Having an issue with inspector

[Tulsa Electrician]

But my real point wasn't that it isn't an issue, but rather that it shouldn't be.

I can agree with that.
Sometimes I don't understand correctly. Thanks

 

[ggunn]

If the manufacturer wants to instruct you to use fuses only, it should say "Fuse Only" on the nameplate.

But as we are all aware, sometimes painfully so, what is and what should be are frequently at odds.

 

[jaggedben]

My opinion is only semi-informed here, but it seems to me that the issue is UL being stuck in the mud and perhaps grubbing futilely for more money for testing.

If fuses are considered more effective than HACR breakers (or is it vice versa? But whichever.) then manufacturers should be allowed to do their test with the breaker and put 'Max fuse or HACR breaker' on the label. Done, and we can all stop wasting time and money. Installers don't get dinged by inspectors for something the manufacturer was never going to pay for. Who cares if a higher rated fuse would still be safe, we don't need that.

I just can't really believe it makes a real world difference.

 

[wwhitney]

Has anyone ever seen equipment that listed both fuse and HACR ratings and they were *different*?

This just happened to come up on another forum.

Cheers, Wayne

 

[xformer]

I would think that, generally speaking, fuses open more quickly for motor protection.

Although fuses open faster than CB's its still the job of the OL's to protect the motor.

 

[jim dungar]

Although fuses open faster than CB's its still the job of the OL's to protect the motor.

Yep.
The branch circuit device is usually for Short Circuit and Ground protection, both of which typically happen after a failure has already occurred.

 

[kwired]

This just happened to come up on another forum.

Cheers, Wayne

View attachment 2568178

Sort of doesn't make too much sense on this plate. Compressor has RLA of 19 and apparently two fans with FLA of .6 amps. Normally that should give you a MCA of about 25 amps but plate says MCA of 42. Don't know why the difference for fuse vs breaker but either is in about the range I would expect for a compressor with RLA of 19. If variable speed compressor, reality says you can get by easily with 35 and maybe even 30 amp OCPD's.

 

[wwhitney]

Sort of doesn't make too much sense on this plate. Compressor has RLA of 19 and apparently two fans with FLA of .6 amps. Normally that should give you a MCA of about 25 amps but plate says MCA of 42.

Yeah, I wasn't sure about where the additional 17A of load would be coming from. Maybe a large electric resistance defrost heater?

Cheers, Wayne

 

[kwired]

Yeah, I wasn't sure about where the additional 17A of load would be coming from. Maybe a large electric resistance defrost heater?

Cheers, Wayne

If so then that load should be listed on the nameplate though.

 

[jaggedben]

If so then that load should be listed on the nameplate though.

Doubtful if would be in the indoor unit and could be any of a number of power ratings.

 

[jaggedben]

This just happened to come up on another forum.

Cheers, Wayne

View attachment 2568178

And from experience, installer will put it on a 50A breaker.

 

[kwired]

Doubtful if would be in the indoor unit and could be any of a number of power ratings.

I think we are talking about the label in post 84, the nameplate for an outdoor unit. Probably a mini-split that powers an indoor air handler that has minimal load of a blower and some controls. If there were significant heating elements in the indoor unit it probably more of a conventional split unit and the indoor section is supplied by it's own circuit.

 

[Treg the electrician]

exactly my thoughts! i did the correction it only cost our company $200 in parts and a trip out there im moving on

 

[wwhitney]

Yeah, I wasn't sure about where the additional 17A of load would be coming from.

That outdoor unit apparently supports up to 8 indoor units. So if the power to the indoor units comes from the outdoor unit, maybe it is just a 2.1A allowance for each possible indoor unit.

Cheers, Wayne

 

[kwired]

That outdoor unit apparently supports up to 8 indoor units. So if the power to the indoor units comes from the outdoor unit, maybe it is just a 2.1A allowance for each possible indoor unit.

Cheers, Wayne

I wondered what the "W(output)" with a value of 74+74 is all about. But still makes no sense other than maybe that is output watts of apparently two outdoor blowers?

From what I seen from mini-splits 2.1 amps at 208-240 volts would be a pretty significant indoor blower. All other indoor unit load is almost negligible.

 

[GoldDigger]

I wondered what the "W(output)" with a value of 74+74 is all about. But still makes no sense other than maybe that is output watts of apparently two outdoor blowers?

From what I seen from mini-splits 2.1 amps at 208-240 volts would be a pretty significant indoor blower. All other indoor unit load is almost negligible.

Am I correct to assume that, unlike ducted heat pump systems, mini-splits do not incorporate a resistance heating option? I know that my MIL's Panasonic system just runs out of heating capacity both at low outdoor temps and when low on refrigerant.

 

[gadfly56]

Am I correct to assume that, unlike ducted heat pump systems, mini-splits do not incorporate a resistance heating option? I know that my MIL's Panasonic system just runs out of heating capacity both at low outdoor temps and when low on refrigerant.

To the best of my knowledge, that is the case. Undoubtedly, someone out there offers this as an option, but it isn't usual, in my experience.

 

[hornetd]

110.3 Examination, Identification, Installation, Use, and Listing
(Product Certification) of Equipment.
(B) Installation and Use. Listed or labeled equipment shall be
installed and used in accordance with any instructions included
in the listing or labeling.

It appears to me that for a manufacturers instructions to be comparable to the label they would have to be included in either the listing, of the item not the listing standard, or on the label which it clearly is not. So unless the option of using a circuit breaker were included in the actual listing in the white book it cannot overrule the labeling which pretty clearly calls for fusing.

Tom Horne

 

[mtnelect]

When I am designing a HVAC system I always look first at the "Technical" information to match it to the "Heat Load". Then after selecting the unit I look to the "Installation" manual. As far as I can remember, I always had a choice between a breaker or a fuse per the manufacturer's specifications. .

 

[ekbrunn]

I agree with the inspector's position in failing the installation. Some years back I had a large AHU installation (chilled water, not DX) where the nameplate required a 15 OCPD for the internal lighting and service receptacle. When I cited the electrician he showed me where the engineer had required a 20 amp OCPD. He opened one of the boxes and we saw #14 AWG conductors were installed! I gave him the choice of providing a 15 amp OCPD (separate fuses or new branch circuit breaker) or rewiring the lighting and receptacles.
It seems the manufacturer, as a cost savings measure, started installing #14 AWG conductors in the AHU for the lighting instead of #12 AWG. I looked at a couple of other units the were previously installed. They were marked for 20 amp OCPD.
When I contacted the engineer to notify him of the change so he could modify his notes, he stated he only goes by what the manufacturer paperwork says. It is up to the installer to provide a compliant installation! Like someone else said; nameplate beats instructions.
BTW, the electrician changed out the circuit breaker.