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Is it possible to overload or short circuit a fuse with too much HT gear?

post #1 of 28
12/25/12 at 11:32pm
Thread Starter 
So tonight I was watching a movie on my projector, and had a few other things plugged into a few sockets. My PC and projector were plugged into a power bar, and all connections were tight. Had a space heater on, and microwave was being used. PC speakers were plugged into a nearby outlet by itself. My PS3 was off and was also plugged into the power bar.

All of a sudden everything shuts off, and I have tried unplugging and plugging things back in, turning things on and off, and switching placements in the outlet--all to no avail. eek.gif


I turned on some lights and they worked, and some lights didn't turn on. 3 outlets, on the other side of my basement suite work... so is this a serious house electrical problem. The landlord who lives upstairs is on vacation and won't be home until January 1st, so I have no idea how serious this is. I am 99% sure all their electrical stuff will work, and assume everything will work when she arrives.

For the time being, I am afraid to use my projector which shut off without turning off the lens which made me very mad mad.gif, since this is the most costly thing I own and times are a bit tough for me recently, so replacing or repairing is impossible now. Oh, and the fact I may overload or short circuit the 3 outlets I have that still work confused.gif


Lastly, I am afraid how costly the repairs are for this electrical stuff and scared when I get my AVR back from the repair shop. Why? If the fuse box/breaker can't handle this, I'm assuming it can't support a receiver, Hi-Fi bookshelfs, a 10" subwoofer, and a PS3 ontop of my projector. frown.gif


So I implore you AVS Forums, what is the severity of this problem and should I be worried about setting up my HT once I have my AVR back?
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post #2 of 28
12/26/12 at 8:40am
It really just depends on how the wiring is set up in the space you are using. First, is your electrical service on a breaker system or a fuse system? Most modern panels are breakers which trip automatically when there is an overload on the circuit and can be reset once the overload situation is resolved. On a fuse panel the fuse has to be physically replaced with a new fuse.

The maximum safe load on the circuit should be calculated based on 80% of the capacity. Thus a 15 amp circuit should have a load max of 12 amps or 1440 watts.To determine the wattage, you take the voltage times the amperage. That information should be listed on each of your devices you are plugging in. By looking in the panel to determine which breaker tripped or fuse blew you should be able to determine how many amps that circuit is rated for.

Take into consideration that items like electric space heaters can have a very high load at startup and while running. I would guess that having the space heater on the same circuit as the rest of your equipment may be the culprit in this case. A lot of those types of heaters can draw 1500 watts or more. So for 1500 watts you are looking at using 12.5 amps on that circuit just for the heater.

If you have 3 outlets that are currently working then I would say move the space heater to one of those as it is most likely a separate circuit feeding those 3 outlets. However, keep in mind this may not be the only device tripping your current circuit.
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post #3 of 28
12/26/12 at 9:59am
I'm sure that space heater and microwave running together were the culprits. Do you have access to the fuse box? I couldn't tell from your post. Maybe you just need to flip the tripped switches. I would suggest you get a battery backup so that your projector stays on in these cases. And if you are going to run the microwave, turn off the space heater until you are done. Otherwise basic ht gear shouldn't overload most circuits.
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post #4 of 28
12/26/12 at 11:30am
Thread Starter 
Unfortunately I'm not a homeowner so an electrician can't come over because of this (landlord is gone on holidays). Anyways, I have a circuit breaker and not a fuse. I looked at the box and more or less, each switch is already labeled. The weird thing is, most of those are for upstairs and maybe 2 are for my basement but those aren't labeled.

But my guess it's the combo of the microwave and heater. Heater was set to max, and it is labeled as going to 1750 or 1500 watts. Microwave was likely a 700 watt model as it's smaller in size.

Aye, so I will keep that in mind in the future.
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post #5 of 28
12/26/12 at 12:23pm
Any of those switches pointing opposite of all the others or have red showing that it is tripped?
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post #6 of 28
12/26/12 at 4:52pm
Thread Starter 
There are absolutely no lights or bulbs/indicators, and all the switches are physical and are pointed towards "On". None of these switches are pointed to the opposite end (which would be 'off' but this isn't labeled).

*Sigh*, I guess the good news is likely, nothing serious happened and all that really needs to be done is resetting the switches.

The ones for the basement suite have "15" on both switches, and no "On" or "Off" label. These breaker switches look different from the rest, and are all black, while the other ones are black and blue. Guess I should not chance it, and just wait till she returns from her vacation. I am tempted to use the working outlets for my speakers, PC and projector... but I won't, lol
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post #7 of 28
12/26/12 at 4:59pm
http://www.dummies.com/how-to/content/how-to-reset-a-circuit-breaker.html
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post #8 of 28
12/26/12 at 5:14pm
Quote:
Originally Posted by jautor View Post

http://www.dummies.com/how-to/content/how-to-reset-a-circuit-breaker.html

haha. I really dont see what is so hard about this. Not trying to be rude, but you really need to learn how to reset your breaker for cases like these or for an emergency. Learn where the water shut off valve is while you are at it.
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post #9 of 28
12/26/12 at 5:19pm
Some circuit breakers are difficult to tell if their tripped. The handle still points to ON but it's tripped internally. A simple way to fix is to turn each one off and back on. If tripped this will reset it. Worst case you will have a few clocks to reset.

