Panelboard voltage drop

[hhsting]

I have new panelboard outside of bulisong fed from inside building existing switchboard feeder breaker 300 feet away . The panelboard is 208/120V, 100 amps main circuit breaker, spare and loaded circuit breakers, demand load of 60 amps. The panelboard is capable of loading up to 100 amps in future since spares provided but for now is loaded to 60 amps. Now the question is voltage drop calculation should it take into account 60 amps or 100 amps?

 

[roger]

What would be the best design in your opinion?

Roger

 

[kwired]

Do you want to pull supply conductors just one time or do you want to change them when adding load if voltage drop is an issue then?

Somewhat comes down to what kind of voltage drop can be tolerated whether by equipment performance, owner preference, energy code, etc.

 

[sameguy]

With anything I try for the full load of the circuit unless I'm bidding, then I bid what is written.
If it was me I would go for the full load potential of the panel unless your bidding.

 

[kwired]

With anything I try for the full load of the circuit unless I'm bidding, then I bid what is written.
If it was me I would go for the full load potential of the panel unless your bidding.

Yes, if you are bidding you plan to put in what was specified, if you are bidding a design/build, you need to inform owner what you may have done to allow for future expansion, otherwise you might have done them a favor for down the road but came in too high and they didn't know about the favor. If you are design/building but not bidding against others, you work with owner to do what they want part of what builds a stronger relation with owner is informing them what it cost to do it this way now, vs what it will cost long term to change down the road. Especially if that change down the road is something fairly known to be a good possibility.

 

[roger]

With anything I try for the full load of the circuit unless I'm bidding, then I bid what is written.
If it was me I would go for the full load potential of the panel unless your bidding.

The OP works for the designer.

Roger

 

[kwired]

The OP works for the designer.

Roger

Then he needs to either know the owners needs, or talk with them about whether they want to spend a little extra now or possibly spend even more later when it needs upgraded. But for no more difference than this will likely add to overall initial cost in this case most probably just design for the future and never ask the owner such questions.

Would be a lot different if trying to decide if one should install a 100 amp supply now vs a 400 amp supply circuit for possible future needs, here OP might only be looking at an increase of one conductor size being the main issue.

 

[hhsting]

Then he needs to either know the owners needs, or talk with them about whether they want to spend a little extra now or possibly spend even more later when it needs upgraded. But for no more difference than this will likely add to overall initial cost in this case most probably just design for the future and never ask the owner such questions.

Would be a lot different if trying to decide if one should install a 100 amp supply now vs a 400 amp supply circuit for possible future needs, here OP might only be looking at an increase of one conductor size being the main issue.

AHJ cannot say anything in this issue?

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[kwired]

AHJ cannot say anything in this issue?

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From NEC perspective, as long as conductor ampacity is not exceeded and overcurrent protection is proper -no. If there is an energy code being enforced that covers this type of thing, maybe.

Add: if serving certain items in chapters 5-7 maybe voltage drop is covered by NEC, but as a general rule NEC doesn't have voltage drop requirements, just suggestions in informational note.

 

[roger]

Then he needs to either know the owners needs, or talk with them about whether they want to spend a little extra now or possibly spend even more later when it needs upgraded.
But for no more difference than this will likely add to overall initial cost in this case most probably just design for the future and never ask the owner such questions.

Yep.

Would be a lot different if trying to decide if one should install a 100 amp supply now vs a 400 amp supply circuit for possible future needs, here OP might only be looking at an increase of one conductor size being the main issue.

Yep again.

Roger