ECN Forum Forums Technical Discussion Electrical Theory and Applications LOOPS IN BOX

OK, Here's a few numbers on the coiled wire thingee mentioned in this thread:

For purposes of keeping things simpler, I'll use values from an one-inch air core, with multiple stacked layers. If we were to use the 2" wire coils wrapped one after another, this would create a single-layer coil, from which a tremendously long length would be needed in order to develope enough X [Reactance].
So on to the figures!! Yippee!!

For a perfect layer coil, using 1" air core:
X [total Reactance] = 1.2 Ohms for 100 amps @ 120 VAC.
L [Inductance, in milli henrys "mh"] for 1.2 Ohms X = <4.0 mh - so I'll use the rounded figure of 4.0 mh

4.0 mh winding calcs for 1" perfect layer air-core coil = 20 wraps [winds], 30 layers [stacks].

These figures are only FYIs and "What-if's", since the high amperage flowing in the 4 mh coil with 120 VAC applied, will create such a high heat, there will be quite a bit more X involved from the added Resistance and Inductance. That might drop the total I down to 80 amps.

Lastly, the perfect layer calcs use varnished conductors for tight proximities in the windings and layers. Insulated conductors might affect the overall winding calc.
Also, the larger size of conductors required to pass >80 amps continuous would alter the total calc. All alterations would influence the calcs to require more windings than shown here.

Scott SET

Interesting, its common practice when building motor control panels to loop the L leads to the motor starter for ease of amperage checks using a clamp on, it also makes a neat installation. Never heard of any reasons why NOT to do this.

I don't see a reason not to make a loop now and then either.

1" diameter would be a pretty tight turn for heavy wire and even if you are making 1" loops, you aren't making 600 of them in the same wire.

Scott's didn't tell you the values for a single 2" loop. But suffice it to say that it is probably comparable to having one parallel wire an inch longer than the other and no one that I know ever worries about that.

But there's a thought, folks. If you take about 1500 miles of wire and unroll it and connect both ends to the same terminal, you would have a dead short (with 60 Hz AC).

Actually, I think you might have a really bad "short" with just one end connected to the line.