Where to place the class T fuses and busbars? Boxes, enclosures?

I plan to have my two 4/0 battery cables running from the EG4 server rack in 1-1/2 conduit running to my wireway (and then up to each LV6548 inverter).

My questions are:

1. Where do I place the first 350A class T fuse and fuse holder (I assume within 12 inches of the positive EG4 Rack busbar - so inside the server rack?)
2. Do I put that fuse holder inside some sort of container to pass an inspection? Or do I just put leave the fuse holder laying inside the EG4 server rack enclosure.
3. How about the other bus bars for +/- batteries to each inverter and 200A class T fuses for each inverter. Do these sit inside my wireway, inside a box or something?

Travis55 said:

Where do I place the first 350A class T fuse and fuse holder (I assume within 12 inches of the positive EG4 Rack busbar - so inside the server rack?)

Click to expand...

The closer to the batteries, the better.

I chose to physically bolt my 300A Class T to the top of the busbar in the rack without a holder (there was sufficient room).
I bolted the + cable to the other end of the Class T and came out the top of the rack.
I also used an Adel clamp to ensure the weight of the cable was supported, as you should not put mechanical stress on the Class T.

If you have room for a proper holder in the rack somewhere, I would recommend that over direct bolting.
No idea about inspectors.

Travis55 said:

How about the other bus bars for +/- batteries to each inverter and 200A class T fuses for each inverter. Do these sit inside my wireway, inside a box or something?

Click to expand...

I made a custom box, they need to be accessible in case they blow.
Metal is preferable to plastic, unfortunately mine is plastic.
I also use MEGA 70V fuses on a 600A busbar, but nothing wrong with Class T

Make sure the lengths of DC wire from the busbars to inverters are the same length to balance the DC current.
I also would connect the inverter lugs to be the same distance from the battery feed on the busbars, rather than having the battery at the end.

Inv1+ Batt+ Inv2+

ricardocello said:

I made a custom box, they need to be accessible in case they blow.
Metal is preferable to plastic, unfortunately mine is plastic.
I also use MEGA 70V fuses on a 600A busbar, but nothing wrong with Class T

Click to expand...

Can the bus bars and fuses be in the same box? I was thinking of just grabbing a large metal enclosure, something like 18x18x6 and putting the positive and negative busbars inside, as well as the two 225A class T fuses and fuse holders (for each inverter)

Something like this (excuse the bad drawing! lol)

Travis55 said:

Can the bus bars and fuses be in the same box?

Click to expand...

Mine are in the same box. I think your idea is solid.
The busbars need insulated standoffs from the metal, obviously,

I also like the neat workmanship in your photo, great job.
And your drawing wasn’t half bad either!

Do you plan to add other solar later? if so, plan accordingly in the DC box.

See if others chime in, lots of good ideas this forum.

Travis55 said:

2. Do I put that fuse holder inside some sort of container to pass an inspection? Or do I just put leave the fuse holder laying inside the EG4 server rack enclosure.

Click to expand...

I don't know about inspection requirements. But T-class fuses can be a source of fire, so I'd be inclined to put them in one or more metal boxes, with as little else in them as possible, to protect the house and as much equipment and wiring as you can.

3. How about the other bus bars for +/- batteries to each inverter and 200A class T fuses for each inverter. Do these sit inside my wireway, inside a box or something?

Click to expand...

See above for fuses. I think it's not required, but I'd want at least an insulating cover over the busbars, to prevent horrible shorts if some metal thing being moved or dropped in the area bumps into them. Putting them in the same box with the fuses saves on boxes etc. but might cost if a fuse flames off.

ULR said:

I don't know about inspection requirements. But T-class fuses can be a source of fire, so I'd be inclined to put them in one or more metal boxes, with as little else in them as possible, to protect the house and as much equipment and wiring as you can.

Click to expand...

I've heard of other types of fuses causing a possible ignition source, but class t?

Op, maybe I'm paranoid, but I have a 175amp class t on each battery bank and 300amp on each inverter.

I'm trying to understand how a class T can be a source of fire.
Has anyone that has blown a class T had it blow apart?

I put mine at the top of the box