ABYC definition of “conduit”

[team karst]

Originally Posted by wyb2

I wonder what the flame rating of my plywood bulkheads is?

Thats why u dont want flaming wiring pieces tied to it. [emoji106]

[boatpoker]

Can't you use an MRBF fuse instead ?

[s/v Jedi]

Originally Posted by wyb2

Sorry about your head.

Amazon is the wild west of product descriptions. Even without knowing that polyethylene would be a problem here (I hadn’t thought about it), I would have given it a 50/50 chance of getting the material correct. You basically just have to rely on the fact that no one is setting up a separate production run for something like that to sell on Amazon.

It’s not a perfect system , I definitely got copper clad aluminum wire once when it clearly stated solid copper.

Looks like the same stuff from McMaster is listed as “polyester fabric”, and you can get it as ‘standard’, VW-1 flame rated, or NFPA 262 plenum rated. My guess is the Amazon stuff is exactly the same as the ‘standard’ stuff from Mcmaster.

You do bring up a good point. In the future I’ll probably opt for the VW-1 stuff from McMaster, looks like it’s a very small extra cost. The plenum rated stuff is a 5x the price, might take my chances and pass on that.

https://www.mcmaster.com/9196K14

I wonder what the flame rating of my plywood bulkheads is?

Better rethink that… that sleeve is not split, the stuff is h@ll, I have been haunted by it, no more for me

[s/v Jedi]

The temperature rating of the Alex Tech split loom is -103 to 257 F.

Electrical tape has a rating from 0 to 221 F.

For melting temperature electrical tape clearly wins at 932 F versus 446 F for he split loom.

Traditional split loom has a rating of -40 to 300 F and melts at 482 F.

[Fishspearit]

Originally Posted by boatpoker

Can't you use an MRBF fuse instead ?

Because of the lower internal resistance of the lithium batteries and the size of the banks people are installing they usually require an Amperage Interrupting Current (AIC) of 25,000 amps, requiring the class T fuse.

Do they make MRBF fuses that large? I've only seen them with an AIC of 10,000 amps.

[s/v Jedi]

Originally Posted by Fishspearit

Because of the lower internal resistance of the lithium batteries and the size of the banks people are installing they usually require an Amperage Interrupting Current (AIC) of 25,000 amps, requiring the class T fuse.

Do they make MRBF fuses that large? I've only seen them with an AIC of 10,000 amps.

The class-T fuse AIC is only 20kA so also below what you require.

[wyb2]

Originally Posted by s/v Jedi

Better rethink that… that sleeve is not split, the stuff is h@ll, I have been haunted by it, no more for me

Crud, you’re right, I forgot that not split was even an option. That’s a no go.

Looks like the split stuff is not available with the extra fire ratings, just standard UL/CSA

https://www.mcmaster.com/1459T817

Did find this similar stuff that meets a different flame spec, ASTM E162. It’s about triple the price.

https://www.mcmaster.com/2649K531

[s/v Jedi]

Originally Posted by wyb2

Crud, you’re right, I forgot that not split was even an option. That’s a no go.

Looks like the split stuff is not available with the extra fire ratings, just standard UL/CSA

https://www.mcmaster.com/1459T817

Did find this similar stuff that meets a different flame spec, ASTM E162. It’s about triple the price.

https://www.mcmaster.com/2649K531

But why? The first one is the same. If you want it to be better than required by ABYC (electrical tape and regular split loom will do) why would you buy more expensive plastic? Just put it in metal conduit then and use stainless steel.

I keep it to the split loom I get from Amazon (it’s sold in other places too of course) because when my wiring is melting, I don’t care about how much longer the split loom keeps holding up.

[Fishspearit]

Originally Posted by s/v Jedi

The class-T fuse AIC is only 20kA so also below what you require.

You're right, 20K is the requirement.

11.10.1.2.3 For batteries or battery banks with a CCA rating greater than 2200 CCA or 500 amp hours, battery overcurrent protection shall have a minimum ampere interrupting capacity (AIC) rating as follows:
11.10.1.2.3.1 at least as great as the battery manufacturer’s short circuit rating, or
11.10.1.2.3.2 20 kA at 125 VDC or higher, if a battery manufacturer’s short circuit rating exceeds 10 kA.

[s/v Jedi]

Originally Posted by Fishspearit

You're right, 20K is the requirement.

