Hi Scott:
The cause of the neutral-earth voltage is the neutral current times the neutral resisitance to the point where the neutral is connected to earth. The higher the neutral current, the higher the voltage difference between the neutral and earth conductors. Building power distribution systems are designed for no more than 6% (typical 3%) voltage drop to the outlet. This drop is evenly divided between the Line/Live conductor and the neutral conductor. So, this means the voltage drop on each conductor is no more than 3% (1.5% typical). So, for a 120-volt system at full load (15 amps or 20 amps), the neutral voltage should be no more than 3% of 120 V or 3.6 V (1.8 V typical). For a 230-volt system at full load (16 amps), the neutral voltage should be no more than 3% of 230 V, or 6.9 V (3.45 V typical). As the system ages, the resistances of the various connections will increase, thus increasing the neutral- earth voltage. You mileage may vary. Best wishes for the holiday season, Rich --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
