Re: [RE-wrenches] fusing requirement for 4 strings run to a Inverter with 2 MPPT's

That document refers to 2008 NEC 690.9 code which has the exemption that is used for grounded inverters. Section 690.35 for ungrounded systems just refers back to 690.9 for over-current protection. So I do not see any indication that two strings on an ungrounded inverter could not have the same

Re: [RE-wrenches] fusing requirement for 4 strings run to a Inverter with 2 MPPT's

Hi Dan Can you provide any documentation on this? Thanks Jay Peltz power. Sent from my iPhone > On Jan 28, 2016, at 8:52 PM, > wrote: > > While Brian T. is correct that fusing is not required for string-to-string > overcurrent

Re: [RE-wrenches] fusing requirement for 4 strings run to a Inverter with 2 MPPT's

While Brian T.  is correct that fusing is not required for string-to-string overcurrent protection with two strings into two channels, there is another reason to require fusing. Transformerless inverters like Fronius Primo have no transformer to provide AC-DC isolation, so a ground fault can allow

Re: [RE-wrenches] fusing requirement for 4 strings run to a Inverter with 2 MPPT's

Al, As long as you only have a max of two strings going into each of the separate MPPT channels, no string fusing is needed. So with four strings, two on each MPPT input channel in the inverter, no string fusing is needed. This is one of the big advantages to having multiple MPPT channels in GT

Re: [RE-wrenches] fusing requirement for 4 strings run to a Inverter with 2 MPPT's

Hi Al, My understanding of dual mppt inverters is that they are treated nearly as two inverters on the DC side. The requirement for fusing on multi string arrays has to do with the reverse flow of current in the event of a fault on one of the strings. 2 strings are safe, 3 or more and you can

Re: [RE-wrenches] fusing requirement for 4 strings run to a Inverter with 2 MPPT's

Regarding the primo we just installed 5 at a location and used the midnite with the switch, (mnpv6 disco) its the only way on this inverter to perform any testing. With all the issues it helped out a great deal. Jerry On Jan 27, 2016 4:09 AM, "Allen Frishman" wrote: >

[RE-wrenches] fusing requirement for 4 strings run to a Inverter with 2 MPPT's

Wrenchers, What is the requirement for fusing 2 strings per MPPT? Specifically for an inverter like the Fronius Primo that has no integrated fuses.If you run 2 strings to each MPPT do you need to fuse each string?In this case there is a total of 4 strings which would need to be