Receptacles per circuit?

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Jim W in Tampa said:
How do you figure that ?And what about lights? I agree many use very little but right now on master bedroom circuit 2 computers ,1 tv, dvr box ,few lights are on.Still far under 1800 watts.
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Move to MN, then you could add a space heater :)

But seriously, all it takes is someone putting a space heater and 1500w blow dryer on the same circuit to exceed 1800w. The things in my bedroom total about 3000w (very large computer, lots of lights, shredder, space heater) when they are all running full-tilt boogie. Fortunately it's not a single branch circuit or I'd be miserable come winter ...
 
Correct me if I am wrong but I have always figured the load in regards to wattage as 100 watts = 1 amp and figure that at 80 % of the total.This just in a general lighting/receptacle load,just a quick in the head calculation to get in the ball park figure.So if you have a 3,000 watt load on a circuit it will be right around 24 amps or so_Or am I missing something.
 
allenwayne said:
Correct me if I am wrong but I have always figured the load in regards to wattage as 100 watts = 1 amp and figure that at 80 % of the total.This just in a general lighting/receptacle load,just a quick in the head calculation to get in the ball park figure.So if you have a 3,000 watt load on a circuit it will be right around 24 amps or so_Or am I missing something.
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I assume you're asking me since I mentioned 3,000w.

I use 120v for wattage, not 100. So my guess is that it's something like 25A between the two circuits that feed my bedroom. One of the circuits, which goes on to feed the bathroom lights, has the space heater on it. That circuit is just plain WRONG because so far as I can tell there are also 8 x 75w floods on that same circuit, in addition to the space heater and bathroom lights (6 x 40w). I really need to map out the entire house some day. The panel directory has scribble marks through several entries and some of the re-scribbling doesn't make sense.

Moving the space heater probably wouldn't hurt ...

(Edited to add ....)

... except there's no place in my bedroom to move it because the rest of the outlets are on the same BC as the computer, shredder and a few odds and ends. What I need is to move the floods off that circuit or add another 20A BC to my bedroom.
 
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Jim W in Tampa said:
How do you figure that ?And what about lights? I agree many use very little but right now on master bedroom circuit 2 computers ,1 tv, dvr box ,few lights are on.Still far under 1800 watts.
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i'm just saying if people didn't jamb the bed leg against the receptacle I don't think arc faults would even be required, Why do we need to protect the dumb people? If they want to run an extension cord under the carpet than WTF? and what if that extension cord had a ground and was NOT a flat cable would it trip on OC? or would you still need that arc fault breaker?
 
stickboy1375 said:
Why do we need to protect the dumb people?
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Because dumb people vote, and they have friends and family members who vote.

stickboy1375 said:
. . . and what if that extension cord had a ground and was NOT a flat cable would it trip on OC? or would you still need that arc fault breaker?
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It could have enough leakage current to heat up the surrounding materials, and not have enough current to trip the OCPD.
 
iwire said:
Where is the 'General Discussions' section?

What I mean is this forum IMO is set up more for code talk than discussing which method is better or worse.

.
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Bob you bring things here that are far from code discussion at times and no one is telling you to go to the 'General Discussions ' section ......

I think that general discussions remark is arrogant and smart ass talk!!!
 
drg said:
Bob you bring things here that are far from code discussion at times and no one is telling you to go to the 'General Discussions ' section ......

I think that general discussions remark is arrogant and smart ass talk!!!
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Be carefull he could deleet you.
 
Regardless of how many circuits you install, if more current is drawn than is permitted by the size of the overcurrent device, the overcurrent device will open.

There are many homes that are wired with the minimum number of devices and circuits. The occupants learn how to deal with it, or they hire someone to install additional circuits... it has been a large portion of this industry for as long as I can remember.

It is not to say that you can do just the minimum... if you so choose to do more, great.

