MrCool 18K Mini split wiring help

[PCustoms]

I bet when the data plate says "max fuse" it just means:

"some means of interrupting the power"

So a breaker on the circuit is completely fine. Fuse / breaker no difference. Obviously a fused disconnect adds some manner of protection but is not needed.

(Not an electrician)

You're completely wrong. When it says Max fuse it means use a fuse!

 

[teknikfrog]

You're completely wrong. When it says Max fuse it means use a fuse!

You must be fun at parties. Why don't you post some data points instead?

Here's the label from my Trane 4ton unit:


It has a unfused disconnect, just like every other hvac system I have ever seen in person in my life.

 

[PCustoms]

You must be fun at parties. Why don't you post some data points instead?

I am.

Did you read page 1? I posted plenty of data

Here's the label from my Trane 4ton unit:


It has a unfused disconnect, just like every other hvac system I have ever seen in person in my life.

Notice how that says max fuse/breaker?

 

[teknikfrog]

Does that email from Mr Cool not literally say unfused disconnect in your thread?

 

[PCustoms]

Does that email from Mr Cool not literally say unfused disconnect in your thread?

Yep, and what was the ultimate response based on the equipment label, verified by the electricians?

I'm done arguing with you. Be wrong, I don't care

 

[teknikfrog]

Okay, well moving on this thread without you then.

Generally my understanding is that code defers to a equipment manufacturer for a lot of things. So if a manufacturer says "xyz" I take that to hold a lot more water than what an electrician thinks.

I've done some digging, and it is clearly a widely held belief among sparkies that if the word "fuse" is present then it becomes a requirement, but I am yet to find anything in actual hvacr electrical code that agrees with it. I'd be very interested to find out, from a purely academic perspective.

I actually thought--perhaps erroneously-- that spec for spec, fuses and breakers are essentially treated the same under the electrical code in general. After all, other than response curve, they basically serve the same purpose.

 

[PCustoms]

@wyliesdiesels will gladly explain to you why a fuse is required when the name plate says fuse, I'm sure

 

[teknikfrog]

Went and downloaded the NEC handbook off the **** web. Nothing says integrity and public safety like putting our laws behind paywalls. But anyway, here is what I found:

 

[teknikfrog]

 

[Lovthebass]

I’m sorry I started a thread that became unpleasant. When I spoke to my electrician he said as long as it is connected to the correct sized breaker an unfused disconnect can be used. I chose to use a fused disconnect and a surge protector just in case. It works fine and was only a few more dollars to do it this way. So if you want to feel, better just use a fused disconnect.

 

[hobie18]

If you have access I'd just run new 12/2.

Screwing around with #8, a junction box, wire nuts etc. would frustrate me.

EDIT: don't forget all junction boxes must remain accessible.

Agree. Maybe even 8 or 10 the whole way. Adding a junction in is where added stress comes in. Sure it is minimal. But an extension cord or gold plated/silver contacts...etc.

Great info in this thread. Thanks to all

 

[PCustoms]

I’m sorry I started a thread that became unpleasant. When I spoke to my electrician he said as long as it is connected to the correct sized breaker an unfused disconnect can be used.

The two posts above yours literally cite the NEC code that prove your electrician wrong.

Glad you chose to use a proper disconnect, but it's not about feeling better, it's code

 

[ratflinger]

None of my AC units for the past 30 years have had a fuse, always a disconnect backed up by a breaker.