Alternatively if you bend the toggle towards OFF slightly you can sometimes also tell if it's tripped. A breaker that is on will have some spring resistance towards OFF. A tripped breaker will feel soggy.

In your case I would just reset them all. This is a whole lot cheaper than an electrician house call for $100 and perfectly safe.
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post #10 of 28
12/26/12 at 5:28pm
Quote:
Originally Posted by Glimmie View Post

A simple way to fix is to turn each one off and back on.

Exactly
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post #11 of 28
12/26/12 at 6:10pm
Quote:
In your case I would just reset them all. This is a whole lot cheaper than an electrician house call for $100 and perfectly safe.


It wouldn't be wise to reset the breakers for the landlord's apartment. I would just toggle the basement switches.
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post #12 of 28
12/27/12 at 5:39am
Quote:
Originally Posted by Sonyad View Post

It wouldn't be wise to reset the breakers for the landlord's apartment. I would just toggle the basement switches.

Really? Why is that? Will he get evicted for make her reset her clocks?
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post #13 of 28
12/27/12 at 1:12pm
Quote:
Originally Posted by Sonyad View Post

It wouldn't be wise to reset the breakers for the landlord's apartment. I would just toggle the basement switches.

So there was a utility power glitch while she was away. Can't say that doesn't regularly happen.
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post #14 of 28
12/27/12 at 1:38pm
Just flip every breaker off and back on again until everything is restored to normal. As others have said.

You simply had too much on the circuit. It's designed to trip at 80% of it's rated load to prevent burning your house down. There will be no damage done. Just put things back to normal and try not to run the microwave and space heater at the same time.
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post #15 of 28
12/27/12 at 7:49pm
Thread Starter 
Hi guys, so I finally flipped the tripped up switch, and yes, I know it was a dumb question. Really was never taught or shown any of this when I was a kid tongue.gif

Didn't really understand what one should look like, and after jautor posted the Dummies.com link, I knew exactly what all those terms meant as those images look identical to the breaker we have. Now, I feel a helluva lot better since everything works normally again, and all the outlets for my appliances have current. Now I know what to do for future reference!!

THANK YOU so much jautor and everyone else! biggrin.gif:D:D

Now, I hope my projector isn't messed as this is a second instance where power was shut off abruptly while my Epson was running a movie.
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post #16 of 28
12/27/12 at 8:23pm
Quote:
Originally Posted by Louquid View Post

It's designed to trip at 80% of it's rated load to prevent burning your house down.
No, properly functioning breakers will run forever at their rated amperage. How fast they will trip after that depends on how much over the rated current you go. A little over and it will take hours to trip. A lot over and it will trip almost instantaneously.
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post #17 of 28
12/27/12 at 8:24pm
Quote:
Originally Posted by BestInTheWorld View Post

Now, I hope my projector isn't messed as this is a second instance where power was shut off abruptly while my Epson was running a movie.
Don't sweat it. The need to let the fan run for a while when powering down is highly over hyped.
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post #18 of 28
12/27/12 at 9:35pm
Quote:
Originally Posted by BestInTheWorld View Post

THANK YOU so much jautor and everyone else! biggrin.gif:D:D

No problem, and as Pain suggested, do find out where your main water shutoff valve is, too - that's the other important "emergency" homeowner item to know about.
Quote:
Now, I hope my projector isn't messed as this is a second instance where power was shut off abruptly while my Epson was running a movie.

As Colm said, not a big deal - much worse would have been unplugging it, then immediately turning it back on (a "hot strike"). A long cool down without a fan probably didn't do much, if any, damage to the bulb's lifespan... And that's all we're talking about - lamp life.

Jeff
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post #19 of 28
12/28/12 at 12:58pm
Thread Starter 
Quote:
Originally Posted by jautor View Post

No problem, and as Pain suggested, do find out where your main water shutoff valve is, too - that's the other important "emergency" homeowner item to know about.

As Colm said, not a big deal - much worse would have been unplugging it, then immediately turning it back on (a "hot strike"). A long cool down without a fan probably didn't do much, if any, damage to the bulb's lifespan... And that's all we're talking about - lamp life.
Jeff

I will find out where the main shut off valve is, guess that will eventually come up at least once in my life.

Alright, as long as my Epson runs fine I'm all good. How much of the lamp life is affected would you say, in terms of hours? If I had say 1000 hours left before this happened, how much reduced life am I looking at here (roughly)?
Quote:
Originally Posted by Colm View Post

Don't sweat it. The need to let the fan run for a while when powering down is highly over hyped.

