Metering Panel

That's the best and only reason, because they can. GA from me, just one more and you reach the coveted 1,000 mark, congratulations!!

Oh, I've already been up to 1,002, but some troll has been eating them.

So, I'll celebrate my second ascension into 1,000 land in just a little over a week.

Those bonuses really come in handy. You get $1.00 USD for each one once you get to 1,000. ;>)

If you have a condo(flat)with about 40 apartments,usually in the groundfloor they have a busbar-chamber from which they feed 40 KWH meters and more meters for common amenities like Lift,water pump,common area lights,gym etc each via a kwh meter.

There is no guarantee that codes are rationally based, even if most of the time they are.

Maybe it's limited to 15 because that's how many meters are accomodated in 1 "standard" panel where you are...

Why does your client need 30 outgoing feeders from 1 panel?

I do not think there is such rule to have only 15 meters per panel. I think they are following this rule for their convenience.Normally they stock particular size of cable for service connection. For this cable ampacity they restrict to no of meters.These norms are followed by TNEB for years. Unfortunately none of the present day TNEB Engineers are in a position to give valid reasons. Present day engineers do not apply their mind.