odd light dimming issue?

[Nate Nagel]

Well, I got a little more money than I was expecting to this week, so last night I went out and bought some more tools that I thought I'd be using a lot... I've realized that there are a few tools that I've always had access to but never bought for myself, that now I have to buy because I have my own place and I'd like to be able to do work here... anyway, I got myself a new Sawzall and a 4-1/2" angle grinder, among other things. This AM I just plugged them in and ran them to make sure they worked before throwing out the packaging. The girlie yelled down from upstairs, "you know, when you turn that on, the lights dim up here..." WTF? I was using them in a 20A kitchen counter receptacle which has nothing else on the circuit. The 15A lighting circuit for upstairs is completely separate (and may or may not be on the same phase, I don't remember.) Is this an issue, and what could cause it? I'm guessing poor neutral connection at the panel?

Granted I did buy a real honest-to-god Milwaukee Sawzall and a good Milwaukee angle grinder, not some cheap lightweight crap, but I think both are rated at 10A which I would assume a 12/2 branch circuit would handle no problem.

nate

[Edwin Pawlowski]

Other factors come in play. Think of the electric supply as a water supply. There is only so many watts coming into the house. When there is a surge at one outlet, there will be a drop at another. Some tools take quite a bit of power to start up, well beyond the 10A running load. Sort of the same as when you are in the shower and the dishwasher suddenly fills.

At the same time you started up that grinder, the refrigerator, heater, TV, lights, etc were using some of the available power so a surge was very noticeable.

[Joseph Meehan]

I agree with Ed. Frankly I would be more worried if they got brighter. That would be a problem and it does happen.

The question is how much. Within reason it is normal. It also might be a good indication that your home wiring including the supply my be undersized for today's use. How old is your home?

[m Ransley]

Done asume it 12-2

[Pete C.]

It may be normal, but it wouldn't hurt to spend some time going around the house pulling outlets and switches and tightening connections along with the connections in the main panel and any sub panels. It may be a bit tedious, but you might find some developing problems.

Pete C.

[N8N]

To answer some other posters, the house was built in the late 40's but currently has a 200A service. And I *am* currently systematically going through the house replacing all the receptacles, switches, etc. and rectifying problems as I find them. I just thought it odd that this would cause dimming on circuits other than the branch circuit that I was plugged into, seeing as there's that big fatty cable feeding the main panel.

nate

[Joseph Meehan]

N8N wrote: ...

Good plan. Some heavy draw tools can do it. You may have a marginal transformer feeding your home. It is not uncommon in older neighborhoods.

[maradcliff]

Thats what I was thinking.... Also, since its a kitchen outlet, was a refrig running at the same time?

Also, is the same neutral being used for the two circuits that were invloved? If YES, carefully check that neutral connection.

Finally, install a completely separate circuit for you workshop tools. Of course we all know that those portavble tools get used in other parts of the house too.

One last thought. Is the light that dimmed connected to a dimmer? Those dimmers are often sensitive to voltage changes, and the "dim effect" is more noticable than on a common "switch only' circuit. I have seen this happen.....

If you got a meter, start watching the voltage in your house. Hook that meter to the upstairs light, and turn on your power tool in the same outlet you had it. Have the wife watch the meter, etc.... If your transformer is marginal, ALL lights in the house should dim. But then too, it depends on what other neighbor houses (on the same xformer) had running at the time too. They do sell meters that record voltages, but they are costly.

Mark

[w_tom]

That appliance draws trivial power. However wiring has a defect so significant that even light bulbs are affected. You now have a diagnostic tool to find that defective wiring - light bulb and Sawzall.

Your first discovery is electrical wiring connection between that upstairs light and Sawzall's AC receptacle. Are they on same circuit breaker? If yes, then how are they connected? If not, how are those circuit breakers related?

No one can provide a useful answer without circuit descriptions and further tests. But this you do know. That Sawzall and grinder consume minimal and irrelevant power. Even a smallest 15 amp circuit should not cause light bulb dimming. If those small power consumers affect light bulb intensity, then you have a potentially serious wiring problem.

Neutral wire is only one potential reason for failure. But then if Sawzall caused light bulb intensity change, then so did washer, dryer, furnace, dishwasher, etc. Needed: more facts including household wiring descriptions.

[pawlowsk002]

JM:

Tell me about it. My neighbor's central a/c makes my lights dim and VCR clock reset every time it kicks on. :( I think the whole bunch of us on the block should get together and turn on our dryers to get a new xformer. :D

Cordially yours: G P

[Joseph Meehan]

Just get everyone to start calling in to the power company and complaining. That will usually do it.

[Nate Nagel]

Not sure. It's on its own circuit, anyway. (one thing that's actually done right.)

No, neutral is separate all the way back to the bus in the panel.

"workshop" is a separate building :) One of the reasons I was attracted to the place.

Not the one that she was standing under... only dimmer in the house is in the dining room.

yeah, I *used* to have access to a recorder... that would be useful.

nate