Polarity Marking in DC MCBs

Hello everyone,

Recently I happened to see double pole MCBs used in DC circuit for the air-conditioning control panel of Airconditioned railway coaches. While the polarity at the lower end of the MCBs were marked "+" & "-", the polarity at the upper end was maked reverse i.e., "-" & "+" (i.e., marked "-" in the upper side against the + marked lower terminal and "+" on the upper terminal which is having "-" at the lower end). What I mean as upper and lower are the reference position when the MCB is mountedupright.

Initially I thought this could be a mistake. To my astonishment, such marking was available in all the DC MCBs used in all the panels in several AC coaches. I also noticed that the make of these MCBs were of a reputed leading brand of switchgear available in Indian markets.

Can anyone throw me some light on whether the marking is right or wrong? If right, please explain why so?

Thanks in advance

Ramesh.A