Indoor unit

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kwired said:
One can replace furnace in your little story with VFD and 25 amp breaker with semiconductor fuse and leave the rest of the wording as is and you are telling almost same story just with different equipment involved.

Not sure if you are absolutely serious or joking?

It will lower overall voltage drop on the branch circuit during starting because it limits current, but motor still sees reduced voltage during starting.
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I made a comment to provide voltage drop calculation from power source to fire pump motor due to large distance per nec 2014 to engineer who was mechanical and desiging electrical apparently our AHJ and state allows it as long as registered engineer.

The engineer came back saying boltage drop no lomg necessary since he was providing soft start at the fire pump controller.



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I made a comment to provide voltage drop calculation from power source to fire pump motor due to large distance per nec 2014 to engineer who was mechanical and desiging electrical apparently our AHJ and state allows it as long as registered engineer.

The engineer came back saying voltage drop no lomg necessary since he was providing soft start at the fire pump controller. I was wondering if the engineer is comptent.



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kwired said:
One can replace furnace in your little story with VFD and 25 amp breaker with semiconductor fuse and leave the rest of the wording as is and you are telling almost same story just with different equipment involved.
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That's correct, and either way, your still left holding the bag if you didn't follow the manufacturers recommended OCPD.

JAP>
 
Mgraw said:
No matter what some say the MOCP is not a recommendation. Some manufacturers now list a recommended OCPD size on the equipment tag but it is lower than the MOCP. MOCP is just what it says. MAXIMUM OVER CURRENT PROTECTION.
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Glad your agreeing to what we already learned in post #60.
The manufacturer does recommend the MOCP (MAXIMUM OVERCURRENT PROTECTION) and its 15 Amps.
Why would you want to go any larger than the maximum recommended?

There's simply no need to.

Jap>
 
jap said:
That's correct, and either way, your still left holding the bag if you didn't follow the manufacturers recommended OCPD.

JAP>
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Though it helps if you followed manufacturers recommendations, the fact you installed it still potentially gets you involved in the lawsuit.
 
jap said:
Glad your agreeing to what we already learned in post #60.
The manufacturer does recommend the MOCP (MAXIMUM OVERCURRENT PROTECTION) and its 15 Amps.
Why would you want to go any larger than the maximum recommended?

There's simply no need to.

Jap>
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99%+ of the time I probably will install 15 amp protection myself, as you say there is no need to go more.

Take air handlers that accept electric heating elements - stand alone they only need (and nameplate usually indicates) 15 amp OCPD.

Put a heat strip in it and you often end up with one set of elements and same blower on a 50 or 60 amp breaker.
 
kwired said:
Though it helps if you followed manufacturers recommendations, the fact you installed it still potentially gets you involved in the lawsuit.
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So would you install it per the engineered plans with a 25 amp OCPD to a 20a rated disconnect at the unit or not?

JAP>
 
david luchini said:
I don't see this as a code violation. The Goodman manual calls the MOCP the maximum "RECOMMENDED" fuse or circuit breaker size.
It further states to size wires and fuses properly in accordance with the NEC. It doesn't appear to be a listing requirement to me.
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Agree, I prolly would follow the instructions, but “recommended” does not mean mandated.

Like when the NEC says “shall be permitted” at times, it means you “could” but you do not have to.
 
jumper said:
Agree, I prolly would follow the instructions, but “recommended” does not mean mandated.

Like when the NEC says “shall be permitted” at times, it means you “could” but you do not have to.
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But its best to follow manufacturer. Worse that can happen nuisqnce trip versus other scenario where it does not trip and heat the wire or equipment.

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Max OCPD

Max OCPD

While the manufacturers docs indicate the max OCPD for this unit to be 15 amp, there is footnote 5 which says "recommended". It would be my view that this is an error in the documentation and should be called out to the NRTL and the manufacturer. The instructions can't conflict with the listing. The UL Marking and Application Guide for Heating and Cooling Equipment is very clear on this - the max OCPD is just that and any thing larger would not be in accordance with the listing. This would also include the OCPD type. For those so inclined, here is a link to the quide: https://www.ul.com/wp-content/uploads/2014/04/EHCMG_AG.pdf See section 17.
For the unit in question it would be my view that it would be a violation to install this with an OCPD larger than 15 amp based on the listing.
 
jap said:
So would you install it per the engineered plans with a 25 amp OCPD to a 20a rated disconnect at the unit or not?

JAP>
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Most times not.

Many times they won't even have the furnace installed that was on the specs, though it will be similar capacity.
 
texie said:
While the manufacturers docs indicate the max OCPD for this unit to be 15 amp, there is footnote 5 which says "recommended". It would be my view that this is an error in the documentation and should be called out to the NRTL and the manufacturer. The instructions can't conflict with the listing. The UL Marking and Application Guide for Heating and Cooling Equipment is very clear on this - the max OCPD is just that and any thing larger would not be in accordance with the listing. This would also include the OCPD type. For those so inclined, here is a link to the quide: https://www.ul.com/wp-content/uploads/2014/04/EHCMG_AG.pdf See section 17.
For the unit in question it would be my view that it would be a violation to install this with an OCPD larger than 15 amp based on the listing.
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Then the onus of liability is on them.

One could not reasonably assume that a sparky needs to verify the validity of every set of instructions that comes with equipment.
 
jumper said:
Then the onus of liability is on them.

One could not reasonably assume that a sparky needs to verify the validity of every set of instructions that comes with equipment.
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Ok, fair enough but I'll bet that unit has a data plate on it that indicates the max OCPD. That would say it all to me as an inspector - you can not exceed the max value, period.
 
jumper said:
Then the onus of liability is on them.

One could not reasonably assume that a sparky needs to verify the validity of every set of instructions that comes with equipment.
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The document being quoted is a specification document. This is not an installation manual. The installation manual is very specific in requiring the MOCP on the nameplate be used.
 
texie said:
Ok, fair enough but I'll bet that unit has a data plate on it that indicates the max OCPD. That would say it all to me as an inspector - you can not exceed the max value, period.
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Agreed, if the nameplate said one thing and the instructions another, nameplate rules without a doubt.

This whole thread started because there was no nameplate. Or later OP found it but had not said at beginning. Or was it that some info missing on the nameplate........

IDK, thread has gotten so muddled I have forgotten at this point.
 
This post has become muddled for sure, and, I'd bet that unit has a nameplate on it somewhere with all of the information needed.

JAP>
 
ActionDave said:
Did you happen to notice the question about voltage drop for a fire pump that showed up for a half second?
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Yeah and it was too much for even me to comment on and I got pretty low standards.

Just wait till someone wonders whether AFCI is needed for the circuit and it’s all over.

I am gonna go and see if I can find me a 208V high leg delta service to play with.....
 
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