24VDC drop on wire

[house]

What is the max 'allowable' voltage allowed to be dropped due to wire resistance on a 24VDC signal wire? I believe the CEC says 6% but didn't know if NEC was the same.

 

[Jim W in Tampa]

That depends on the load. Some relays will not work on lower volts

 

[house]

There is a percentage of the voltage that "may" be dropped based on wiresize. I'm looking for a percentage. The load is irrelevant.

 

[house]

sorry, the load isn't irrelevant, but I can determine the drop based on the load current....I'm just looking for what the NEC says is acceptable, if it says anything at all about it.

 

[Jim W in Tampa]

NEC only suggest a limit on higher voltage and i know of no rule on 24 volts. Check the device specs for min volts. I would think 22 volts would not likely cause trouble. Been told some newer air cond units are very pick about 24 volts ac

 

[dereckbc]

There is no NEC requirement only a footnote of 5%, that is a design requirement. I work a lot with 24 and 48 volt DC plants and our standard is 2%

 

[house]

ok, thanks....