I recently purchased a house which was built in 1938, and have been doing a number of things to improve it. For Christmas, I got a new mitre saw, and set it up on the workbench in the basement. The first time I ran it, my wife noted that it caused most of the lights in the living room to dim. I did a little checking, and sure enough: half the living room, the basement workbench outlets and lights, and 4 of the basement light fixtures are all on the same circuit. I'm assuming the only way to fix this is to put the workbench on its own circuit, which is something I wanted to do anyway... but I used the last available spot in my breaker panel when I installed the dishwasher. As I see it, I have 2 options: Install a larger panel, which would require the inconvenience of having the electric company shut off my power for the better part of a day, or install a sub panel next to the main panel. Is there another option? Is one of my two options safer, or better in some way that I'm missing? Also, what codes would I need to be aware of for both options?
wfischer
Do the lights dim for just a moment, or all the while the saw is cutting?
It is not unusual for lights to dim for just a moment when the saw starts up even though the saw draws much less than 15 amps while it runs. It just draws a lot more upon startup. If you are not blowing the breaker you probably do not have an overload problem for the time being.
You could see if your panel accepts a double breaker (for two circuits and has two handles) that fits in the same space as one original breaker. Then you can run a separate circuit.
Even with a separate workshop circuit, it is possible that some dimming of lights will still be experienced. This depends on the stability of the electrical system out to and including the pole transformer.
You are more likely to have dimming problems if receptacles, switches, etc. are wired using the back stab holes instead of the screw on terminals.
It is not unusual for lights to dim for just a moment when the saw starts up even though the saw draws much less than 15 amps while it runs. It just draws a lot more upon startup. If you are not blowing the breaker you probably do not have an overload problem for the time being.
You could see if your panel accepts a double breaker (for two circuits and has two handles) that fits in the same space as one original breaker. Then you can run a separate circuit.
Even with a separate workshop circuit, it is possible that some dimming of lights will still be experienced. This depends on the stability of the electrical system out to and including the pole transformer.
You are more likely to have dimming problems if receptacles, switches, etc. are wired using the back stab holes instead of the screw on terminals.
Thanks for the info on tandem breakers! That looks like the easiest (and least expensive) way for me to go.
AllanJ: The only thing I've cut with that saw so far is 11/16" quarter round, which takes literally less than a second... so I couldn't really say.
And while I haven't blown a breaker yet, I'm planning some upgrades for the basement area that I wouldn't trust to be on the existing circuit, as it stands.
AllanJ: The only thing I've cut with that saw so far is 11/16" quarter round, which takes literally less than a second... so I couldn't really say.
And while I haven't blown a breaker yet, I'm planning some upgrades for the basement area that I wouldn't trust to be on the existing circuit, as it stands.
According to the sticker inside the door, it's a Square D QO Load Center, Cat. No. QOC-16M Series L1
Okay, here's an update: Last night I took the front cover off the panel, and discovered a sticker inside that includes additional wiring information. According to this sticker, if I'm reading it right, tandem breakers can be used in spots 13-16. 14 and 16 are the ones that power almost the entire house anyway, so that works out perfectly.
On a related topic, is there any reason to use a breaker larger than 20A for a household 120V line, aside from dedicated appliance circuits?
On a related topic, is there any reason to use a breaker larger than 20A for a household 120V line, aside from dedicated appliance circuits?
Just when you thought this thread was done...
I went down to Home Depot yesterday to do some pricing, and I took a few moments to look at breakers. The breakers in my panel now are the equivalent of a Square D QO120CP (tried to find a decent picture, but couldn't). The closest tandem breaker I could find was a QOT2020CP (again, no decent pictures). The thingy (for lack of a better term) that holds the breaker in the panel, the one that's not connected to any power, is different on those two breakers. Will that particular tandem work, or do I need to go look again?
I went down to Home Depot yesterday to do some pricing, and I took a few moments to look at breakers. The breakers in my panel now are the equivalent of a Square D QO120CP (tried to find a decent picture, but couldn't). The closest tandem breaker I could find was a QOT2020CP (again, no decent pictures). The thingy (for lack of a better term) that holds the breaker in the panel, the one that's not connected to any power, is different on those two breakers. Will that particular tandem work, or do I need to go look again?
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