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abracadabra · 02-10-2010, 07:28 PM

edit see below

abracadabra · 02-10-2010, 07:30 PM

Quote:

Originally Posted by CodeRage

Since the voltage is rated at RMS saying the current is continuous peak at I RMS is perfectly acceptable...

RMS or Root Mean Square is the average electrical power. Current rises and falls as the voltage rises and falls.

It may be considered accetable but it's factually incorrect.

Cpt_Kirks · 02-10-2010, 07:43 PM

Maybe I am just a spendthrift, but to me, my little white hiney is worth the $20 I spent on a 20A GFCI.

Hermit · 02-10-2010, 07:53 PM

Quote:

Originally Posted by abracadabra

Speaking of misconceptions "30+ amps of continuous peak current"

240v AC (Alternating Current ) goes from 0v to 120v back to 0v then to 120v in the opposite direction or polarity for a total swing of 240v. The current goes up and down with the voltage and the electrons changes the direction in which they flow as the voltage changes polarity.

DC (Direct Current) can offer a continuous peak current.

Or you'd need something like 3 phase AC to be close to a continuous peak current condition.

Residential electricity is single phase AC.

Been a while, but since it is RMS isn't PEAK for 120 around 177 or so? Long time since I did the calculations....

**IrregularPulse** · 02-11-2010, 12:21 PM

Quote:

Originally Posted by mhermetz

I could do that.... Think I would be able to roll out the copper tube without weakening or causes kinks? I assume you have to do that to make the CFC

I used my old IC. I uncoiled it, fed it through the hose, the recoiled it for my CFC. So far so good.

**passedpawn** · 02-11-2010, 01:13 PM

Quote:

Originally Posted by abracadabra

RMS or Root Mean Square is the average electrical power. Current rises and falls as the voltage rises and falls.

It may be considered acceptable but it's factually incorrect.

Wrong, sorry. RMS values are not the same as "average" values for sine waves. The RMS value is the DC equivalent, so it is the perfect way to know the heating potential or work potential of AC power.
RMS is not only an acceptable way of describing AC electricity, it is the standard way in which most AC components are rated.

abracadabra · 02-11-2010, 02:21 PM

http://en.wikipedia.org/wiki/Root_mean_square#Relationship_to_the_arithmetic_me an_and_the_standard_deviation

below is a quote from the web page listed at the top of this post.

"So, the RMS value, IRMS, of the function I(t) is the constant signal that yields the same average power dissipation". Where (t) equals time.

Perhaps in trying to explain this in laymans terms I over simplified. But if you'll read the web page at the top of this post you'll see RMS is indeed average power.

And yes RMS is an expression of what average continuous power would be if it was actually continuous but since it is not it is merely expressed in a calculation as if it was continuous.

sparkyaber · 02-11-2010, 03:20 PM

Quote:

Originally Posted by Jknapp

Interesting situation happened at work, that sorta applies to the Murphy's Law/GFCI thing..

On a job site, a extension cord (we call em stingers) was plugged into a 20amp GFCI outlet on a 20A circuit. A tech mistakely cut the plugged-in extension cord with his linemans pliers. POP! After making sure he was okay, we went to reset the GFCI - but it wasn't tripped. Went to the panel & the 20a breaker was what tripped.

Hmm. The GFCI was wired correctly: wires to panel feed the Line side. GFCI tests fine.

Our theory: as his pliers cut through the 12/3 cord, his cutter first severed the hot & ground first, cutting the neutal after the panel breaker popped. That's our theory, but in any case the GFCI, which is supposed to be sensitive, didn't do anything.

Anyway, moral of the story: Things sometimes don't go the way we want or expect. GFCI's are great things, even if they don't ALWAYS provide protection. Oh, and Murphy's Law is always in effect.

Nobody explained this to you so: GFCI detects a leak of current- They do not protect against short circuits. That is the breakers job. This played out exactly as was supposed to. Your theory maybe correct as the gfci monitors the current between the hot and neutral.

**CodeRage** · 02-11-2010, 03:27 PM

Quote:

Originally Posted by sparkyaber

Nobody explained this to you so: GFCI detects a leak of current- They do not protect against short circuits. That is the breakers job. This played out exactly as was supposed to. Your theory maybe correct as the gfci monitors the current between the hot and neutral.

Huh?

If when he had cut the cord and he bridged 110 and neutral ONLY and was 100% insulated the gfci would not have popped but the breaker would have.

Had he made contact with ground and 110 first or if he himself started to conduct current to ground, the gfci would have popped.

When you press the test button on a gfci, it leaks current from the line to ground.

kryolla · 02-11-2010, 03:48 PM

I didn't read through all this but my take on it is that GFCI does work. I had a saltwater reef tank plugged into an external GFCI/extenstion cord. I was hooking up my new lights and the whole thing fell into the tank, my first reaction was to grab it then I realize what I was doing and pulled my hand out. The GFCI popped and I didn't feel a thing so I am a firm believer in GFCI. I did have to buy a new ballast.