Fire Risk? Advice Appreciated!

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  #1  
Old 08-15-07, 12:57 AM
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Fire Risk? Advice Appreciated!

I live in an apartment and within the last year they sent in an electrician to install a whole new circuit breaker box and circuits (the old one was very old and a fire risk). When this guy rewired everything, he twisted so many things into 1 particular circuit; I find myself challenged about how to offload some of these electronics I use, to lessen the load on that breaker so I do not start a fire in here.

Recently I bought a new home theater Receiver and Subwoofer for my living room. However, the living walls are part of the overloaded circuit (covers 2 rooms and 3 walls all on same circuit.)

The closest wall outlet that is on a circuit all by itself (no other appliances/electronics or ceiling lights are attached to this outlet and its breaker. However its a good distance away.

So, I want to use this receiver that is a 6.2 amp item when fully under load. It would be ideal for it to be on its own circuit breaker to have some elbow room. Since i can't modify anything myself or hire an electrician to do a job for me since I live in an apartment my only option is .... the doomed!... extension cord.

I know there are risks associated with extension cords, however i bought an extremely high quality one, a Coleman Cable 12/3 100-Foot, contractor grade. Its a 12 gauge wire capable of handling 125V and 15 amps, used for outdoor electric mowers and heavy tools. I only need about 75 feet to run the cord along the edges of the wall into the next room to get to this open outlet... but I can only buy 50 or 100 foot lengths.

This is the cord I bought here:
http://www.amazon.com/gp/product/B00004SQFD/105-3226635-0676458

>>So, the question is... I want to know how much a fire risk this is?

Things I know not to do with this extension cord:
-Don't overload it (and I wont 1x 6.2amp item only)
-Don't do sharp bends on it, cause they wear out and cause a fire
-Don't put it under carpet (i wont this will be sitting above)
-Don't use extension cords permanently (I will use this over time, but I will turn off the receiver once a day for 8 hour+ period, so the load will be less)

I am not asking for permission or a green light to make a foolish mistake here, everyone is free and clear. I am asking for educated guesstimates on the level of safety I will be able to have doing this.

Thanks in advance.
 
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Old 08-15-07, 04:56 AM
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Welcome to the forums. At least you realize you can't make modifications in the apartment's infrastructure. Just because there are circuits tied together in the breaker panel, doesn't automatically mean the circuit is overloaded. What gives you the indication it is overloaded? Has it tripped more than once in a day?
Advice on using the extension cord. Don't. Extension cords, no matter the size are credited with more fires than in-wall wiring.
If these circuits can be separated in the breaker panel, you may can ask the landlord to have them separated into another breaker to reduce the load to the particular area you need to use the most.
 
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Old 08-15-07, 05:28 AM
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If I were going to use an extension cord, I would use one that is just the right size for the job and would not require figuring out what to do with 25 feet of excess cord.
 
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Old 08-15-07, 05:42 AM
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Is the ciruit shared with other apartments? If not, you can determine the total load you'll be pulling by adding up the wattages of each device you'll use on a particular circuit and dividing the total by the voltage.

For example, a 100 watt light bulb, a 400 watt computer, a 120 watt VGA monitor, and your 750* watt surround sound system = 1370 watts. Divided by 120 volts = just under 12 amps. Keep in mind that you can only load a circuit to 80% of its ampacity = 1920 watts at 120 volts on a 20a circuit.

* 750 watts (actually 744) is the power consumption of a 6.2 amp device at 120 volts. Note that this is electrical power and not the amplifier power to the speakers. Also, unless you regularly run the stereo at full volume, it will never get close to 6.2 amps.

Sound science warning!: If the stereo runs the speakers at 100dB Sound Pressure Level (SPL) at full power, it will be WAY too loud to listen to for an extended time. Normal loud listening levels are 90dB in a living room. That's 10dB under the max. For every 3dB reduction, the power is divided in half. -10dB halves it three times. If you started with 750 watts (electrical draw) at full volume, you're now down to less than 100 watts. There is a certain amount of idle current the system will draw even when it's muted, but it's negligible compared to full volume.
 