But the NEC is minimum and it is permitted to work in that fashion. In the Northeast where I inspect, I see the different styles everyday, I always approve the minimum installations...remember there are some who want new homes and cannot afford the top dollar others are able to pay.
Lets not keep some from their American Dream.
 
charlie b said:
It could have enough leakage current to heat up the surrounding materials, and not have enough current to trip the OCPD.
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Not so much leakage current, but arc temperature. An arc can be a heck of a lot hotter than a dead short with the same current. Arc welding doesn't work by melting the weld metal through a short, it works by keeping an arc lit between the tip of the rod and the place where the weld metal is being deposited. I used to cut through plate steel with 200A, a copper-clad carbon gouging rod, and a oxygen hose. If I'd taken the welding lead and clamped it to the plate I was cutting, I'd have had to wait a Really Long Time for that piece of steel to get hot. But strike an arc, turn on the O2, and burn, baby, burn. I've turned steel into a shimmering pool of molten metal with as little as 60A.

And that's why arcs are so dangerous.
 
tallgirl said:
I've turned steel into a shimmering pool of molten metal with as little as 60A.
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No doubt.

Unfortunately the present AFCIs don't see arcs less than 70 amps so they do not protect the typical appliance cords that we where told they could.

But not to worry now they say the next generation will be much better. ;)
 
I recently refed my Dad's barn, where he does most of his workworking. He has a lot of tools, and some of them pull a lot. I convinced him to let me install a new feeder, because the voltage drop on his was pretty bad.

This week, I've been building a tack room inside my horse barn, to get these %&#%& saddles out of my office, because I stub my toe every time I get on the forum. He came out to give me a hand.

The air compressor was running, and he started the table saw, and heard the air compressor bog way down, and about busted a gut.

"So let me get this straight. You tell me I need to spend hundreds of dollars to get my barn refed because of voltage drop, and your barn can't handle two motors at the same time?"

Darn right. All I needed for my barn was a circuit for lights and the occasional cord-and-plug appliance. I'm never out there, and have sparse lighting requirements. Different projects have different considerations. That doesn't make the minimum trash. :)
 
iwire said:
No doubt.

Unfortunately the present AFCIs don't see arcs less than 70 amps so they do not protect the typical appliance cords that we where told they could.

But not to worry now they say the next generation will be much better. ;)
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I've read several of the patent filings and I don't understand why they DON'T work better than y'all say they do.

The basic electrical pieces-parts seem like they should work -- measure dI / dt (change in current with respect to time) and if it doesn't agree with what it should be based on a purely resistive load, or a reasonable inductive load, or something like that, generate a trip signal which opens the breaker.
 
tallgirl said:
The basic electrical pieces-parts seem like they should work -- measure dI / dt (change in current with respect to time) and if it doesn't agree with what it should be based on a purely resistive load, or a reasonable inductive load, or something like that, generate a trip signal which opens the breaker.
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Than you should go and work for the manufactures because apparently they need you. :)

As it stands today the 2008 NEC will require a product that literally does not exist for sale.

(BTW you may be forgetting that many electrical devices produce series arcs as part of their SOP, having an AFCI trip every time a vacuum motor starts or you flip on a switch is kind of a downer)
 
iwire said:
Than you should go and work for the manufactures because apparently they need you. :)
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Well, I doubt that -- the patent filings say all the right stuff, but I don't understand the waveforms that a "bad" arc would generate well enough to tell a microprocessor how to separate the "good" ones from the "bad" ones.

The person they most likely need to hire is Jeff. My education is mechanical engineering and software engineering. I understand the physics behind detecting an arc, I just don't know what to do with it!

Apropos switch and motor produced arcs, the filings talk about looking at how often the arcs are generated, and so on. The filings read a bit like software patents which tells me that they've got the detectors working properly, they just don't know how to program the tiny computer (or PGA or whatever) they are shoving into each circuit breaker. As I read things, an arc that's not reproduced for more than a half cycle doesn't count as an arc.
 
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Joeseph, Stickboy is right, the 180 va is for other than dwelling units.

Roger
 
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