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Discussion Starter #1
Here is a mystery I'm trying to solve: My supply box is rated at 200amps, which is way more than enough for my tiny rancher. I use a ceramic space heater in the basement which is powered from an outlet near the box. When heating, the speed of the fan can vary from time to time, sometimes slowing to a crawl. I also notice that the lights also vary in brightness. The weird thing is that there are no major power consuming systems in the house that are running when this happens. What could be the cause - could it be the mains quality supplied to the house?

To add to that, it has happened with several space heaters. I've also measured the voltage coming to the heater and it does not seem to be the cause.
 

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Discussion Starter #3
Thanks for the tips! The service panel is easy, however there are rats' nests of old wiring I cannot even begin to comprehend in parts of the house. I'll get the tester and start testing!
 

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if you have old wiring I bet some of the circuits are not grounded (two wire). If later new grounded circuits got added the collision of the two types may be the source of your problem. You may need a serious upgrade of your circuits. If some DIY happened along the way who knows what is going on.
 

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I suspect that the cause is likely loose connections in the wiring. Like anything else, wires expand and contract as they heat up and cool down. This causes the connections in the wiring to loosen over time. Loose connections heat up more, which causes them to loosen even more. This can be dangerous if left unchecked. The bad connections will eventually arc and can cause fires. The most common place for this to happen is at the connections at the back of your outlets, since wires daisy chain from outlet to outlet. The worst culprit are the outlets with the push on "back wiring" rather than screw on terminals. I would suggest that your best testing tool is a volt meter. You don't need anything fancy. You can get a cheap one at Harbor Freight for under $5. https://www.harborfreight.com/7-function-digital-multimeter-92020.html, or free if you use one of their coupons.

I will say that my favorite tool for measuring and testing power line voltages is the old RCA WV-120 series. http://www.indianaradios.com/RCA WV-120A Power Line Monitor.htm Every radio and TV repair shop in the country used to have at least one of these (back when there were radio and TV repair shops. Ha ha) You can usually find them on eBay, starting around $30 or so. I have a few, including one that permanently "lives" on the kitchen counter. (Yes, my wife approves, knows how to use it and will report it to me if the voltage is ever low.) They have an expanded scale from 100 to 140 so that you can instantly read the approximate voltage from across the room. It is much easier to read at a quick glance than a digital meter. If the voltage is fluctuating, the digits on a digital multimeter can fluctuate and jump all over the place. An analog meter will simply swing left and right.
 

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Discussion Starter #6
Thanks guys, I have my work cut out for me! The funk is heavy with the wiring in this house. One circuit powers an outlet in the master bedroom, the kitchen fan and the outside floodlights. Most is old MC cable without a dedicated insulated ground wire, and there are a couple of ungrounded outlets. I could write a book about the wiring. Let me use the next few months to thoroughly sort out the wiring. Thanks!
 

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Electrician here. Curious if the plug "close to your panel " is on the same circuit or phase with your lighting circuit (?) (When your heater comes on- lights are dimming) I would get an electrician buddy to come over, pop off the panel cover and see if this plug is doubled up on your lighting circuit. Is the electrical panel door legend up to date? Quick and dirty investigation to check this is to plug a portable radio/ plug checker into your receptacles and shut off one circuit at a time....create a new/ updated panel legend. You have lots of room with a 200 amp panel. Lighting and receptacle circuits should be separate . Hope this helps a little further...
 

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When you say the lights and fan dim , are you saying in the same room as the outlet you are plugging the heater into? If so , test like the others suggested , find the breaker that supplies that outlet , and see if it also controls the fan and lights . Check what the amp rating of that breaker is , if it's 15 amp , then I will almost guarantee you are overloading the circuit .

Space heaters take a ton of power , it's not uncommon for one to overload a dedicated 15amp circuit . Look at your heater and find the wattage rating , divide that by 120 (volts) , that will tell you how many amps it should draw . The draw typically doesn't start at that level , and from what I've seen and tested they can go over their rated draw .