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Old 08-15-07, 06:32 AM
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Ty for feedback all... and thx for the welcome to the forums. This seems like a forum and I like to call myself a DIY kinda person, but usually for electronics and carpentry.

To answer some questions here:
I have added up all the amps currently loaded on the circuit. That breaker is also tied into 3 ceiling lights. Overall currently its no more then I would want to do safely. To add a 6.2 amp receiver and a 2.2 amp sub woofer thats just to much to tack onto the same circuit. I am just trying to keep the load under 15 amps (mostly cause the old breakers were rated at 15 amps and the new ones they put in were 20 amps... so this seems stupidly dangerous to me... so i am trying to avoid going over 15.. in fact I'd like to observe that "80% load" rule if I can and only go 80% of 15 amps.

I cant install this setup elsewhere in the apartment or I would. Getting the land lord to pony up cash to tweak my circuit breaker isn't going to happen. They already did this once this year (and i noticed my rent was raised this go around along with it.)

Lastly, no I don't share this with other residents (neighbors). However, what I meant about 2 rooms and 3 walls was...that 1 circuit breaker has 5 outlets and 3 ceiling lights all connected to the same breaker. One of those rooms is the living room so it has a lot of things plugged in. I am trying my best to divide out the electronics in here best I can. However, these new additions are just to much on that circuit.

----

So I will ask this. If a extension cord is rated for 15 amps and I will only put 6.2 amps on. Why is this a danger at all? There may be some fundamental information I may be missing here not being an electrician.

To my understanding a Fire gets produced only by the following things:

A fray in the wire can cause a short and the wire load goes up and over heats and starts a fire. As long as the wire doesn't get cut.. or bent at sharp angles as to produce wearing on the wire this probably will not happen.

People use extension cords not rated to handle the load they are using it for and again the wire overheats.

PS:
I'm very well versed on my V, A and W formula conversions its how I know how many amps I am running now. However its hard to say just how much a load you are getting just like you said if you run at 1/2 volume its not max amp draw... which is why last week I bought a Kill A Watt Meter from amazon.
http://www.amazon.com/P3-International-Kill-Electricity-Monitor/dp/B00009MDBU

The Kill-A-Watt meter comes in the mail today. I will be able to get a very accurate gauge on whats going on in here and not just adding the "specs" value of everything together. Its a meter you plug into the outlet.. so obviously only measures the load at the outlet and not in the circuit like ceiling lights and such. But, this will be somewhat more helpful to me on getting a litmus test on where things stand now.. and just how much a load I get on the circuit.
 
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Old 08-15-07, 08:32 AM
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You are correct in that the biggest problem with the use of extension cords is because of heat. Heat is generated by the current flowing through the wires. That heat must dissipate, and it does so through the cord insulation and through the air and other material surrounding the cord. Problems happen for a variety of reasons. Among them: the wire size is too small for the load; the cord is routed through walls or under carpets; the cord is damaged; the cord is too long.

Other problems also exist with extension cords. Sometimes these problems lead to some of the previously mentioned situations. The biggest issue here is the cord itself. People want to hide it, either for aesthetics or because they don't want to trip over it. This means they route it through walls or under carpets or bend it very tightly around corners.

My concern with your setup is that you are using a cord that is too long. This increases voltage drop, which is never a good thing, but sometimes is tolerable. Will your voltage drop be tolerable? Maybe, maybe not. What are you doing with the extra 24 feet of cord? If you stretch it out then you further increase the possibility that it gets in the way. If you wind it up then you create electromagnetic radiation where it is wound. This increases the lost power and can cause interference with nearby electronics.

As I said before, the distance is what I am concerned about. As such, I refer you back to my earlier post, which I have copied below.

If I were going to use an extension cord, I would use one that is just the right size for the job and would not require figuring out what to do with 25 feet of excess cord.
 
