Filament has an amount of inductance/capacitance. it is very fine coil.
Even piece of wire has finite capacitance and inductnace. Why do you
think there is a surge current when light bulb is turn on? Ever heard of
phase compensating capacitor or lump inductor. Or go inside a power room
in any big commercial building, what do you see there? Do you know why
electric cable is some times criss crossed or twisted?
Simply to answer your question, Yes, really, always. It becomes very
critical on high frequency. Todays florescent bulbs are driven by 44KHz
current. Pure resistive circuit in real world is problably near none.
Z^2 is combination of R and j(Xl-Xc). Remember HS physics class?
Xl and Xc cancels each other, equal value, whatever left is either Xl,
or Xc. In real world most load is inductive. In inductive circuit
voltage is leading and current is lagging. This phase difference
produces wasted power which does not do any work. Ideally the phase
difference should be zero.
That is why KVA is not equal to Watt rating of a device.(efficiency)
I spent my working life on RF telecommunication(mobile and fixed base),
UPS, MG, Antenna farm, stuff like that.
There is usually a black wire connected to the circuit breaker. If you can
clamp around that wire with the appropriate ammeter (Google clamp-on
ammeter) you can measure the current in that circuit.
What are you trying to accomplish?
I have an adaptor for my ammeter that I can plug into an ordinary wall
receptacle. It has a loop on it to clamp around and I can plug an appliance
into it to see what the load is for that appliance. I think Amprobe makes
On Tue, 20 Feb 2007 18:30:25 -0500, "John Grabowski"
I'm using a Kill-A-Watt meter for that now, but previously I had a VOM
attachment for that. I made it from a remote control cord (just a
switch at one end) with the switch removed and replaced with banana
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