you were referring to.

 

[brian john]

brat:

Do a search on this and read what I posted elsewhere in the MH forum.

 

[gobblerhuntr]

Call the poco it is more than likely their problem, I work for a poco and we see this problem everyday.

 

[Sharpie]

Did you ask the neighbor who shares the same x-former if they're having any problems?

 

[gar]

090311-0903 EST

brantmacga:

Find a substantial load for a test tool. I use a nominal 1500 W heater. Its hot resistance is 10.6 ohms. On this morning's test at 122.1 V that is 11.5 A.

At my main panel this morning on phase A the voltage was 123.1 adding the heater at the panel the voltage dropped to 122.1 V. This is a 1 V change for 11.5 A change. Thus, the source impedance is 1/11.5 = 0.087 ohms. This is the total impedance of the transformer, wire, meter, and breaker.

Using a different phase A breaker to feed the heater than the meter the change in voltage for the heater load is 0.6 V. Thus, the impedance from the main panel phase A bus bar into the transformer is 0.6/11.5 = 0.052 ohms. This eliminates the impedance of the breaker and its connections, and a short length of #12 and the outlet screw terminations.

The second test is to monitor phase A with the voltmeter, I am using a Fluke 27, and put the resistive load on phase B. No change in the reading on phase A, not even 0.1 v.

This tells me the neutral is good all the way from inside the transformer to the neutral in the outlet to which the meter is connected.

I suspect that in my case much of the impedance is in the transformer. Note: there was no detectable voltage drop on service lines or it would show up when the load was on phase B as a change from this load thru the neutral resistance and its effect on the phase A voltage reading. My service lines are 0000 copper. You will see more voltage drop on your service lines because they are longer and likely smaller.

Another test you can run assuming the transformer center tap is connected to a ground rod at the pole is:

Be careful because under some conditions you could get a large voltage drop. There could be unknown conditions that produce a large voltage gradient across your yard. This would occur in close proximity to ground rods, means inches to a few feet, and would result from an open neutral.

Connect a wire to the pole ground rod or to a 10" or 12" long screwdriver probe into the ground adjacent to the pole ground rod. An extension cord is a good wire choice because the terminals are insulated. Use a high impedance voltmeter, AC volts and maybe MV range, from the conductor that is connected to the pole probe to wherever you want to make a measurement. I suggest using the EGC wire of the extension cord. With load on in the house I would make some voltage measurements to the earth as you move toward the house. If the neutral is good these voltages should be small. The highest I get in my yard is about 100 MV (0.1 V) and that is between my yard and a neighbor's that is on a different transformer. Between my transformer and my house I get more in the 50 MV or less range.

Continue approaching your home and then measure the voltage at any EGC terminal on an outlet. This then gives you a voltage measurement from something close to the center tap of the transformer to the neutral bus in the main panel because the EGC in the house is connected to the neutral bus in the main panel or thereabouts.

This is a different way of estimating the neutral drop than my change of load method.

If you are seeing multi volts in the ground probing test, then I would suspect a neutral problem. I can not give a precise definition of multi volts, but 10 certainly is, and 1 may not be.

.

 

[Mr. Bill]

If we're just tossing ideas out I'll say the transformer is undersized. How many times has the house's service size increased? Did the Utility transformer ever change? Does the transformer look discolored. May be a sign that it over heated and 'baked' the paint off. Do any other houses share this transformer? Do they have problems?

 

[gar]

090311-1009 EST

My present voltage drop form the transformer pole, using the phone co. ground wire, (the earth is still solid ice and I could not put the screwdriver into the earth) to the conduit on the outside of the house is
60 MV.

This conduit is directly bonded to the main panel enclosure and thus the EGC and neutral.

The transformer ground wire is encased with some sort of protective cover, and therefore not accessible.

.

 

[charlie]

Do you know a good electrical contractor?

Call the poco it is more than likely their problem, I work for a poco and we see this problem everyday.

Seriously though, I agree the the turkey hunter 100%. Contact your serving electric utility. 200 yards away and an overloaded transformer spells low voltage.

 

[brantmacga]

i walked out there when I got home to take a look.

so it turns out, i'm the only house on this transformer. the other house I thought shared with me has its own sitting next to mine.

the only thing on at my house was a couple of ceiling fans, a couple of lights and the fridge.

the transformer looks to be very old, and it was humming.

 

[quogueelectric]

i walked out there when I got home to take a look.

so it turns out, i'm the only house on this transformer. the other house I thought shared with me has its own sitting next to mine.

the only thing on at my house was a couple of ceiling fans, a couple of lights and the fridge.

the transformer looks to be very old, and it was humming.

Might be low on oil. Call poco.

 

[RJohnsonMasterElectrician]

Usually flickering problems like this are an overloaded POCO xformer. If the homeowners premise wiring is compromised I would check this out first. You seem like a pretty bright electrician so this seems doubtfull that a burned or loose connection would be the problem.. Check the screws on all terms in your meter /panel first. Then call poco and get them involved if this does not fix the problem.

How many houses are on that one transformer?