Any issue running both MPPTs to the same post on Lynx?

[corn18]

Need to free up a spot on my Lynx. Currently have 2 100/50 MPPTs going to individual posts on the Lynx each using 6 ga wire and a 60A mega fuse. Was going to double them up and use a 125A fuse. Each 6 ga will only carry a max of 50A (max output of the 100/50 MPPT). The outgoing wire to the batts is 2x4/0. Am I missing anything?

 

[justinm001]

You can add a fuse or two to the end of a Lynx. The problem with doing it your way is you really need a fuse that's rated at 1 of the cables not both combined. If one pulls 100a and other 0 it won't blow the 125a fuse.

 

[sunshine_eggo]

The issue is the 125A fuse won't protect the individual wires. If one wire comes loose or fails, 125A won't protect a single 6awg wire.

 

[corn18]

6 ga wire is rated for 120A in free air. 125A fuse would protect the wire effectively, wouldn't it?

 

[sunshine_eggo]

6 ga wire is rated for 120A in free air. 125A fuse would protect the wire effectively, wouldn't it?

If you're using UL1426 or similarly rated wire, then yes, it would be fine.

 

[justinm001]

6 ga wire is rated for 120A in free air. 125A fuse would protect the wire effectively, wouldn't it?

It's not free air there's jacket on the copper wire, what's the temp rating of the jacket and what's that max amperage? If issue your wire will melt the jacket and still flow power until it touches metal and shorts or sets fire.

I think I have 2 mppts wired into 1 port on my Lynx but it's 4ga using 100a fuse and the mppts are 150/100 huge ones with under 2kw solar on each at 48v so 40a is running through them.

 

[corn18]

It's not free air there's jacket on the copper wire, what's the temp rating of the jacket and what's that max amperage? If issue your wire will melt the jacket and still flow power until it touches metal and shorts or sets fire.

I think I have 2 mppts wired into 1 port on my Lynx but it's 4ga using 100a fuse and the mppts are 150/100 huge ones with under 2kw solar on each at 48v so 40a is running through them.

I thought free air in the Blue Sea calculator meant it isn't in an engine room or conduit.

Temp rating is 105 deg C max amps is 115A. I get all my cables from Windy Nation.

 

[justinm001]

I thought free air in the Blue Sea calculator meant it isn't in an engine room or conduit.

Idk don't think so. I assumed it meant free air like copper in free air, such as ground wiring and such where it's fully exposed

 

[corn18]

Idk don't think so. I assumed it meant free air like copper in free air, such as ground wiring and such where it's fully exposed

Seems NEC does not make it very clear, either.

Article 100 Free Air (as applied to conductors).

“Free air” means an open or ventilated environment that allows for heat dissipation and air flow around an installed conductor. Conductors in cablebus are considered to be in free air.

www.electricallicenserenewal.com

 

[justinm001]

Seems NEC does not make it very clear, either.

Article 100 Free Air (as applied to conductors).

“Free air” means an open or ventilated environment that allows for heat dissipation and air flow around an installed conductor. Conductors in cablebus are considered to be in free air.

www.electricallicenserenewal.com

Yeah it doesn't say insulated conductor or anything about the jacketing. Power lines are open air conductors as are heat exchangers and other wiring inside a device.

I'm sure there's a calculator that'll show you how hot 100amps through 6gauge copper wire gets