Voltage and current

[JdoubleU]

I enjoy troubleshooting but lack some knowledge. You all have been great thank you. My question is why when you have a motor that is drawing an excessive amount of current drops the voltage? What is happening hear?

 

[bphgravity]

Let’s look at the situation mathematically.

Let's say you have a 120V circuit that is 500' from the load that operates normally at 5 amperes.

VD = I x R, So:

2A x 1.98-ohms (Table 8) = 3.96 volts dropped

Now, if you increase the load, see what happens to the volts dropped:

5A x 1.98-ohms (Table 8) - 9.90 volts dropped.

While this is a simplified and extreme case, it clearly shows the properties of electricity...

 

[Lxnxjxhx]

Also, motors want a "stiff" voltage source, one that doesn't drop too much when the motor draws more current due to an increase in motor load.
With 1/4 ohm of resistance, a wall outlet is a pretty stiff source, but 100' of #16 extension cord adds a bit more to this resistance.