11.10.1.2.3 For batteries or battery banks with a CCA rating greater than 2200 CCA or 500 amp hours, battery overcurrent protection shall have a minimum ampere interrupting capacity (AIC) rating as follows:
11.10.1.2.3.1 at least as great as the battery manufacturer’s short circuit rating, or
11.10.1.2.3.2 20 kA at 125 VDC or higher, if a battery manufacturer’s short circuit rating exceeds 10 kA.

Yes, so for most LFP installations that use inline BMS with ratings of a couple hundred amps, you should be able to use the MRBF fuse.

It’s clear that the ABYC guidelines are for very large traditional battery banks, not for batteries that limit current and don’t have CCA ratings.

[team karst]

I use a MRBF on each house batt + terminal. This way a battery shorted cell can be mitigated in the worst case.

[wyb2]

Originally Posted by s/v Jedi

But why? The first one is the same. If you want it to be better than required by ABYC (electrical tape and regular split loom will do) why would you buy more expensive plastic? Just put it in metal conduit then and use stainless steel.

I keep it to the split loom I get from Amazon (it’s sold in other places too of course) because when my wiring is melting, I don’t care about how much longer the split loom keeps holding up.

I was just providing the options I was finding that would alleviate any flame/fire concern in response to team karst's statement:

Originally Posted by team karst

🤯 Polyethylene is a poor choice for wire and any wireways. Highly flammable unless its got FR additives. PVC can be easily found with UL fire ratings.

Though I do think that the Amazon stuff is almost certainly polyester, not polyethylene, and the product description is just wrong.

But I agree with you, unless someone points to where flame rated sheath/loom is required or recommended by some standard, I'm completely fine with using the regular stuff.

[Fishspearit]

Originally Posted by s/v Jedi

Yes, so for most LFP installations that use inline BMS with ratings of a couple hundred amps, you should be able to use the MRBF fuse.

It’s clear that the ABYC guidelines are for very large traditional battery banks, not for batteries that limit current and don’t have CCA ratings.

They do address it in one place in the new E-13 standard:

13.7.3A BMS shall have a voltage rating not less than the system voltage and a current rating not less than the total of the ampacities of the main overcurrent protection devices immediately downstream of the battery or battery bank.

But then they also refer to the E-11 standard for overcurrent protection of all types of batteries that I posted above.

It begs the question, and I don't know the answer, do all LFP battery BMS current limiting devices have the appropriate AIC in the case of a short circuit?

I suspect the ABYC isn't quite ready to let the BMS substitute for appropriate AIC ratings for the battery bank overcurrent protection, knowing there are some pretty poor LFP batteries being sold out there.

[s/v Jedi]

Originally Posted by Fishspearit

They do address it in one place in the new E-13 standard:

13.7.3A BMS shall have a voltage rating not less than the system voltage and a current rating not less than the total of the ampacities of the main overcurrent protection devices immediately downstream of the battery or battery bank.

But then they also refer to the E-11 standard for overcurrent protection of all types of batteries that I posted above.

It begs the question, and I don't know the answer, do all LFP battery BMS current limiting devices have the appropriate AIC in the case of a short circuit?

I suspect the ABYC isn't quite ready to let the BMS substitute for appropriate AIC ratings for the battery bank overcurrent protection, knowing there are some pretty poor LFP batteries being sold out there.

Well, yes, the BMS will interrupt a short successfully because they test this. It will be permanently damaged of course.

So the fuse… some leave it out but that’s not right either because the wiring must still be protected like for every circuit.

[thinwater]

Originally Posted by Drennan

Owing to space constraints, I must place a Class-T fuse 25”-30” from my LFP house battery. ABYC code permits up to 40” through “conduit”.

Am I limited to flexible/rigid PVC & metal conduit, or might some other, and more flexible types of cable enclosure be acceptable? If not, I’ll need a much different plan B.

Thank you

Bending PVC pipe or conduit is piss easy, and I'm surprised we don't see this more often. Common practice for electricians.



Search "bending springs" on Amazon and Google how-to. Heat helps (easier and less stress on the pipe), but a few minutes with a heat gun is enough for smaller pipe. I've also used hot water, hot sand, and just placing it in a warm (not hot) oven. hard to beat if going box-to-box. Less mounting effort and support than other methods.