Hair straightener and dimming lights

[Belton]

Just curious if anyone has come across an issue with lights fluttering while a hair straightener is plugged in to the same circuit? Situation: '60's style home, panel 12 yrs old, single ground rod, 15A circuit from a sub panel. The lights in the bathroom will dim slightly and somewhat quickly, this does not happen with a 1500W hairdryer nor a 1500W space heater. These all should be resistive type heat correct? The plate on the hair straightener says 165W (more than likely 1650W and the 0 was left off). Voltage is 121-122. Neutrals tight. I moved the breaker up in the panel and then moved it to the main panel - no change. The only time we see it is when the straightener is fully on. I have read on here posts about losing the neutral back to the transformer creating similar situations, could this be related? I would not think so since the problem seems isolated to one circuit.

Thanks for the help!

 

[LEO2854]

Just curious if anyone has come across an issue with lights fluttering while a hair straightener is plugged in to the same circuit? Situation: '60's style home, panel 12 yrs old, single ground rod, 15A circuit from a sub panel. The lights in the bathroom will dim slightly and somewhat quickly, this does not happen with a 1500W hairdryer nor a 1500W space heater. These all should be resistive type heat correct? The plate on the hair straightener says 165W (more than likely 1650W and the 0 was left off). Voltage is 121-122. Neutrals tight. I moved the breaker up in the panel and then moved it to the main panel - no change. The only time we see it is when the straightener is fully on. I have read on here posts about losing the neutral back to the transformer creating similar situations, could this be related? I would not think so since the problem seems isolated to one circuit.

Thanks for the help!

Plug in the hair straitener and take a amp reading.

 

[gar]

101203-2249 EST

Belton:

The two 1500 W devices you mention if set for full on are most likely a continuous load, and the light would have flickered once when first turned on and once on turn off.

I believe the hair straightener is probably as labeled. But to maintain a constant temperature, set by its thermostat, it rather rapidly cycles on and off. Thus, flicker is noticeable.

Assume a 100 ft loop length of #14. The resistance is about 0.25 ohms. At 2 A this is a voltage change of 0.5 V. This should not be noticeable. So put a good DVM, such as a Fluke 27, on the socket the straightener is connected to and put in min-max mode and see what the change of voltage is.

On my wife's 85 W hair curler I see a change of about 0.2 V.

You should be able to use a voltmeter to ferret out the problem location. Generally speaking at 120 nominal voltage I would expect you need a minimum of a 2V change for noticeable flicker, and that is almost imperceptible.

Do not get hung-up on it being a neutral problem. It could be anywhere in the current loop.

.

 

[Belton]

101203-2249 EST

You should be able to use a voltmeter to ferret out the problem location. Generally speaking at 120 nominal voltage I would expect you need a minimum of a 2V change for noticeable flicker, and that is almost imperceptible.

.

Gar, the difference in V was right at 2.5. The flicker was barely noticeable, but nonetheless, noticeable. I am not sure what you mean by "ferret out the problem". If the device is causing the flicker is there really a problem? I tried to replicate this "flicker" on another circuit, I saw no change. Could it be the location in the circuit of the device?

Belton

 

[gar]

101204-1741 EST

Belton:

I will assume the straightener is plugged into a duplex receptacle. Plug your meter in to one side of the receptacle that the straightener is plugged into. Actually I assume this is what you have already done. Monitor the voltage change. That is apparently 2.5 V. That is large for a roughly 100 W load.

Next unplug the straightener. Meter is still plugged in. In place of the straightener plug in a 1500 W heater and note the change in voltage. If the straightener is only in the 100 W range when consuming power, then you should expect a much larger voltage drop from the 1500 W heater.

If this is your own home, then I will wait for you to experiment.

If it is a substantial trip, then I will pass on some other things to do before you experiment. Note: one can measure Romex lengths with a 1500 W heater and a meter that reads 0.1 V on the 120 range. #12 copper is 1.6 ohms per 1000 ft, and loop resistance for a 1000 ft is 3.2 ohms. Thus, 10 ft of Romex has a loop resistance of 0.032 ohms. 12 A thru 0.032 ohms is a voltage of 0.38 V.

.

 

[hbiss]

I see this problem in offices all the time when the heating element in older laser printers and copiers cycle on and off. Matter of fact I have one in my office that's on the same 20A receptacle circuit as the under cabinet fluorescent is plugged into at my desk. The flickering reminds me about how much electric it's using so I turn the printer off when it's not going to be used.:grin:

The way around this is to have separate circuits for lighting and receptacles which is what the code now requires for bathrooms. As has been shown your situation isn't because of a problem but for a lot of reasons it might be a good time to recommend to the customer a new 20A home run with a dedicated GFI receptacle. Betcha that 15A circuit has a lot more on it than the bath receptacle and lighting.

-Hal

 

[brantmacga]

The way around this is to have separate circuits for lighting and receptacles which is what the code now requires for bathrooms.

Does it really? Is that new to the '08?

Last I recall in the '05, lighting and receps could be on the same circuit as long as the circuit only served the one bathroom.

 

[Belton]

Gar and Hal,

Thanks for the advice. I measured according to what you recommended. The drop for the heater was around 2.5. The straightener was much less. Thanks for some great information. We installed a new circuit and solved the problem. Just for your info. there was a lot of stuff on the original circuit.

These boards are a great resource!

Thanks again!

Belton