Undersized supply cable.

[tek9]

We got called over a 12gauge 5 core cable to an A/C unit FLA 16A per phase LRA 80A,40A breaker,inspector said we'd have to upsize the cable,consumer mains,i disagreed,until recently,OCPD was allowed to exist at the panel or the unit,the breaker only giving s/c protection,unit said,Carrier Airconditioning Corporation,Newark New Jersey,use 40A breaker,guy got us to change it to 20a,kept nuisance tripping,so my daughter changed it back,Unit had been working fine for 25 years till Mrs Possum came along,causing corrosion on the condenser,a local HVAC guy repaired the unit,removed the animals,put a nest box in a tree for them,then the inspector comes along.What do you guys think?

 

[petersonra]

I am not entirely sure what your point is.

 

[busman]

What's the MCA on the unit nameplate?

Mark

 

[augie47]

If the nameplate calls shows a MCA no greater than the ampacity of the cable, and a 40 amp MaxOCP, then I would say all is fine since, as you state, the breaker is providing short-circuit protection as designed..
(Under today's NEC your cable might not meet Code if it runs in an outside location)

 

[kwired]

If the nameplate calls shows a MCA no greater than the ampacity of the cable, and a 40 amp MaxOCP, then I would say all is fine since, as you state, the breaker is providing short-circuit protection as designed..
(Under today's NEC your cable might not meet Code if it runs in an outside location)

OP may not be under NEC either. But I can easily see with a FLA of 16 that it likely will need at least a 30 amp breaker or it will likely not hold during starting no matter what code applies.