usao and BenRickert thank you for answering my question. What i forgot to say is that i am not in USA and here where i live current is 240V. I didnt want to bother you anymore so had RL friend electiricnan do the math for me and it seems, for those who might be interested, that regular psu cable of 10A is enough for a single l3+ on a single psu at 240V.

I have few more questions, this tme not regarding power supply.

1) Do i have to update firmware for l3+, or i am good to go with one thats preinstalled? This is what i got:
Hardware Version   1.0.1.2
Kernel Version   Linux 3.8.13 #22 SMP Tue Dec 2 15:26:11 CST 2014
File System Version   Sun Aug 20 16:48:11 CST 2017

2) does anyone know what means "dead" under "Miner status -> pool"?
Out of 3 pools i've set up (hash2coins, aikapool and ispace) first 2 are showing dead and just 3rd one alive. I followed instructions, created worker, put the address and worker info in miner configuration, but still show dead. Is it maybe possible that they dont allow ASIC miners to join? Also, if it helps to better explain what am i asking, in first 2 pools workers arenet shown as active, they have X next to them

3) somewhat related to 2nd question. Can i join any scrypt mining pool with l3+?
Because i've seen that some pools dont have info on how to connect with ASIC miner, just with GPU / CPU miners, for example aikapool

Sorry for bothering general population of this thread, its just that i dont know where else to ask all this