Does this happen often, and in what circumstances could this be a Bad Thing?
Most people think that circuit breakers exhibit a “step function”- under 15A, and the breaker passes the current, over 15A and the breaker trips instantly. This is far from the case, and wouldn’t be desirable. A common 200W incandescent lamp might pull over 20A the moment it is turned on, and the would cause nuisance tripping of such a circuit breaker. Breakers have trip curves that look something like this.
Note that even 2x overcurrent requires several seconds to cause the breaker to trip.
He is not having an issue with the breaker blowing, his issue is dim lights while his hairdryer is running, not just when he turns it on but the entire time it is running. If he has a circuit rated at 15 amps and his breaker is 20 amps he may be running close to 20 amps and overloading the circuit not the breaker. Sounds more to me like resistance in the circuit somewhere anyway. His entire house dims down, not sure how many circuits he is on.
The OP has came back to say it is only the bathroom lights that are dimming. And his house is 45 years old.
So I doubt that the problem is in the main. Because if it was the main everything would dimming.
He did mention the fan slowing down, I am going to assume it is also in the bathroom.
Today there would be seperate circuits for lighting and power. My house 36 years old has one circuit on the 15 amp GFI breaker and it feeds all outside lights, most bathroom lights, and all bathroom outlets. WE had problem tripping the breaker when my wife used her hair dryer and anyone else did anything in the bathroom using power. We looked for a new hair dryer a smaller one. The smallest one she could find in the stores was 1800 watts. We pulled a new circuit to our bathroom.
Now for the OP. The hair dryer will be large enought to dimm the lights in the athroom if they are on the same circuit. Check to see if you have breakers or fuses. If breakers locate which breaker is for the bathroom. Turn it off and see what else goes off. This will give you an idea of the load on the breaker. Ifd you can take a voltage reading at the outlet with and with out the hair dryer.
The voltage drop if excessive can be caused by a bad connection in a electrical box between the paneland the outlet. A bad connection at the breaker. A bad breaker. A bad connection between the breaker and the buss bars. And it can also be caused by a high load and a long line between the panel and the outlet.
Well, when the blow-dryer is running in the bathroom, the bathroom lights dim to about half and the box fan in bedroom #1 slows down to about half speed.
However, when the blow-dryer is running in bedroom #2, it doesn’t seem to affect anything.
Do these facts change the diagnosis?
A 50% drop in room lights and fan speed is significant, and can’t be attributed to I²R losses. I agree with the previous poster who suspects a high resistance in the circuit. But since only the bathroom is faceted, most likely the breaker supplying that room (screw terminal might be loose) or a loose wire nut joint somewhere in the feeder.
Hard to say exactly where it is, and best to have an electrician look around.
I was answering** Leo Bloom.**
No.
You probably have different circuits involved and the bathroom one has less reserve capacity or other problems. A safety inspection would be wise.
Circuits in residential properties are not neatly laid out one per room. When the construction was going up, the electrician probably stuck outlets and lights where convenient for him before the walls were put in. Later remodeling can make this worse. It’s not uncommon for circuits to span parts of different, adjacent rooms.
Yes, I neglected to also mention that about five years back we replaced both bathroom outlets.
Does that change anything?
The consensus here seems to be that this problem may turn out to be no big deal, but better to have an Electrician diagnose the problem and fix what is needed, than just letting it go and taking my chances with an electrical fire. This seems like very good advice from you folks and thanks to all.
My plan is to schedule an appointment with an Electrician Monday a.m. and definitely stop using the blow-dryer for now.
No. From the amount of loss you’re experiencing, I’d say the early posts in this thread are correct, and you’re wise to get somebody in there to check your panel and devices out for any loose connections.
Did you use the screws on the outlets to wire them in, or use the holes in the back? If you used the holes, it’s slightly possible that had an effect, since those connections aren’t as solid as using the screws, and can become loose.
If you’re comfortable with it, you could make sure you’re using the screws, and that the connections are solid, since that’s easy to do.
OK a 50% dimming is not good. Are both bathrooms on the same circuit? If they are sounds like a bad connection between the two bathrooms and the connection is probably heating up ie fire danger. I would call in some help here.
If the bathrooms are on seperate circuits (not probable but possable) there is still something very bad here. If the drop is due to just line losses this would indicate an overamping issue and the breaker should trip. Or again it could be just a bad connection some where.
Bingo we have a winner here. When haveing a problem goto the last place worked on before problem showed up. If you daisy chained through the 1st bathroom outlet (always a bad idea) you may have a good connection into the outlet of the 1st bathroom and a bad connection on the connection of the pass through.
The wires should all come into the electrical box and be spliced together with a pig tail left for the outlet to be connected to.
If you replaced the outlet and daisy chained through the out let go back and correct. If you spliced in the electrical box go back and check the splice. Check both hot and neutral.
so I have same issue, actually G friend is in her bathroom, attached to her room I am in a seperate room with my sound equipment and I see on my Furman Power conditioner voltage drop from 120 downto 104 which sets voltage range warning on power conditioner.
This makes me feel very uncomfortable that is huge drop.
BTW I can make lights dim to the bass of my pro audio system when turned up to around 70% which is super insane loud and crazy almost painful loud.
Have system with 4200 watts of Peavey Commercial Series amp power lol
but voltage drop is with me at 1%or idle watching voltage display which is why I am very worried.
If you’re worried about it, have an electrician run a separate, dedicated 20-amp circuit from the panel to your sound equipment.
But modern switched-mode power supplies for electronics are pretty tolerant of voltage changes, and you also have a power conditioner to protect your gear from major drops or surges. It’s probably not worth losing sleep over.
American electrics are scary sometimes. If my lights dimmed when my wife used something as low wattage as a domestic hair dryer, I would first try another appliance in the same outlet to check that the dryer wasn’t faulty; then be on the phone straight away for an electrician and ban the use of the dryer until the fault is rectified.
The problem is clearly an overloaded circuit and if it’s not the dryer, then there is a risk of overheating the supply wire.
:rolleyes:
one person with a problem of possibly their own making (the OP) and one person LOLing at how running 4200 watts of amplification on an 1800 watt circuit dims his lights says nothing about the entire country.
How modern? None of the homes I’ve lived in had the lights on a separate circuit. ISTR the circuits were always done room by room, more or less. (Could be that none of the homes were wired recently enough that you would consider it to be “modern”.)
My house was built in 2001 by a builder not known for cutting-edge construction methods, and all the outlets are on different circuits in the breaker box than the lights in the rooms.