The lights in my home dim and the box fans slow down (immediately) whenever the blow-dryer is turned on. Everything is back to normal the instant the blow-dryer is turned off. (My home is about 45 years old with all original electrical AFAIK.)
What is causing the lights to dim and the fans to slow down when the blow-dryer is turned on?
How serious is this problem?
How soon (if ever) does this problem need to be addressed?
Heating coils draw lots of current. Toaster ovens are good examples. Also microwaves (not because of heating coils, though). That current is not available for the lights, and so they dim. It’s not a real problem, unless you blow a fuse (or flip a circuit breaker) all the time. Fixing this is expensive, as it (may) required upgrading your electrical panel and re-wirting at least part of your house.
A blow dryer is a serious user of electricity, as are most devices with heating elements. You are stressing the circuit, possibly overburdening it. A circuit breaker is intended to trip when the allowable current is exceeded. It would probably be a good idea to engage the services of an electrician to be sure the breaker is functional and of the correct rating. If something is wrong, you could cause a fire.
Most modern electricians wire the lights on their own circuit to avoid this problem. It’s also helpful because the lights don’t go out when the wall plug trips a breaker.
I wouldn’t be too worried by a little dimming. Its going to happen when a high wattage device (hair dryer, window AC, coffee pot) is used. If the breaker starts tripping then you will need to possibly get an electrician involved.
I would suggest checking the panel to confirm you have breakers. (small black switches in a row). If you see round glass fuses then call an electrician. Someone may have put in too big of a fuse. Thats a fire hazard.
This is a vintage glass fuse. They are safe unless somebody put in a higher rated one. Usually somebody got irritated because the fuse blew and they put in a bigger rated one. A big fire hazard.
Are you considering any kind of remodel any time soon? If so, that would be a good time to upgrade the panel and do some re-wiring. Based on what you’ve said in the OP, my guess is you have a 100A panel-- the standard today is more like 200A. If you were building your house today, every appliance would be on it’s own circuit, you would have GFI outlets in your kitchen and bathrooms need to be wired with Arc Fault protective wiring.
This isn’t really correct; you make it sound as if only a certain amount of current is available when what actually happens is that voltage drops due to line impedance (not just resistance; for example, transformers will output less voltage than expected due to imperfect coupling; circuit breaker and fuses only limit current by blowing, otherwise, you can pass 20 amps through a 15 amp breaker without tripping it if the duration is short enough).
As for dimming sufficient enough to affect other devices like fans, that does sound excessive; usually only incandescent lights will be affected to any significant degree because they are highly sensitive to voltage changes. Also, when you say “lights in your home” it sounds as if all of the lights dim, not just the ones in the room you are in (in my experience, the only thing that will do this is central A/C when it starts up, but only during start-up).
A certain amount of dimming is normal. Unless your wires are superconductors, they are going to have some losses in them when current flows through them. This causes the voltage to drop, and the lesser voltage causes the lights to get a bit dimmer. It’s normal to see the lights dim a bit whenever you turn on something that draws a lot of power, and hair dryers do draw a lot of power.
They key phrase there though is “a bit”. It sounds like you may be getting an excessive voltage drop which could be a sign of a bad connection somewhere. It’s probably a good idea to have an electrician take a look at it. I can’t tell from a post on the internet how excessive the voltage drop really is and if there is a problem. Someone who knows what they are doing needs to see it.
it would be good to see if you have the correct sized fuses for the wiring.
as stated a dimming when some high current use (when a motor starts or a heater comes on) starts can happen. if it lasts more than two seconds it could be a serious problem.
Nitpick: they’re actually called plug fuses.
As a computer tech, the first thing I thought of was the various electronics that could possibly be in your house that are far more sensitive to voltage irregularities than say a coffee maker or a refrigerator. Cheaply made or sensitive electronics would feel an effect of voltage differences, mainly the ones that are going to be converting A/C current to D/C.
It would personally make me nervous enough to go back to towel drying my head, (even though it’s what I do anyway). Despite the fact that capacitors are on electronics just for the purpose of keeping a steady voltage I’ve seen far too many computers go down where the only logical explanation would be the poor wiring in the condo/apartment/trailer or older house. A UPS would sort things out just fine though or you could always adjust your computer usage likewise so that it doesn’t overlap with your “hair dryer time”.
As for doing extra work on the house, I would think that is something you would have decide based on what money you have on hand and how long you intend to keep living where you are.
There are only three things outside a hair dryer I’ve seen dim lights or more-so slow everything around you. My dad’s 32" tube TV(turning it on), central A/C kicking on and the Dyson vacuum cleaner… if you think about the kinds of things that are making a noticeable difference to our electricity needs you can maybe then compare your own house wiring with that of the hair dryer situation. Slowing the fan in my opinion sounds a bit excessive.
Although voltage fluctuations happen much more than anyone would ever notice, I do believe that they ultimately shorten the life of certain electronics powered by it.
Most, if not all, electronics use a regulated power supply, so voltage fluctuations aren’t going to mean much. In fact, many power supplies are now universal, able to operate over a range like 85-265 volts, even those that aren’t don’t really care if the voltage is 110 volts instead of 120 (most appliances say 110/115 volts because they expect some voltage drop from the “standard” 120 volts). Having designed my own AC/DC power supplies, only a very marginal design will malfunction if the voltage drops by 5-10 percent (the way I design them, I use a ballast to limit current, plus a power resistor for smaller supplies, to reduce the “oops” factor if I accidentally short something or something fails, which also reduces the voltage, ensuring that they will work at reduced voltage).
If the voltage is dropping enough to keep the lights dim and the fan to slow down something else is getting hot somewhere. I would have an electrician try and locate the where the resistance is or like said above possibly too large of a fuse for the circuit.
This is not necessarily true.
The voltage drop may be occurring over a very long run of cable, so nothing may be getting hot.
To Michael, 1) I only wrote what have seen in my experience for the OP to weigh their own situation, not how the electronics are supposed to behave and 2) How reliable is HP and Dell (name a computer brand) in terms of components quality that they use for everyone and the AC/DC power supplies that YOU have built for yourself? I’m sure there’s a quality gap in there somewhere.
Its just that in my experience, surges are more likely to cause damage than voltage sags on the scale of the lights dimming a bit (not full-scale brownouts) from a heavy load (which can be related if the load is inductive, but a simple heating element won’t cause spikes or surges).
Also, for the stuff I build myself, the parts likely came from one of those HP/Dell power supplies since a lot of what I use comes from stuff people throw out (and I do occasionally find that the power supply blew, but often it is fine; the most recent case I can think of was a Compaq computer PSU that failed because the parts used in the standby circuit were undersized (and the main supply probably couldn’t output its rated power either), so not an issue with power quality.
AFAIK it’s only the bathroom lights that dim.
The dimming in my house lasts as long as the blow-dryer is running.
Most likely, the circuit in your bathroom is overloaded, or getting close. A small amount of dimming is normal; a large amount is not. You may need a second circuit or a larger wire size to handle your usual load. In any case, a professional electrician can help, and it might not be expensive if all you need is an upgrade to one room.
It sounds to me like too large of a main fuse or a loose connection right in the fuse box. If you have one of those little thermal lazer temp readers you can shine it around inside your box and look for hot spots indicating resistance.
