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Thread: Indoor unit

  1. #131
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    Quote Originally Posted by Mgraw View Post
    You could run a 25 amp circuit to a disconnect and then fuse the disconnect at 15 amps. If this is a commercial job, at least the engineers I deal with, always spec a fused disconnect at the unit.
    Sounds like what one may expect in many cases. 25 amp supply covers worst case scenario, select fuse for actual equipment.

    Quote Originally Posted by jap View Post

    If this is a bid job and the engineer actually indicated the disconnect to be a "Non Fused" 20a disconnect, then a change order should be submitted to change the "Non Fused" disconnect to a 30 amp "Fused Disconnect" with 15 amp fuses and be done with it.

    JAP>
    I think many will just put in 15 amp breaker and be done with it, they do have to pass electrical inspection.

  2. #132
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    Quote Originally Posted by kwired View Post
    ...25 amp supply covers worst case scenario, select fuse for actual equipment.....
    Lazy engineering by someone not paying for the materials.

  3. #133
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    Quote Originally Posted by MAC702 View Post
    Lazy engineering by someone not paying for the materials.
    I do agree with that. Guy probably never got any unit details just went with worst case possible and designed for that. May even put in that section of plans before specific unit was selected.

  4. #134
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    Quote Originally Posted by kwired View Post
    I do agree with that. Guy probably never got any unit details just went with worst case possible and designed for that. May even put in that section of plans before specific unit was selected.
    Ok well maybe lazy but whats up with the engineers attitude no one really asked him that for 30 years. So he is putting 25 amps disconnect where manufacturer is recommending 15 amps and no AHJ caught it?

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  5. #135
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    Ok well maybe lazy but whats up with the engineers attitude no one really asked him that for 30 years. So he is putting 25 amps circuit breaker where manufacturer is recommending 15 amps and no AHJ caught it? That guy must really have good contractor who back in their mind says oh the engineer is being stupid agsin let me correct his mistakes.



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  6. #136
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    Quote Originally Posted by codequestion View Post
    Ok well maybe lazy but whats up with the engineers attitude no one really asked him that for 30 years. So he is putting 25 amps disconnect where manufacturer is recommending 15 amps and no AHJ caught it?

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    I didn't see anywhere if it was asked, but is this a commercial or residential setup?

  7. #137
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    Quote Originally Posted by gadfly56 View Post
    I didn't see anywhere if it was asked, but is this a commercial or residential setup?
    Commericial in public storage.

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  8. #138
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    Quote Originally Posted by jap View Post
    Per post #73 the OP stated the engineer has drawn a 25 amp circuit to a 20a NF Disconnect.
    I don't see how this could be since actual NF disconnects start a 30 amps.

    Generally an engineer will draw a disconnect symbol on the prints and if it has a (20) beside it that means it should be a 30 amp fused disconnect fused at 20amps.

    If this is actually the case, then the OP misread the print, since even it were indicated to be fused at 20 amps the change to a 15 amp fuse would not result in a price increase and no change order would be needed.

    If this is a bid job and the engineer actually indicated the disconnect to be a "Non Fused" 20a disconnect, then a change order should be submitted to change the "Non Fused" disconnect to a 30 amp "Fused Disconnect" with 15 amp fuses and be done with it.

    JAP>
    Typically here an engineer will spec a breaker size based on the unit the mechanical engineer spec'd. It is rare that the spec'd unit is actually installed. If say a carrier abc unit is spec'd but a trane dealer gets the job then the engineer may accept trane xyz for the job. Usually the bid specs will say carrier abc or comparable unit.

    I have not come across an engineer specifying what fuse size for a disconnect. They will spec breaker size but the fuse size is generally left to the electrical contractor

  9. #139
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    Quote Originally Posted by Mgraw View Post
    Typically here an engineer will spec a breaker size based on the unit the mechanical engineer spec'd. It is rare that the spec'd unit is actually installed. If say a carrier abc unit is spec'd but a trane dealer gets the job then the engineer may accept trane xyz for the job. Usually the bid specs will say carrier abc or comparable unit.

    I have not come across an engineer specifying what fuse size for a disconnect. They will spec breaker size but the fuse size is generally left to the electrical contractor
    Its not use he is sizing the breaker in panel.

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  10. #140
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    Quote Originally Posted by codequestion View Post
    Ok well maybe lazy but whats up with the engineers attitude no one really asked him that for 30 years. So he is putting 25 amps disconnect where manufacturer is recommending 15 amps and no AHJ caught it?

    Sent from my SM-G935U using Tapatalk
    Well 30 years ago that unit maybe was closer to truly needing 25 amp circuit then today

    Did they really improve them that much? IDK, they may be more energy efficient, but I think they break down more then they used to which blows even bigger hole in the owner's checkbook then the inefficiency did.

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