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Discussion Starter · #1 ·
I have 4 condenser. 3 have a max breaker rating of 15a and minimum circuit ampacity of 13 amps, while the other is max breaker of 25 amps and minimum circuit ampacity of 18a. The problem is the engineers have spec 30a breakers for all 4 units. I have talked with them regarding changing the breaker size to match the manufactures ratings, but was told no and to leave them on the 30a breakers. Their reasoning is that with the minimum circuit ampacity of 13a of three of the condensers, a 15 amp breaker violates the 80% loading of the breaker.

I have always understood when sizing breakers and wire for ac condensing units, you always use the name plate info on minimum circuit ampacity for wire size and max breaker for breaker size.

I wanted to see where they got 30a breaker size for the units, so I sized the units based on section 28 and also came up with 30a breakers for each. You would think to stick to what the manufacturer specifies for max Ocp, but it conflicts with the code. You guys ever run into anything like this?
 

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Discussion Starter · #4 ·
I mentioned that if something were to go wrong with the units, that it would probably void the warranty.

I will probably just stick to what the engineers want and keep it as is. But wanted to know for my own knowledge if people ever go against manufacturers specs when it conflicts with code rules.
 

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If an engineer asked me to do what you say (the opposite of the manufacturer's express instructions), I would at least get the engineer to provided a signed/stamped document indicating that, to CMA. Otherwise, when the thing melts and burns something down, your neck is on the chopping block. Max 15 is max 15. there's really no other way to read that. You might even tell the customer that they need to give you a hold harmless document, because their engineer is specifying something that is against the manuf specs, and you cannot be held liable for anything that happens.
 

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I mentioned that if something were to go wrong with the units, that it would probably void the warranty.

I will probably just stick to what the engineers want and keep it as is. But wanted to know for my own knowledge if people ever go against manufacturers specs when it conflicts with code rules.
Just make sure the engineers sign off on it, then they are responsible.;)
 

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Discussion Starter · #7 ·
I did send a email asking them to Rfi what was discussed about leaving the breakers at 30a. They replied to change the breakers to match manufactures specifications.... So in other words a big waste of time.

I sent emails weeks prior saying the breakers need to be changed, or we need fused disconnects at the units to match ratings. I never did get a reply to the email that i sent. Next time I guess I won't wait to see what option they would prefer.

Thanks to all for your input!
 

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In the land of the free we're able to go 400% of FLC if necessary. I don't see the big deal theoretically but manufacturer specs probably trump engineer specs, unless you work in a place exempt of inspections that has engineered supervision. But from what I've read here Canada is kind of crazy on their code enforcement
 

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I have 4 condenser. 3 have a max breaker rating of 15a and minimum circuit ampacity of 13 amps, while the other is max breaker of 25 amps and minimum circuit ampacity of 18a. The problem is the engineers have spec 30a breakers for all 4 units. I have talked with them regarding changing the breaker size to match the manufactures ratings, but was told no and to leave them on the 30a breakers. Their reasoning is that with the minimum circuit ampacity of 13a of three of the condensers, a 15 amp breaker violates the 80% loading of the breaker.

I have always understood when sizing breakers and wire for ac condensing units, you always use the name plate info on minimum circuit ampacity for wire size and max breaker for breaker size.

I wanted to see where they got 30a breaker size for the units, so I sized the units based on section 28 and also came up with 30a breakers for each. You would think to stick to what the manufacturer specifies for max Ocp, but it conflicts with the code. You guys ever run into anything like this?
If all else failed you could keep it on the 30 amp breaker and then fuse it down to 15 amps at the disconnect :thumbup: (assuming the equipment has an acceptable OCPD spec for fuses). Then you're following everyone's rules!

I've had some run-ins with the local refrigeration contractors that can't make heads or tails of their equipment nameplates. They get all huffed and puffed when I run #10s on a 60 amp breaker or something. "You can't do that! You need #6s at least!" Look at the nameplate on the equipment you just hauled up to the roof, dumbass.

Looking forward to Monday. I've got a meeting with the same dudes at a local fast food joint for a new condensor unit. I might print up a couple NEC pages just so I can settle it once and for all.
 

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I have 4 condenser. 3 have a max breaker rating of 15a and minimum circuit ampacity of 13 amps, while the other is max breaker of 25 amps and minimum circuit ampacity of 18a. The problem is the engineers have spec 30a breakers for all 4 units. I have talked with them regarding changing the breaker size to match the manufactures ratings, but was told no and to leave them on the 30a breakers. Their reasoning is that with the minimum circuit ampacity of 13a of three of the condensers, a 15 amp breaker violates the 80% loading of the breaker.

I have always understood when sizing breakers and wire for ac condensing units, you always use the name plate info on minimum circuit ampacity for wire size and max breaker for breaker size.

I wanted to see where they got 30a breaker size for the units, so I sized the units based on section 28 and also came up with 30a breakers for each. You would think to stick to what the manufacturer specifies for max Ocp, but it conflicts with the code. You guys ever run into anything like this?
The mca already has the 25% added.
 

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Discussion Starter · #11 ·
ponyboy said:
In the land of the free we're able to go 400% of FLC if necessary. I don't see the big deal theoretically but manufacturer specs probably trump engineer specs, unless you work in a place exempt of inspections that has engineered supervision. But from what I've read here Canada is kind of crazy on their code enforcement
I think you can go up to 300% here if I remember off the top My head. Obviously dependent on situation, and if you are using fuses or breakers ect.

If the max breaker name plate was missing or scratched off of condensation and I sized this thing to code using the rla of the compressor, i would end up putting the compressor on a 30a breaker.
 

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Discussion Starter · #12 ·
erics37 said:
If all else failed you could keep it on the 30 amp breaker and then fuse it down to 15 amps at the disconnect :thumbup: (assuming the equipment has an acceptable OCPD spec for fuses). Then you're following everyone's rules! I've had some run-ins with the local refrigeration contractors that can't make heads or tails of their equipment nameplates. They get all huffed and puffed when I run #10s on a 60 amp breaker or something. "You can't do that! You need #6s at least!" Look at the nameplate on the equipment you just hauled up to the roof, dumbass. Looking forward to Monday. I've got a meeting with the same dudes at a local fast food joint for a new condensor unit. I might print up a couple NEC pages just so I can settle it once and for all.
I did mention this in email I sent weeks earlier. I was needing to order the disconnects for the units, and I told them if the breakers remain 30a, the disconnects will need to be fused at 25 and 15a at the units or if they wanted the breakers changed, I would order regular disconnects.
 
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