I have a 1000watt PSU and a 750 W PSU I want to start running. Is it safe to plug them both into the same one wall outlet? Is there any danger of overheating or fire and should I use a surge protector? Thanks.
If it is a 110VAC outlet and you are running those PS at or very close to full capasity, NO.
Most electric outlets in the US are rated for 15 amps TOTAL (not per outlet, total for the entire socket), and the circuit they are on is usually has wiring sized for a 15 amp max load.
If those are 90% efficiency at full load, you are pulling over 1900 watts and over 17 amps from the wall with them at full load.
A surge protector does NOTHING for that issue.
*IF* you aren't running them anywhere near full capasity, or if it is a 220vac outlet, it should be OK.
Keep in mind that server and ATX power supply "power rating" is on the OUTPUT of the supply, NOT the input.
Another thing to keep in mind is that a power company does not guarenttee a constant voltage - your wall voltage WILL change over time, depending on the load other folks are putting on the power company and how that load is distributed. It's best to stay within NEC specified limits as those limits take that factor (and many others) into account.
Do NOT assume 120 volts, that's a higher-than-normal voltage on a power circuit - 117vac is the "nominal" but 110 is COMMON and sometimes as low as 100vac in a mild "brownout" condition.
Electric circuits, if you stay within the RATED capasity on amperage, CAN be run safely 100% 24/7 - that's part of what the NEC takes into account - but you do get higher i2r losses when you do so, better to run them a bit under capasity when you can.
That 50 amp breaker is probably the "mains" input breaker for the whole panel, if you're in an apartment or your in an older mobile home park, and will be your TOTAL limit of power the whole panal has comming into it.
The wide 15 amp breaker will be for a 220 circuit probably intended for an electric water heater, electric clothes drier, HIGH capasity A/C outlet, or some such.
The only time I've seen 20 amp circuits in US houses were for circuits leading to a clothes washer or to the kitchen (kitchen appliances can often soak 8-10 amps each and most recent kitchens are assumed to have a few such appliances, like toasters and microwaves and coffee pots etc), or if the house was custom-wired at some point. 15 amp circuits are the norm.
In the US there should never be any 110 lines allowed for safely reason
220 isn't any safer than 110. Both will electrocute you - in fact, 220 is a hair LESS safe but the difference isn't enough to matter on practical terms.