HVAC conductor and breaker sizing - AGAIN???

[ActionDave]

I coulda sworn I read somewhere in my training material that you had to maintain the same gage conductors in the same branch circuit from the loadcenter to the final load of that branch circuit? ....

Nope. You may have read it but it's not correct information.

 

[augie47]

If I read that correctly With 23.9 min circuit ampacity ..................................................................................................
The more I think of this 23.9 next higher breaker is 25. You could probably run 20 amp wire fuse up to 25. However we would install 30 amp to condensor. and 20 to attic and be done.
Hope this helps.

There are so many post I don't want to have to review each one but this keeps haunting me.
Perhaps I'm reading out of context but: If the MCA is 23.9, you can not use a 20 amp wire.
When all settles you need a condujctior with an amapcity of 23.9 amps and an overcurrent device that does not exceed the M(ax)OCP listed on the nameplate.

 

[kwired]

I coulda sworn I read somewhere in my training material that you had to maintain the same gage conductors in the same branch circuit from the loadcenter to the final load of that branch circuit? Some times I feel like my head is going to explode; drinking from the firehose of knowledge.

Larger conductors are run all the time for voltage drop reasons. Single family dwellings and small commercial buildings maybe don't see much of it because circuit lengths typically are not long enough to make it necessary.

An oversized conductor does not create hazards like an undersized one does. Main issue with oversized is usually terminations are not going to accommodate much for oversizing.

 

[dkidd]

Main issue with oversized is usually terminations are not going to accommodate much for oversizing.

Or letting in too much electricity. :happysad:

 

[iwire]

Or letting in too much electricity. :happysad:

In a way that is true, larger conductors result in higher available fault current which might in rare instances raise the needed AIC rating of equipment.

 

[kwired]

In a way that is true, larger conductors result in higher available fault current which might in rare instances raise the needed AIC rating of equipment.

I agree. Also allows higher starting surge for motors or other inductive loads, which can be good or bad depending on circumstances.

 

[spurlockda]

Thanks everyone

Thanks everyone

I'm starting to see a lot of folks who don't want this thread to go on seemingly forever so while I have learned something from most every post and truly appreciate everyone's patience.

I guess this thread can be closed for further comments.

Again, thanks everyone.

V/r,
Dave