1. Where does 120/240 volts come from?

2. Transformer on the Utility Pole 3 wires to your residence

3. Where does 120/240 volts come from? This wire is ‘center-tapped’ at the transformer winding and is known as the ‘N’ – Neutral.

4. Where does 120/240 volts come from? This ‘N’ wire is also connected to ‘EARTH.’

5. Where does 120/240 volts come from? This wire is electrically ‘H’ – HOT.’ This wire is electrically ‘H’ – HOT.’

6. Where does 120/240 volts come from? 120 v

7. Where does 120/240 volts come from? 120 v ? v

8. Where does 120/240 volts come from? 120 v

9. Where does 120/240 volts come from? 120 v ? v

10. Where does 120/240 volts come from? 120 v 240 v

11. Where does 120/240 volts come from? ? v

12. Where does 120/240 volts come from? 0 v

13. Where does 120/240 volts come from? ? v

14. Where does 120/240 volts come from? 120 v

15. Where does 120/240 volts come from? 120 v This wire is ‘H’ and you will get electrocuted if you come in contact with it.

16. Where does 120/240 volts come from? ? v

17. Where does 120/240 volts come from? 120 v

18. Where does 120/240 volts come from? 120 v This wire is ‘H’ and you will get electrocuted if you come in contact with it.

19. Where does 120/240 volts come from? This wire is labeled as ‘L1.’

20. Where does 120/240 volts come from? This wire is labeled as ‘L1.’ This wire is labeled as ‘N.’

21. Where does 120/240 volts come from? This wire is labeled as ‘L1.’ This wire is labeled as ‘L2.’ This wire is labeled as ‘N.’

22. Where does 120/240 volts come from? This wire is labeled as ‘L1.’ This wire is labeled as ‘L2.’ This wire is labeled as ‘N.’ This wire is labeled as ‘G.’

23. Where does 120/240 volts come from? This wire is labeled as ‘L1.’ This wire is labeled as ‘L2.’ This wire is labeled as ‘N.’ This wire is labeled as ‘G.’ Note that ‘EARTH’ ground is the ‘reference’ for our electrical systems.

24. Where does 120/240 volts come from? L1 – N = ? v. L2 N L1 L2 – N = ? v. L1 – L2 = ? v.

25. Where does 120/240 volts come from? L1 – N = 120 v. L2 N L1 L2 – N = ? v. L1 – L2 = ? v.

26. Where does 120/240 volts come from? L1 – N = 120 v. L2 N L1 L2 – N = 120 v. L1 – L2 = ? v.

27. Where does 120/240 volts come from? L1 – N = 120 v. L2 N L1 L2 – N = 120 v. L1 – L2 = 240 v.

28. Where does 120/240 volts come from? According to the NEC, National Electric Code, when there is a three wire circuit (L1/N/L2) there are two hots and one neutral.

29. Where does 120/240 volts come from? BUT, also according to the NEC, National Electric Code since 1987, when there are two wires, there CANNOT be a NEUTRAL.

30. Where does 120/240 volts come from? So what is the identification of two wires with a NEUTRAL? L1(H) – L2 Since L1 is marked ‘H’ or hot, it is hot. And since L2 is not marked ‘H’ it is not hot, therefore it is NEUTRAL and it cannot be labeled as ‘N’ since there are only two wires.

31. Where does 120/240 volts come from? So what is the identification of two hot wires? L1 – L2 Since neither L1 nor L2 are marked as ‘H’ or hot, they are both ‘H.’

32. Where does 120/240 volts come from? Go to page A2 in your Student Handout Packet and checkout the ID (identification) on the disconnects in the upper right corner of the page.