Con-fused 70Amp Mega fuses don't exist, now what?

[chaostactics]

I need a fuse for my Victron 100|50 where it connects to the Lyxn distributor via 6AWG. As I understand what I'd want is a 70A fuse. I can only find 70A in AMI/MIDI I can find 80A and 60A mega fuse. What's the best option?

It's 600 W of panels in parallel with a

2 Pole 1000V 63 Amp Isolator between the panels and the MPPT.​

 

[HighTechLab]

I'd use a 60a. Megafuses can handle 100% of their rating continuously without blowing.

EDIT: Even if you used the 80a fuse, it'd be safe and would perform fine...but there is a debate below about using yet, an even bigger 100A fuse, but I think it's absolutely foolish to use such an overkill fuse size since you only need to handle 50A continuous, and it's much better to be safe rather than sorry.

NEC says the next higher overcurrent device rating (above the ampacity of the device or conductor being protected) shall be permitted to be used 240.3(B), however if you read below, someone thinks that it's OK to go nearly 150% beyond the manufacturer's recommendation, which is 2 sizes larger than what is required.

At the end of the day, the electrical codes applied are a bare minimum requirement for safety, not a design criteria or installation manual. You make the call, it's your burden to explain to insurance company why the fuse never blew and the thing burned to the ground...because you followed someone's advice online.

My $.02, for what it's worth.

 

[Supervstech]

I need a fuse for my Victron 100|50 where it connects to the Lyxn distributor via 6AWG. As I understand what I'd want is a 70A fuse. I can only find 70A in AMI/MIDI I can find 80A and 60A mega fuse. What's the best option?

It's 600 W of panels in parallel with a

2 Pole 1000V 63 Amp Isolator between the panels and the MPPT.​

I’d want more information before recommending a option.
How many panels do you have?
What voltage are they operating?
What voltage is the scc providing to the batteries?
What type of batteries are you using?

 

[John Frum]

@Supervstech deleted this twice now because he thinks its dangerous electrical advice.
What is the danger @Supervstech?

For the busbar fuse on the Solar charge controller branch circuit I would use a 100 amp fuse to protect the 6 awg wire.
6 awg pure copper wire with 90C insulation in free air is good for 100 amps.
The fuse protects the wire.
The solar charge controller has its own internal midi fuse directly off its own positive terminal.

 

[Supervstech]

@Supervstech deleted this twice now because he thinks its dangerous electrical advice.
What is the danger @Supervstech?

For the busbar fuse on the Solar charge controller branch circuit I would use a 100 amp fuse to protect the 6 awg wire.
6 awg pure copper wire in free air is good for 100 amps.
The fuse protects the wire.
The solar charge controller has its own internal midi fuse directly off its own positive terminal.

No, I only deleted the post once, and asked you not to repost a third time without knowing what the OP has in his setup.
As I said to you in the warning I issued to you, the site owner deleted your posts because HE and other members felt the advice was unsafe and needed qualifiers at a minimum…

The wiring connected to the charge controller wouldn’t be in free air, now would it?

Are you confident without any first hand knowledge of the OP setup that your advice is completely safe and sound?

 

[John Frum]

No, I only deleted the post once, and asked you not to repost a third time without knowing what the OP has in his setup.

My mistake

As I said to you in the warning I issued to you, the site owner deleted your posts because HE and other members felt the advice was unsafe and needed qualifiers at a minimum…

The wiring connected to the charge controller wouldn’t be in free air, now would it?

I specified in free air.

Are you confident without any first hand knowledge of the OP setup that your advice is completely safe and sound?

If its in free air yes.
I'm not in the habit of giving knowingly bad advice.

 

[Supervstech]

My mistake

I specified in free air.

If its in free air yes.
I'm not in the habit of giving knowingly bad advice.

Free air means ALL portions of the wire are in free air. If the OP specifically stated the wire needing fused is in a distributer… so, NOT all in free air…

 

[John Frum]

Free air means ALL portions of the wire are in free air. If the OP specifically stated the wire needing fused is in a distributer… so, NOT all in free air…

Given that 4/0 awg is the practical upper limit on wire size that goes into a lynx branch position.
You could not terminate 400 fuse amp branch circuits on a lynx distributor/power-in.
Is that how you see it?

 

[Supervstech]

Given that 4/0 awg is the practical upper limit on wire size that goes into a lynx branch position.
You could not terminate 300 or 400 amp branch circuits on a lynx distributor/power-in.
Is that how you see it?

 

[John Frum]

View attachment 133269

That table is for free air which you seem to have said does not apply to wires terminated on a lynx distributor.

 

[Supervstech]

That table is for free air which you seem to have said does not apply to wires terminated on a lynx distributor.

The table has three qualifiers… are you certain all three qualifiers meet the OP situation?

 

[John Frum]

The table has three qualifiers… are you certain all three qualifiers meet the OP situation?

Since this is a 12 volt mobile system NEC rules don't necessarily apply.

Interactive Wire Size Calculator

Battery Chargers, Inverters, Solar Components, and Wiring Supplies for Boats, RVs, and Off-Grid Applications.

baymarinesupply.com

 

[Bud Martin]

What does 'Coverd' mean?

 

[John Frum]

The topo is here.

What wiring configuration do I need? First-time solar install.

I'm trying to finalize supplies so I can get help installing, and I also want to learn more so I'm not useless during installation. This is the diagram I'm following. I've also attached a pic of the inverter terminals. The debate is if I need 10/3 or 10/2 and 6/3 or 6/2 X/3 = 3 load wires and...

diysolarforum.com

Its an explorist life drawing and he designs to ABYC standards.

 

[John Frum]

What does 'Coverd' mean?

It means insulated.

 

[Bud Martin]

It means insulated.

Do you mean insulated with some kind of insulation material, I.E. Silicone?
So per charge, it show 'Bare' 4AWG has 155 A, but with 'Covered' it is rated at 163 A.
How can it be higher when 'Covered' and it also does not have the type and rating of the insulator?

 

[John Frum]

Do you mean insulated with some kind of insulation material, I.E. Silicone?

Some kind of insulation not sure what kind.

So per charge, it show 'Bare' 4AWG has 155 A, but with 'Covered' it is rated at 163 A.
How can it be higher when 'Covered' and it also does not have the type and rating of the insulator?

Seem counter-intuitive.
Maybe covered doesn't mean what I think it means.
Good eyes as usual @Bud Martin

 

[Bud Martin]

View attachment 133269

Can you please provide the link to that chart? Thanks.
It does not look right that 'Bare' wire has lower Amp rating than the 'Covered' wire.

 

[John Frum]

@Bud Martin I believe this is the table.

Ampacities of Bare or Covered Conductors in Free Air | UpCodes

Explore a searchable database of US construction and building code. Code regulations are consolidated by state and city for easier navigation.

up.codes

There is a button that allows you to see the relevant chapter for context.

 

[John Frum]

Found this

Chapter 1 General: General, Illinois Electrical Code 2020 | UpCodes

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes