Class T fuse holder termination - I think I screwed up.

[ricardocello]

Conduit ampacity is derated, which makes sense, but is that with multiple conductors?
If you put a single welding wire in a 1” conduit, does the derating apply?
Do conduit fill rules apply, meaning 1.5” conduit is necessary for a single conductor?
Only if over 24” maximum nipple length?

 

[robbob2112]

Conduit ampacity is derated, which makes sense, but is that with multiple conductors?
If you put a single welding wire in a 1” conduit, does the derating apply?
Only if over 24” maximum nipple length?

There are rules about how many of what size you can put inside a conduit and the size conduit you have to use. I am not sure if they cover the sheath types because welding wire for instance is much thicker than THHN so it would take a size or two up either way.

And I know there are deratings based on if the conduit is on a roof, open air, side of building, or buried.

 

[ricardocello]

I like my welding wire hanging free, the way nature intended.
Though conduit would make it neat and tidy.

 

[robbob2112]

I like my welding wire hanging free, the way nature intended.
Though conduit would make it neat and tidy.

Well, seems like the rules are for it to be in metalic conduit if it is inside a building. That can be the flexible kind or rigid.

If I read the Mike Holt reference for solar wiring the Pos and Neg should be in a minimal twist around each other. But conduit rules say wires go in straight with no twists ... I wonder which one rules.... probably the straight ... Or they need to be in a raceway and then you can twist them.

The twist or running them together eliminates/reduces a magnetic buzz and interferance in devices.

Twisting reduces inductance and apparent resistance to the inverter when connected - ... interesting reading.... Downside is it makes it larger and requires more length to start with... AND twisting verse just being close to each other the difference in EMI is mininal..

Might be a good topic for one of our members with access to an EMI lab to look at... I know there are a few.

More research to do on that topic.

Either way they should at minimum be run side by side the length of where they go verse draped loosely apart.

 

[SparkyJJO]

Well, seems like the rules are for it to be in metalic conduit if it is inside a building. That can be the flexible kind or rigid.

If I read the Mike Holt reference for solar wiring the Pos and Neg should be in a minimal twist around each other. But conduit rules say wires go in straight with no twists ... I wonder which one rules.... probably the straight ... Or they need to be in a raceway and then you can twist them.

More research to do on that topic.

Are those rules for conduit for the PV wires only, or also the battery wires though? PV wires can be really high voltage, but battery really high amperage...

 

[ricardocello]

I have a big rolling 19” rack with inverters and mppts, and busbars.
I have a separate 19” rack with batteries.
The two are connected by about 6 feet of 4/0 Class K welding wire (+,-) and a chassis ground 2/0.

As my setup is “temporary”, because it can roll right out the door, conduit for the welding wire is not an option for me.

 

[robbob2112]

Are those rules for conduit for the PV wires only, or also the battery wires though? PV wires can be really high voltage, but battery really high amperage...

They are for high current DC wires. So with PV wires I wouldn't thing it matters except they can be long runs. Higher voltage would mean less current and I would have to look up which makes an antenna radiate more RF. But without changing like AC or a modulated signal I would wild guess it doesn't matter.

My takeaway so far from reading is just lay your large high current battery wires together as in side by side and you will take care of this.

If I come up with something different I'll post back.

 

[gotbeans]

Regarding ferrules and 2/0 wires, the ferrules are very thin and are one time use just to keep the fine strands from being outside of the connection and arcing. Just slip it over the wire and it will compress down when tightened.
But you need proper copper lugs to carry the amperage. And a reminder to all: fine stranded welding wire is EPDM rubber coated and kind of meant to be used in environments where the wire is on the floor of a business coming into contact with oils, grease or other shop used compounds in the welding process.

The most appropriate battery wire to use is fine stranded THHN/THHW which will bend and be able to pass through conduits easily.

EPDM handles more heat and is just as flexible so it really doesn't matter, at least as far as the points you made go.

The main difference THHN travels in conduit better is because it's gloss finished so it slides.

 

[Hedges]

Conduit ampacity is derated, which makes sense, but is that with multiple conductors?
If you put a single welding wire in a 1” conduit, does the derating apply?
Do conduit fill rules apply, meaning 1.5” conduit is necessary for a single conductor?
Only if over 24” maximum nipple length?

Conduit adds thermal insulation. SMA recommends not to use PVC conduit for battery cables (but I'm sure it would be OK at low enough current vs. cross-section.)
Seems to me one wire in metal conduit wouldn't have the same heat buildup as multiple, but it still doesn't have air passing over its insulation. Would be limited to convection within the conduit, so I'd expect it to run hotter.

If you have 3 wires in a conduit, it is very difficult to pull around corners is 3x wire diameter > conduit ID because they wedge.
Not sure the rules, but if I could fit 1 conductor in a conduit I'd use it.

All my battery cables are exposed, but maybe code requires either conduit or restricted access, not sure.

 

[Hedges]

They are for high current DC wires. So with PV wires I wouldn't thing it matters except they can be long runs. Higher voltage would mean less current and I would have to look up which makes an antenna radiate more RF. But without changing like AC or a modulated signal I would wild guess it doesn't matter.

A loop of wire radiates based on AC current through it and loop area.

A single wire over ground plane, or a pair of wires with separation, radiates based on AC voltage.

Feeding a capacitor, PV array feeds relatively steady voltage and current. But can have common-mode voltage imposed on it, acts like a single wire over ground plane and acts as an E-field (voltage) antenna. To the extent it has current flowing through capacitance to ground, B-field (current) antenna. Return path of ground wire from PV frames back to inverter, routed together with PV+/-, should kill its performance as an antenna.

 

[robbob2112]

I do know the NEC requires any DC wires inside a building to be in metal conduit, this goes for PV wires, cables between batteries and inverters, or any others. Not sure if there is a cutout for the low amp signal wires but I am sure there is.

Also no AC carrying wires in the same conduit or raceway as DC wires.

 

[SparkyJJO]

I do know the NEC requires any DC wires inside a building to be in metal conduit, this goes for PV wires, cables between batteries and inverters, or any others. Not sure if there is a cutout for the low amp signal wires but I am sure there is.

Also no AC carrying wires in the same conduit or raceway as DC wires.

Dang it, now I need to put my phone charger cable in a conduit...

 

[JRH]

I have 250A Littelfuse fuses. Same ones that the Blue Sea holders use. Shouldn't be a problem.

Yep , the 250amp fit the larger holder ( 225 to 400 amp)

The slightly smaller holder fits the 110- 200amp…

J.

 

[robbob2112]

Yep , the 250amp fit the larger holder ( 225 to 400 amp)

The slightly smaller holder fits the 110- 200amp…

J.

The blue sea ignition protected ones (with the latches on the cover) fit either size fuse, but they cost more.
I was wrong

 

[JRH]

The blue sea ignition protected ones (with the latches on the cover) fit either size fuse, but they cost more.

That’s a new one from what I understand … it makes a ton of sence , but I haven’t seen it… I have 9 of the other ones 5502 and 5007…..the smaller ones with the latch are much easier to open and close than the larger ones… Both are excellent but the new one wasn’t available when I bought mine a couple of years ago…

It is possible they have consolidated the two into one holder… so people won’t get the two mixed up… I don’t know but will call on that soon.

I have to get a few more this summer for new stuff I’m adding and for spares…and that will be what I get whatever they are doing…

Isn’t that just the way life works… no matter what you buy , or how thorough you try to be , somthing new crashes the party and makes you have to re-vamp you plan…

J.

 

[Zwy]

No, thanks!
But would you buy from shunts.com again? I’m looking for reliable no-fuss vendors.

Don Rowe

 

[Brucey]

https://www.amazon.com/gp/product/B001VJ03LA

This is what should be used. Very secure, stable and allows easy replacement of a blown fuse.

Should one get the ignition protected version? Less risk if an LFP cells starts venting hydrogen?

 

[robbob2112]

The ignition protected one will get hotter since it only has small slits for ventilation. The other if mounted vertically will shed heat pretty well.

But, taking the fuse covers off the non-ignition version is a royal PITA, I personally would always get the latch covered ones.

 

[ChrisG]

Should one get the ignition protected version? Less risk if an LFP cells starts venting hydrogen?

I’m sorry, still laughing at this snarky one. Almost thought I wrote it

 

[Brucey]

I’m sorry, still laughing at this snarky one. Almost thought I wrote it

I don't have a boat but it seems the ignition protected one will contain the class T and prevent any arcing within the enclosure from propogating externally?