# Difference between L1 and L2

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Solar Expert Posts: 259 ✭✭
Is there a Difference between L1 and L2 that is measurable?

In other words, is there a way to distinguish between the L1 line and the L2 line or are they just designated like that because there are 2 lines.

• Banned Posts: 17,615 ✭✭✭
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Re: Difference between L1 and L2

The difference between L1 and L2 is 240 Volts.
Sorry, but that's exactly what it means.

Line 1 and Line 2 are the two 'hots' of a 240 (or 230) Volt AC feed. In North America (and other places where the power standard is used) it is split in the middle with a Neutral line which is tied to Earth ground (so that it has zero Voltage potential in respect to ground). This give the split-phase system. L1 to N is 120 VAC, L2 to N is 120 VAC. These will be 180 degrees out of phase: when L1 reads 'X' Volts positive in respect to Neutral L2 will read 'X' Volts negative in respect to Neutral.

For the most part they are interchangeable as far as usage goes.
• Solar Expert Posts: 95
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Re: Difference between L1 and L2

Caribocoot is correct. The one thing I would add is its determined by the installer. Once its run its done.

Chuck
• Solar Expert Posts: 259 ✭✭
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Re: Difference between L1 and L2

Got it!

Yes I understand the voltage difference b/w L1 and neutral and L2 and neutral as well as L1 & L2.

I meant when it comes time to connect an inverter to the mains panel. The inverter has clearly marked L1 and L2. But the mains panel doesn't. So I wondered if there was a precise way of pairing InverterL1 to XMainsPanel and InverterL2 to YMainsPanel.

Theoretically there is a difference because when one phase is "up" the other is "down", correct?

But does it make a difference when connecting them?
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Re: Difference between L1 and L2
quique wrote: »
Got it!

Yes I understand the voltage difference b/w L1 and neutral and L2 and neutral as well as L1 & L2.

I meant when it comes time to connect an inverter to the mains panel. The inverter has clearly marked L1 and L2. But the mains panel doesn't. So I wondered if there was a precise way of pairing InverterL1 to XMainsPanel and InverterL2 to YMainsPanel.

Theoretically there is a difference because when one phase is "up" the other is "down", correct?

But does it make a difference when connecting them?

The difference is at the source of the power. After that it doesn't matter. Loads are either connected between one Line and Neutral or between the two Lines. Other than Neutral being bonded to ground AC has no 'polarity' in the same sense as DC.

BTW it doesn't matter for GTI connections either, as the inverter will 'shift' its output to be in sync with the utility power phase.
• Solar Expert Posts: 259 ✭✭
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Re: Difference between L1 and L2

Right! That's what I thought. I remember one the main functions of the grid tied inverter is precisely to "sync" with the power grid...