Total Power Budget 83W but total load maybe 100W at power-on

The Netgear GS305EPP has an 83W PoE budget, while your worst-case startup draw (102W) exceeds that. Even if average use is only ~40W, at boot or peak load the switch may shut down ports, stagger power, or fail to power all devices. 

InternJoe wrote:

we plan to use Netgear GS305EPP for a new project. This has 4 PoE ports with a maximum power budget of 83W.

Somehow you mixed up the specs of the unmanaged GS305PP (max 83W) with the GS305EPP (max 120W power budget).

Either way, I'm with stuart012broad​ : If your project requires more than this - even in a small margin - the PoE controller might refuse powering the fourth powered device requesting 25.4 watts.

Look for the GS308EPP instead. It won't kill your hardware budget - and you are on the safe and the supported side with your project. 

InternJoe wrote:

Is our use case OK for GS305EPP?

Probably yes. There is a max 120W power budget according to the GS305EPP data sheet.

PS Sorry, I had a 100W power budget in my head when initially replying here.

InternJoe wrote:

Total Power Budget 83W but total load maybe 100W at power-on

As explained before, the power budget of the GS305EPP is higher than the 83W, it's exactly 120W -> 

Netgear GS305EP, GS305EPP, GS308EP, GS308EPP, GS316EP, GS316EPP Data Sheet 

This not about electrotechnics as you heard about at school.

Each powered device (PD) has does request the power required from the power source (PSE). The PD does request a certain PoE class (by pulsing and/or LLDP signalling) , the PSE does place a reservation accordingly. 

• Type 1 PSE (single-event classification) according to 802.3af: Sends a single voltage pulse and measures the current draw of the PD to determine if it is Class 0, Class 1, Class 2, or Class 3.
• Type 2 PSE (two-event classification) according to 802.3at: Sends a second voltage pulse if the current draw of the PD indicates that it is Class 4 to verify the need for higher power.
• Type 3 and Type 4 PSE (five-event or LLDP classification) according to 802.3bt : Sends out three additional pulses to determine if the device is Class 5, Class 6, Class 7, or Class 8.

Larger PSE might indeed do some stagger, to work around certain power peaks to work around the very worst case.  

It's up to the device resp. the power controller implementation, if this does not power-up some lower priority PD ports, or if it will fail PoE powering a group, or all PD.