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diy solar

NH fuses availability in US

MarioP

New Member
Joined
Apr 12, 2024
Messages
15
Location
Rio Rancho, NM
Why are NH fuses not popular in USA?
I'm building a simple, 48v MB31 battery band and will be purchasing Victron MultiPlus II 5000w inverter.
By my calculations 5000W/48v*125%=130amp
So I'm looking for 150-160amp fuse that's rated for 48-60v

In my research, I can go with either a Class T Fuse or NH fuse.

While mega fuses in 58v are available the ICC is only 2,000a, so not quite the 10x safety factor I'm looking for.

Also, it's my understanding that Class-T and NH fuses are the only ones filled with sand to help put out arc during short circuit event.

Most of people here are doing off grid houses with 10k, 18k, 22k and larger systems. What do you use for main battery fuses?
 
We recommend a Class T fuse as close to the battery as possible. The fuses you use after that are up to you.

This is a summary of how the circuit between my battery and inverter is setup.

48v LiFePO4 Battery -> Class T Fuse -> Switch -> Common Bus Bar -> 70v MEGA Fuse 80 amp -> Quattro 48/3000

Here's a link to the 70v 80 amp MEGA fuse I bought:

The MEGA fuses are in my Victron Lynx Distributor.

Mouser.com does sell the NH line of fuses. They've been discussed here on the forum a bit. I'm guessing but they aren't used much in the DIY space due to cost.
 
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I used the Victron Lynx Class-T bus bar with Class T fuses there for my 16kw inverter setup. One 250amp class T per battery.
 
I used the Victron Lynx Class-T bus bar with Class T fuses there for my 16kw inverter setup. One 250amp class T per battery.

I had looked into using that component, but since I have just the single battery it would have been overkill. I also wasn't thrilled with having the Class T Fuse that far from the battery. "Far" being a relative term.
 
I had looked into using that component, but since I have just the single battery it would have been overkill. I also wasn't thrilled with having the Class T Fuse that far from the battery. "Far" being a relative term.
Well the funny thing is my battery vendor was like...why? You have 200amp breaker on each battery and the inverter will shut off if too much draw. I was like well I just like to be thorough :)
 
Well the funny thing is my battery vendor was like...why? You have 200amp breaker on each battery and the inverter will shut off if too much draw. I was like well I just like to be thorough :)
There's very few built-in battery breakers that I would trust to interrupt a short when you start having multiple batteries in parallel so I'd agree with you.

The MEGA fuses again have very low AIC which is fine when you have few batteries in parallel the issue is when you start having a larger system with a lot of batteries in parallel. It just doesn't seem safe if you had 20 100Ah 48V server rack batteries in parallel for example to rely on one of those dinky breakers if one battery shorted. I'd like to be proven otherwise.
 
There's very few built-in battery breakers that I would trust to interrupt a short when you start having multiple batteries in parallel so I'd agree with you.

The MEGA fuses again have very low AIC which is fine when you have few batteries in parallel the issue is when you start having a larger system with a lot of batteries in parallel. It just doesn't seem safe if you had 20 100Ah 48V server rack batteries in parallel for example to rely on one of those dinky breakers if one battery shorted. I'd like to be proven otherwise.
Yeah I agree, mine is 4 x 300Ah so not super big but a fair amount of power.
 
The NH fuses were developed as substation fuses in britian in the 40s.... There are 6 sizes of them commonly available. And there are multiple blow curves. The gG class are slow blow battery fuses and the aR class are fast blow that are basically equivalent of the class T JLLN fuses we generally recommend. The aM class is very fast short circuit and slow overload.

One reason they aren't used more in DIY in the states is the cost of them usually exceeds the cost of the class T and holder. The other reason is the naked holders need to have something over them, and the enclosed box style holders are several hundred dollars. You also need a puller handle to change them... the mounting block springs are super stiff.
 
There's very few built-in battery breakers that I would trust to interrupt a short when you start having multiple batteries in parallel so I'd agree with you.

The MEGA fuses again have very low AIC which is fine when you have few batteries in parallel the issue is when you start having a larger system with a lot of batteries in parallel. It just doesn't seem safe if you had 20 100Ah 48V server rack batteries in parallel for example to rely on one of those dinky breakers if one battery shorted. I'd like to be proven otherwise.

I completely agree with you. It would be dumb to use a Lynx Distributor (with MEGA fuses) to parallel connect multiple batteries.
 
My rules -

12v - 4 or less - MRBF on the post - all connected to bus bar - class T between the bus bar and the inverter.
24v - MRBF on the battery post (optional) - class T in the line or attached to the bus bar - class T in the line to the inverter
48v - class T per battery to the bus bar, class T to the inverter

In the line between the class T and inverter I also recommend a MCCB
This sort of thing to be used as an on/off switch. If you are running a setup with 2 sets of bus bars and a class T in the line between the battery bar and the inverter/SCC/etc bus bar then the MCCB would also go in that line.

NOTE - example - I bought the DiHool breaker listed above off aliexpress for $35 verse $101 - waiting on it to arrive and compare to see if it is real or fake.
 
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The NH fuses were developed as substation fuses in britian in the 40s
No, you got the wrong side ;)... NH fuses came from Germany in the 1940's.

DIN (Deutsches Institut für Normung) standard 43620

We had BS88 fuses over here.
 
No, you got the wrong side ;)... NH fuses came from Germany in the 1940's.

DIN (Deutsches Institut für Normung) standard 43620

We had BS88 fuses over here.


AH HA... well then I am mixing my creation myths for the BS88 and the NH series.
 