If the heater is on a 15 amp circuit I wouldn't use a heater rated over 1200 watts , on a 20 amp , 2000w would be pushing it with other loads on the circuit .
 

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Discussion Starter #9
When you say the lights and fan dim , are you saying in the same room as the outlet you are plugging the heater into? If so , test like the others suggested , find the breaker that supplies that outlet , and see if it also controls the fan and lights . Check what the amp rating of that breaker is , if it's 15 amp , then I will almost guarantee you are overloading the circuit .

Space heaters take a ton of power , it's not uncommon for one to overload a dedicated 15amp circuit . Look at your heater and find the wattage rating , divide that by 120 (volts) , that will tell you how many amps it should draw . The draw typically doesn't start at that level , and from what I've seen and tested they can go over their rated draw .

If the heater is on a 15 amp circuit I wouldn't use a heater rated over 1200 watts , on a 20 amp , 2000w would be pushing it with other loads on the circuit .
That's not quite what happens. The power fluctuations are random, and the lights are on a different circuit and dim independently of the heater. I use the space heater on the 750W setting. Thanks for the suggestions anyway. I'll start to look into the power problems sometime in mid-Jan, there is a lot to investigate.
 

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If it's independent of the heater , and you don't have any other loads , typically motor loads that may be causing the fluctuation , then I would lean toward saying it's a delivery issue . Just because you like in a major metro area doesn't mean the supply is steady or constant .

http://www.p3international.com/products/p4400.html

That can plug in and monitor the voltage you are getting , if you aren't comfortable with a volt meter and opening the panel to test . Test both legs that come to your house , there may be a failing transformer in your neighborhood , or one of the lines coming to your house could be corroded and causes voltage drops in the breeze .

If you are reading voltage drops more than 2-3% of what you are supposed to be getting or so , contact your utility provider , exaggerate the amount of drop because they often don't want to bother , or will tell you theres no problem from the office . The field techs are usually good about checking . If you can , check a neighbors voltage for comparison . If yours is off and his is constant , it's probably the feed to your property , if both are goofy , transformer in the area or the substation .
 

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I'm not sure about the lighting, but the heater problem may be motor related. Especially since you say this has happened before. It's possible your motor's bearing are bad. The fan will start slow, but as the heater temp increases the bearing's grease becomes more fluid and allows faster rotation. I saw this happen many times in Industry. Motors run for years, but take them down for a short time and the bearings seize and the motor won't come back up. +1 on using a higher amperage circuit. Most heaters I've seen are 1500W at 120V you're right at the limit of the 15A breaker.
 

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Discussion Starter #14
Thanks. It's not motor related as it happens with every heater I've used. I use a 1500w heater on the half power setting.
 

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Discussion Starter #15
The mystery continues. I tested all outlets and to my surprise they all check out fine. I doubled-checked all the connections in the service panel and they were all tight too. I ran a new 20A line to an outlet in my Ht area, which is right next to the service panel. I used that to power a radiant heater. Now the microwave in the kitchen, which is on the opposite phase, buzzes and runs at half power whenever the heater is on :confused:. I'll be calling professional help soon..
 

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Discussion Starter #17 (Edited)
I've been trying to clean up the lines that I could in preparation for professional help. One run to the outlet that powered the sump pump looked more like 16 gauge so I got to changing it to 12/2. While examining the panel I heard a faint arcing sound from one of the breakers. I traced it to the 30 amp breaker for the dryer line. I removed the breaker and found some stuff on the terminals that looks like flux. After I changed the breaker the house has been calm. Not 100% sure all problems are solved but I believe it is a major one out of the way.

* A note that thankfully the dryer was running at the time, which was the only time the arcing was triggered.
 

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Discussion Starter #18
Just to wrap this issue up. The other day I woke up to wildly fluctuating power - from 9V to 160V! I called the power company and they found a damaged line to the house that a tree branch had been tearing apart over the years. All mains power problems have since vanished.
 
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