I think we have an issue with the neutral coming to our house (North America, split-phase power 240VAC total, two legs of 120V to neutral with opposite polarity.) Most of the time, everything is fine, but sometimes, our lights will pulse brighter, dimmer, brighter, dimmer with 1Hz frequency. At first I had no idea what the source was, but I later realized it coincides perfectly with PID heater cycles on my home espresso machine, which pulls about 5A.
The really interesting thing is that lights in the dining room get brighter at the same time that lights in the bathroom get dimmer, and vice versa. This got me thinking it was the neutral moving, as opposed to either line sagging. So, I've waited patiently for the rare moments when the problem appears and taken voltage measurements everywhere imaginable. It's not isolated to any portion of the house. All of the power in the house is doing this, all the way back to entrance lugs in the breaker panel. The line voltage from L1 to L2 is remarkably stable, maybe 0.1-0.2V fluctuations at any given time. But the line to neutral voltage during these events goes up and down by as much as 4V.
So for example, if I've got 244V total coming in, usually each line reads 122 to Neutral. During one of these events, L1 will fluctuate between about 122 to 126, while at the same time L2 is fluctuating between 118 to 122. The L1-L2 voltage always stays very stable, but the neutral moves around between them.
A variation of 4V due to a 5A load implies 0.8 ohm resistance on the neutral for the whole building, which seems abnormally high. What's far more upsetting is the intermittent nature of it. Sometimes the neutral is solid, and other times it dances around, anywhere from 1-4V in response to this 5A load (the 5A PID loop is ALWAYS cycling, on 24 hours/day, and usually its effect on mains voltages is only measurable at the outlet it's connected to - it's only during these rare "events" that the whole house has its neutral move in response to the 5A load.)
I've read horror stories all over the internet of floating neutrals and the terrible things that can happen to your appliances (or people) as a result of unpredictable household voltages when the neutral is floating... and I've also heard of "High Earthing Resistance of Neutral at Distribution Transformer" (item 4 about halfway through this article: https://electricalnotes.wordpress.com/2012/07/28/impact-of-floating-neutral-in-power-distribution/) which seems like a better fit for what I'm measuring. If it were actually floating, I'd expect voltage readings to be all over the place. As it is, it never moves too terribly far.
So, any advice on what I do next? The problem exists all the way back to the breaker box. I'm not comfortable trying to open up the meter, so I can't inspect connections from the panel to the meter, nor from the meter up to the drop. I've taken a few pics of the junctions at the mast where it drops down to the meter, and I can't see anything wrong - the wires look old and manky, but presumably bare wire always looks funky, and it's only the junctions I should be worried about? I also looked up at the power pole and the connections there - it's a rat's nest of junctions to get from the "real" neutral to the one feeding my house, so I imagine any of several joints up there could be the issue. If I can't prove the issue is outside of the house, do I need to get an electrician out first to inspect the few things I can't (won't/shouldn't) get into, or should I go straight to contacting the power company and hoping they can find an issue at the pole or mast?
I've attached a few pics which may or may not be helpful... In one version of the pole transformer pic I tried tracing each wire and color coding them to make it easier for me to follow.
The really interesting thing is that lights in the dining room get brighter at the same time that lights in the bathroom get dimmer, and vice versa. This got me thinking it was the neutral moving, as opposed to either line sagging. So, I've waited patiently for the rare moments when the problem appears and taken voltage measurements everywhere imaginable. It's not isolated to any portion of the house. All of the power in the house is doing this, all the way back to entrance lugs in the breaker panel. The line voltage from L1 to L2 is remarkably stable, maybe 0.1-0.2V fluctuations at any given time. But the line to neutral voltage during these events goes up and down by as much as 4V.
So for example, if I've got 244V total coming in, usually each line reads 122 to Neutral. During one of these events, L1 will fluctuate between about 122 to 126, while at the same time L2 is fluctuating between 118 to 122. The L1-L2 voltage always stays very stable, but the neutral moves around between them.
A variation of 4V due to a 5A load implies 0.8 ohm resistance on the neutral for the whole building, which seems abnormally high. What's far more upsetting is the intermittent nature of it. Sometimes the neutral is solid, and other times it dances around, anywhere from 1-4V in response to this 5A load (the 5A PID loop is ALWAYS cycling, on 24 hours/day, and usually its effect on mains voltages is only measurable at the outlet it's connected to - it's only during these rare "events" that the whole house has its neutral move in response to the 5A load.)
I've read horror stories all over the internet of floating neutrals and the terrible things that can happen to your appliances (or people) as a result of unpredictable household voltages when the neutral is floating... and I've also heard of "High Earthing Resistance of Neutral at Distribution Transformer" (item 4 about halfway through this article: https://electricalnotes.wordpress.com/2012/07/28/impact-of-floating-neutral-in-power-distribution/) which seems like a better fit for what I'm measuring. If it were actually floating, I'd expect voltage readings to be all over the place. As it is, it never moves too terribly far.
So, any advice on what I do next? The problem exists all the way back to the breaker box. I'm not comfortable trying to open up the meter, so I can't inspect connections from the panel to the meter, nor from the meter up to the drop. I've taken a few pics of the junctions at the mast where it drops down to the meter, and I can't see anything wrong - the wires look old and manky, but presumably bare wire always looks funky, and it's only the junctions I should be worried about? I also looked up at the power pole and the connections there - it's a rat's nest of junctions to get from the "real" neutral to the one feeding my house, so I imagine any of several joints up there could be the issue. If I can't prove the issue is outside of the house, do I need to get an electrician out first to inspect the few things I can't (won't/shouldn't) get into, or should I go straight to contacting the power company and hoping they can find an issue at the pole or mast?
I've attached a few pics which may or may not be helpful... In one version of the pole transformer pic I tried tracing each wire and color coding them to make it easier for me to follow.
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