In the line between the class T and inverter I also recommend a MCCB
This sort of thing to be used as an on/off switch. If you are running a setup with 2 sets of bus bars and a class T in the line between the battery bar and the inverter/SCC/etc bus bar then the MCCB would also go in that line.
https://www.amazon.com/DIHOOL-Circu...itch/dp/B0CJBB6J5D?ref_=ast_sto_dp&th=1&psc=1
Still not sure I would trust those when you can't find spec sheet on it. Plus it is claiming 20kA AIC at 1000V DC??
 
My rules -

12v - 4 or less - MRBF on the post - all connected to bus bar - class T between the bus bar and the inverter.
24v - MRBF on the battery post (optional) - class T in the line or attached to the bus bar - class T in the line to the inverter
48v - class T per battery to the bus bar, class T to the inverter

In the line between the class T and inverter I also recommend a MCCB
This sort of thing to be used as an on/off switch. If you are running a setup with 2 sets of bus bars and a class T in the line between the battery bar and the inverter/SCC/etc bus bar then the MCCB would also go in that line.

NOTE - example - I bought the DiHool breaker listed above off aliexpress for $35 verse $101 - waiting on it to arrive and compare to see if it is real or fake.
Thanks. Question: why 2 poles for DC? What's the point of isolating the negative/ground?
 
Thanks. Question: why 2 poles for DC? What's the point of isolating the negative/ground?

Well, in the PV lines you want to disconnect both lines... for a battery just a single pole is fine... also with these you can loop them back on themselves to double the voltage.... I think that also doubles the AIC but don't quote me until I look it up... it would double the gap the arc would have to travel.

And unless you are in a mobile setup the negative of the the battery floats, it should not be tied to a grounding system.... unfortunate the common way we use ground.... the equipment shells and battery rack and anything else not carrying current is tied to the grounding system... but DC negative is not ground. So breaking both positive and negative at once is actually a good thing.

There are some differences when on a mobile setup or on a boat in how you hook things up.
 
Why are NH fuses not popular in USA?
I'm building a simple, 48v MB31 battery band and will be purchasing Victron MultiPlus II 5000w inverter.
By my calculations 5000W/48v*125%=130amp
So I'm looking for 150-160amp fuse that's rated for 48-60v

In my research, I can go with either a Class T Fuse or NH fuse.

While mega fuses in 58v are available the ICC is only 2,000a, so not quite the 10x safety factor I'm looking for.

Also, it's my understanding that Class-T and NH fuses are the only ones filled with sand to help put out arc during short circuit event.

Most of people here are doing off grid houses with 10k, 18k, 22k and larger systems. What do you use for main battery fuses?


Reason is more easy.
In the eu those fuse are cheap.
In the usa its not use so its import so it cost more.
Funny thing is that t-fuses in the EU cost more than in the usa.

That is the big reason

125a model 500 volts dc. 10 euro.
 

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I'm also curious why NH fuses aren't often used.
I'm planning to use this fuse holder for my 48v system.
I just purchased these fuses to go in it. Is anyone else using these?
 

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I'm also curious why NH fuses aren't often used.
I'm planning to use this fuse holder for my 48v system.
I just purchased these fuses to go in it. Is anyone else using these?
Do you have a link or source for these? I'm looking at both AliEx and Alibaba. Found few for reasonable price, but shipping kills the deal.
The only holders I found in US are naked, so I would have to put them in a single gang plastic box, or 3d print something. Not really looking to complicate things.
 
In my application, I will have a single 48v 314ah battery bank under the couch inside the RV, with an option to put 2nd and possibly 3rd if storage needs require it.
I'm considering installing a fuse right on the battery box, just need to make sure I have clearances from the metal case.
Then, a shut off switch on the side of the couch (so I don't have to get people off, fiddle with raising the cushion, etc).
From there, straight shot below, where current led acid batteries live, where I will be installing a Victron 5kv inverter. I will probably install circut breaker just before the inverter as another point of disconnect, accessible from outside of RV.
I do not currently have solar panels, and probably won't for a while. I figured that we would normally park in the RV park or in the wooded areas where solar wouldn't be effective.
For topping off batteries, I'll run the built in Onan 5500 generator, outputting 46amp at 120vac. 1731666343505.pngIMG_6342.jpg
 
Is anyone else using these?
Yes. I use NH fuses and a Jean-Muller disconnector.

The good thing is that NH-00 disconnectors support both NH-000 and NH-00 size fueses. The body of the fuses themselves are different widths (28mm vs. 21mm), but the 00 and 000 have same length and height of blade (79mm x 53mm). So all the "00" disconnectors that I have seen will also take a "000" fuse. I upgraded the fuses in my Jean-Muller Keto Disconnector from 80A "000" to 125A "00" when I switched from my RH1 to EH1P Solis.
 
Do you have a link or source for these? I'm looking at both AliEx and Alibaba. Found few for reasonable price, but shipping kills the deal.
The only holders I found in US are naked, so I would have to put them in a single gang plastic box, or 3d print something. Not really looking to complicate things.
Yes, no problems I'll get a link for you tomorrow, I'm in Australia and it's getting late here now 👍🏼
 
Here is the link to the fuses
I just found this on AliExpress:
AU$15.92 | CHINT Fuse Core RT36-00 NT00 6A 20A 25A 32A 40A 50A 63A 80A 100A 125A 160A 200A 250A 300A NT1 NT2 NT3 Ceramic Resistor Fuse
I purchased my fuse holder a few years ago on ebay I think but these are available on aliexpress also
 

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