flickering and brown outs

paulmars · Mar 21, 2021

This is in my home and none of my neighbors have this issue. Two of us get power from the same wire coming from one electrical pole. He says he don't have this issue either, but I must consider that maybe he just don't notice.

Occasionally (like once or a few times a day) lights flicker and/or go dim for one to a few seconds. It might happen once or repeat itself once or twice after the span of 5 or so minutes. Then it might not happen again for hours or until the next day. The filament bulbs are the only ones to dim. The LED and fluorescent will flicker, but not dim. I think that is because of the bulb's circuit capacitance.

The vent fan in the bath will audibly slow on occasion for a few seconds. Nothing else in house appears to be effected, but that might be because most other things here (like computers) have internal regulated power supplies to safeguard against this. Maybe it would occur with my blender, but i just haven't used it at the right time.

Ive confirmed that this occurs on four different electrical circuits. It was noticed one two, then I left the lights turned on for two more electrical circuits for the last two weeks and noticed occasional flickering in those circuits too. Both had fluorescent, so I swapped with filament and now I see flickering and brownouts, all just lasting 1 to a few seconds.

Everything in the circuit box looks good and feels tight.

I have my DVM left plugged into an electrical outlet, but I never get there fast enough to see the brown out voltage.

Ideas?

tks,
pa

timhoward · Mar 21, 2021

As you have realised the cause can be external or internal to your installation.
If they are lasting seconds I'd say they definitely need investigation further.

You really first need to rule out anything internal to your own installation causing it. You said you have checked CU connections and observed the effects on several circuits which is a helpful starting point.
I think the only other thing you can try yourself is isolating fixed equipment such as extractor fans, electric heaters, immersion heater, storage heaters, boiler etc. and patiently waiting to see if it still happens.

But I think its now time to get someone in. They will be able to test the fixed wiring and confirm there are no issues such as degrading insulation causing arcing, degrading old cables causing high resistance, faulty main switch or breaker etc. Once the wiring is tested and verified as ok the DNO can be asked to check their connections in the cut-out.

Are there certain times of day it is more likely to occur?

SJD · Mar 21, 2021

As above, time to get the consumer unit/fuse box and wiring checked out.

Might be worth checking if the brown out occurs when a particular circuit / appliance is used, e.g. a high current appliance such as a cooker, shower. If so, might be a symptom of a poor connection somewhere e.g. in the consumer unit.

timhoward · Mar 21, 2021

Funnily enough I had similar symptoms at a property last week but luckily the cause was very obvious:

How I found it inside:

(It was a privately owned internal meter before anyone kicks off about opening it!)

Lucien Nunes · Mar 21, 2021

Note the OP is in the USA where they don't have DNO's or CU's.

You are correct that some devices can ride-out momentary brownouts due to their power supply reservoir capacitors and internal regulation.

If your neighbours are genuinely unaffected, and everything at your panel is good, the intermittent connection might be at your meter socket, where you can't get access to check. Do you know whether it affects both your hot legs or just one? Do you ever get symptoms of the voltage increasing rather than decreasing? That would be indicative of a bad neutral connection. Does adding more load change anything?

You can get DMMs with max. and min. logging function, but in theory if you've checked that the problem is present on multiple circuits, and the main connections to the panel are not overheating, it's very likely to be the PoCo's responsibility and they will probably install a voltage logger themselves if they can't find the fault.