Enphase Combiner box neutral size

[JoeNorm]

I am using the enphase branded combiner box for an enphase system. It houses the monitoring device which requires a neutral.

My question is about the size of this neutral. As far as I know it is only being used for one thing, the electronics inside the box. So am i allowed to downsize it to a 14awg wire since the controls circuit is is 15amp?

That would mean if I am backfeeding, say 50 amps to the main panel I would run my two larger L1+L2 with a smaller neutral. Is this allowed?

I am sure there is a code section on this, thanks

 

[ggunn]

I am using the enphase branded combiner box for an enphase system. It houses the monitoring device which requires a neutral.

My question is about the size of this neutral. As far as I know it is only being used for one thing, the electronics inside the box. So am i allowed to downsize it to a 14awg wire since the controls circuit is is 15amp?

That would mean if I am backfeeding, say 50 amps to the main panel I would run my two larger L1+L2 with a smaller neutral. Is this allowed?

I am sure there is a code section on this, thanks

You can only make it as small as the EGC.

 

[jaggedben]

I think it's allowed, with ggunn's clarification, even though I've seen so many full size neutrals run.

See 220.61 and 215.2(B).

 

[JoeNorm]

Thanks, that's good to know. For my last job I had to drill a 10" concrete wall and then do a feeder tap so I was interested in the smallest volume setup I could get away with. Most of the time it is less critical.

 

[ING23]

By the way , and talking about neutral and Enphase System , Any one know how The microinverters will feed a house load of 120 Volt without going to the neighborhood transformer, How current flow knowing from the Roof there is no neutral just 240 V?

 

[ggunn]

By the way , and talking about neutral and Enphase System , Any one know how The microinverters will feed a house load of 120 Volt without going to the neighborhood transformer, How current flow knowing from the Roof there is no neutral just 240 V?

If the inverters are grid tied they are connected to the neighborhood transformer. In the absence of any export limitations, which direction the current flows through the transformer depends on the loading on the secondary.

 

[wwhitney]

By the way , and talking about neutral and Enphase System , Any one know how The microinverters will feed a house load of 120 Volt without going to the neighborhood transformer

They can't, the house loads depend on the utility transformer for the unbalanced portion of the 120/240V loading that ends up on the neutral.

Cheers, Wayne

 

[Zee]

I have also only used a neutral size=EGC.
If the broader question is how small of a conduit can you get away with, remember the Consumption CT coil wiring! I usually connect the 2 twisted pairs with WAGOs to a communication cable (like for ethernet).

 

[jaggedben]

By the way , and talking about neutral and Enphase System , Any one know how The microinverters will feed a house load of 120 Volt without going to the neighborhood transformer, How current flow knowing from the Roof there is no neutral just 240 V?

For a grid tied system, the neighborhood transformer is necessary as Wayne said.

For systems that go off-grid with the Enphase System Controller, that is why they have an autotransformer in the System Controller to derive the 120V.

 

[ING23]

Thanks for yours replay