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Old 08-15-07, 08:44 AM
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Couple of things. First, you mention that the old circuit breakers were 15 amp and they've been upped to 20. This could be allowed, if the original wire was 12 gauge. If you can see some of the jacketing in the receptacles or load center, it would tell you. If not, then the electrician should have defaulted to 15 amp. I would be suspect of the rest of the job if this wasn't the case.

Unfortunately, as a renter, you are subject to what the landlord is willing to do for you. It sounds like you'd prefer to own so you'd have control over these issues. I don't think the landlord would be responsible to make any further changes to the wiring unless you can prove that the work wasn't done with permits, wasn't done properly, or the electrician wasn't certified to do this work. But for the fact you're saying you went from 15 to 20, I'd probably side with the landlord on this one. It doesn't sound too terribly unsafe and from your username I tend to believe you have the golden ear thing. But aside from that, you are safer not using a 75' extension cord.
 
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Old 08-15-07, 09:03 AM
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Smile

If your receptacles and switches (throughout the house) have the wires "backstabbed" into them I would definitely re-locate them to the side screws (if available) or replace them with quality receptacles where the wire can be attached to the side screw or perhaps into the back behind a pressure plate that can be tightened by tightening the side screw.
 
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Old 08-15-07, 09:10 AM
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> that 1 circuit breaker has 5 outlets and 3 ceiling lights all connected
> to the same breaker.

This is actually fewer than you would find in most general purpose circuits like living rooms and bedrooms. Code allows a figure of 3 watts per square foot for general purpose circuits. This means that a 15A (1800W) circuit can service about 600 sq. ft. of living room space. General purpose circuits are not subject to the 80% rule unless you know that everything will be turned on max for >3 hours at a time (which would make the load continuous, not general purpose).

I personally believe it would be safer to use the in-wall wiring rather than an extension cord. In addition to the electrical risk described by others, the extension cord also presents a tripping hazard.
 
  #10  
Old 08-15-07, 10:54 AM
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Everyone I want to thank you thoroughly for giving me in depth and logical reasoning as for for why I shouldn't run the extension cord.

As I mentioned, I received that Kill A Watt meter not to long ago in the mail today. I tested my current main setup plus items on other side of the wall. I am amazed at how much lower the amp usage is then I was calculating. I suppose I should have realized when I read the specs of electronics I cant always assume the amp value they give as the value that item normally runs at through normal use; but, rather the maximum load it will have under heaviest use of all features/volume/etc cranked to max. It looks like at maximum I will be around 13-14 amps on the odd occasions and more likely 10-12 amps more frequently. (with this new receiver/sub)

This meter has me feeling a lot more confident now about adding this receiver/sub to the room. I will most likely get a smaller 6 foot extension cord and move my PS3 and Xbox 360 to another circuit in same room (different breaker) It has other items on that breaker. However, it seems I have elbow room on that breaker to off load a couple more amps off my heavy circuit.

Does anyone here own that "Kill A Watt" meter I mentioned? If so can anyone vouch for its accuracy? I'd hate to be getting a false sense of confidence. It seems like a nice little device, I will be running around this place for the next week test power consumption details on all my stuff.

http://www.p3international.com/products/special/P4400/P4400-CE.html
There website says 0.2% accuracy.
 
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Old 08-15-07, 01:34 PM
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> Does anyone here own that "Kill A Watt" meter I mentioned?

Yes, and I recommend it; cheap and effective.
 
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Old 08-15-07, 05:10 PM
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Used mine on refrigerator testing other day: 152 watts of run and 455w defrost cycle. Then used KWH setting to determine if power flow was interrupted when I went to lunch during the run test of compressor and when I returned in about 1 hour+ I confirmed at (.2 KWH @152 watts ), by math, that it did not shut off on thermal or any other reason. I can't live without this 'tool' now.
 
