DC voltage drop

[guilio2010]

During a discussion it was brought up that if we had a 24VDC supply and a device that had a operating range of 9-30VDC, and the distance from our power source to the device was long enough to create a 10% Vdrop, it is ok to not increase the wire size as we are still within the 9-30VDC range. I like to maintain 2% as there are other items connected to this and don't want to create any issues, but just wanted to see others feedback. Yes, techically it is correct, but I think it just bad practice and depending on whatever else is connected, you could be affecting things downstream.

Thanks,

 

[dpc]

Depends on the device being powered, but if it will operate down to 9 V, it should not be an issue. You can run dc power remarkably long distances.

 

[ScottyUK]

If the device is a constant power load then be careful with the assumptions your calculation is based on: as the voltage at the point of use drops due to Ohm's Law the current rises to compensate, further increasing the volt-drop due to Ohm's Law. I'm sure you can see where this is going...