As long as the expensive lens and the expensive components aren't affected, I'm happy smile.gif
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post #20 of 28
12/28/12 at 1:07pm
Quote:
Originally Posted by BestInTheWorld View Post

I will find out where the main shut off valve is, guess that will eventually come up at least once in my life.
Alright, as long as my Epson runs fine I'm all good. How much of the lamp life is affected would you say, in terms of hours? If I had say 1000 hours left before this happened, how much reduced life am I looking at here (roughly)?
As long as the expensive lens and the expensive components aren't affected, I'm happy smile.gif
Hard to say about the lamp. Could be a little, could be a lot, but probably not at all. If you did that all the time I could see it maybe becoming a problem but you are fine. Don't stress over it. Having the breaker trip is no problem compaired to a power surge. If you had a power surge you would have something to worry about.
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post #21 of 28
12/28/12 at 2:33pm
Quote:
Originally Posted by Colm View Post

No, properly functioning breakers will run forever at their rated amperage. How fast they will trip after that depends on how much over the rated current you go. A little over and it will take hours to trip. A lot over and it will trip almost instantaneously.

That's inaccurate. The trip curve of a breaker depends on more than just theorized current load.
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post #22 of 28
12/28/12 at 10:48pm
Quote:
Originally Posted by Louquid View Post

That's inaccurate. The trip curve of a breaker depends on more than just theorized current load.
Oh, it is accurate enough as far as it goes. Of course, you may have to rerate the breaker depending on ambient temperature. And practically it is really not forever at rated current, just a real long time because enough heat will probably build up sooner or later to cause a thermal trip. In any case, the point is that breakers are not designed to trip at 80% of their rating, and in general how long it takes for the typical household breaker to trip depends on the overload. For example a Square D QO 15A breaker could take as long as 90 seconds to trip at a 50% overload, and much longer for a lesser overload, but will trip instantaneously at 7 times the rated current, at standard temperature.

Was there something besides ambient temperature you were thinking about?
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post #23 of 28
12/29/12 at 8:39am
Quote:
Originally Posted by Colm View Post

Oh, it is accurate enough as far as it goes. Of course, you may have to rerate the breaker depending on ambient temperature. And practically it is really not forever at rated current, just a real long time because enough heat will probably build up sooner or later to cause a thermal trip. In any case, the point is that breakers are not designed to trip at 80% of their rating, and in general how long it takes for the typical household breaker to trip depends on the overload. For example a Square D QO 15A breaker could take as long as 90 seconds to trip at a 50% overload, and much longer for a lesser overload, but will trip instantaneously at 7 times the rated current, at standard temperature.
Was there something besides ambient temperature you were thinking about?

Agreed

Quote:
Originally Posted by Louquid View Post

That's inaccurate. The trip curve of a breaker depends on more than just theorized current load.

Please explain
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post #24 of 28
12/29/12 at 10:00am
Continuous and non-continuous current loads are two different things. Most small breakers are not designed to operate at 100% continuous load, because of the unpredictability of the non-continous current load. The current rating of most electric appliances only deal with continuous loads.

An appliance with a run load of 15A would not run forever on a 15A breaker. Depending on what this appliance is, the actual current could be higher or lower than it's rated run load for short periods of time. Typically when current is varying a certain percentage above the rated load of the breaker, it falls back under rated load before the breaker is designed to trip. (Breaker trip schemes are a huge part of R&D.) But this isn't always the case. Continuous run loads above 80% of the breaker's trip rating can, and usually do, have spurious trips because the current was at a percent overload for longer than the breaker was designed to handle.

So yes, in theory a 15A load should easily run forever on a 15A breaker with ideal ambient temperatures. But current will never be perfect and will always vary. Because of this, it's advised to stick with the 80% rule. (Which seems pretty arbitrary. But is considered a safe bet for all/most small breakers.)
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post #25 of 28
12/29/12 at 3:57pm
Quote:
Originally Posted by Louquid View Post

...it's advised to stick with the 80% rule.
Yes, there are a number of 80% rules in the NEC, which is where this oft misinterpreted number comes from. But breakers are not designed to trip at 80% of their rating.
Edited by Colm - 12/29/12 at 4:09pm
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post #26 of 28
12/29/12 at 4:25pm
neither are fuses or overloads. Overloads especially because they are set to a specific amp rating such as .95A.
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post #27 of 28
12/29/12 at 4:55pm
The NEC is all about "minimum" standards.

While manufactureres don't "design" their breakers to trip at 80% of it's rated load, they are fully aware of the nature of current. They suggest oversizing small breakers because that is what practical applications call for.

Inrush current can far exceed "7 times the rated current".
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post #28 of 28
12/29/12 at 5:38pm
Quote:
Originally Posted by Louquid View Post

The NEC is all about "minimum" standards.
Well, it is about what is considered adequate for fire and electrocution safety. You can always exceed the standard. So what?
Quote:
Inrush current can far exceed "7 times the rated current".
In which case the named breaker will trip magnetically. So what? Obviously you have to select the right breaker for the application.

FWIW your previous posts were informative. Now, you seem to be taking things out of context and arguing just for the sake of arguing. If you want to continue, enjoy yourself. I won't be responding.
Edited by Colm - 12/29/12 at 5:51pm
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