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Old 08-15-07, 05:43 PM
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Just opinion but maybe the main point has been missed. Breakers prevent fire hazards...usually. If the breakers aren't tripping and are sized for the wires that are attached you don't have a fire hazard. Use the outlets if the breakers trip then worry but don't try to over think it and perhaps create a less safe situation with an extension cord.
 
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Old 08-16-07, 04:43 AM
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"I suppose I should have realized when I read the specs of electronics I cant always assume the amp value they give ... "
That was my point about the 6.2 amp audio system: You can't use the fuse rating for your calculations. The fuse or breaker is rated for 6.2 amps because that's the point at which damage will occur to the electronics inside the device. My TV, for example, has a 3 amp fuse, but the wattage number is only 140.

Out of curiosity, what did the Kill-A-Watt read from your stereo?
 
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Old 08-16-07, 06:10 AM
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I am waiting until Friday for my speaker cables to come from Monoprice.com (great company btw if no one here has used them, "monster cable" quality at extreme discounts prices.. quick delivery and good service, I highly recommend them for wires and cables)

Until i get those cables I wont know what the normal speaker volume load on that receiver will be. Currently I purchased a 5.1 speaker setup and the receiver is capable of 7.1 for the Dolby True HD decoding. I know after I get these other 2 speakers the load will increase even further.

Specs wise, its a 7 channel by 100w receiver.

>>Rick Johnston: "Out of curiosity, what did the Kill-A-Watt read from your stereo?"

Sorry Rick, When I made that comment yesterday (about partial load) I was concuring with you and did not make that clear. When i turn the receiver on and keep it idle (just HDMI video processing only) its a 0.56 amp load. I wont know the full story until I get those cables and put the amplifier under a load. (same for sub woofer)

>>ray2047: "Use the outlets if the breakers trip then worry but don't try to over think it and perhaps create a less safe situation with an extension cord."

I agree with not being paranoid and creating a more risky fire situation. However, I will try to explain why I am being paranoid about this situation.

Some of these reasons I don't want to push the boundaries of 20 amp breaker, is because I doubt the credentials that person had. They were just a maintenance person of the building. (They could be certified, I did not ask) I spoke to them during the whole installation and they seem quite knowledgeable, however I am still suspect of their ability when they upped a 40 year old buildings 15 amp breaker to a 20 amp breaker and shoved so many cables onto one breaker and left 1 breaker useless inside the box. This all seems suspect to me.. hard to tell. (I realize a few of you have mentioned that these could all fall safely under acceptable code)

However, on a hunch, I figure I will play it safe and treat the situation like it used to be when I 1st moved in and only work with a 15 amp ceiling. My fear is if the gauge of the wall wiring is not up to 20 amp code. I wont even trip the breakers by the time the wires create a fire.

=====

I will keep everyone posted as this progresses I just wall mounted the speakers yesterday. I am going to thoroughly test every outlet in that living room tonight with the meter. I should be able to get an accurate forecast of what I can move around in there or rethink what has to be done before the official full fledged test on Friday.

Just so everyone knows, I appreciate you all discouraging me from using that extension cord. I hope amazon.com will accept a full return that is by far the most expensive extension cord I have personally bought. (nice quality though)
 
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Old 08-16-07, 07:15 AM
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You really do need to determine if he used 20 amp breakers with #14 wire. If you can't easily do that I'd suggest you pay a licensed electrician to check that 20 amp breakers haven't been used on #14 wire.
 
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Old 08-16-07, 08:59 AM
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I may flip the juice off to a socket today and see if its 12 gauge wire or what.
 
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Old 08-16-07, 09:12 AM
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Yes, #14 wire may have a breaker no larger than 15A; and #12 wire may have a breaker no larger than 20A.
 
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Old 08-18-07, 07:30 AM
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Just wanted everyone to know my project went well.. and no incident. I am dropping a line back to thank everyone for their time and advice. The receiver+sub came in at about 1/2 the amps its rated for.. running at about 1/2 maximum volume (most likely loudest I will ever take it)

This is more then within my 80% rule of 15 amps.. even with everything I currently had plugged in.
 
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