Soldering job look Ok?
10AWG overkill
It’s a 550W 24V heatbed.
300x300 BigBed.
Ill be running it on a 24v 800w power supply, using a SSR 40A DC to DC
550W 24V means that there will be 22A going through these wires (P=IV so I = P/V)
According to this chart:
https://www.bluesea.com/resources/1437
10AWG cables should be good for up to 30A with less than a 3% voltage drop for cables up to 10ft long.
Bigger cable (lower gauge value) is less resistive thus you have less of a voltage drop across the length of the cable and off course can carry more current.
Solder job looks good. Should use some strain relief and a wire path that allows for gradual flex of most of the wire for durability.
My printer has a fixed bed. I won’t have any issues with flexing or repeated strain :). I’ll clean up the solder flux with some alcohol, which will give it a little bit of a more professional look 
Trying to recall my IPC J-STD training… It looks like you used slightly too much solder on the NTC pads, but that’s just being picky. They look great! You could’ve also had more wire on the 24V pads, but that is more for strength than contact.
Actually yes, I’m using silicone wire. I build my own quadcopters, so I had 10awg left over wire from I’ve if my big builds
Considering that the power in wires are quite big I’d say that it is a really nice job
Looks good to me. Current is in spec as well. Being that your bed doesn’t move just make sure it’s not under tension and otherwise you should be good.
Larger heated beds are a lot easier with mains voltage. Also dc dc ssrs are problematic
@ekaggrat_singh_kalsi agreed. Once you hit a couple hundred watch you should be looking at using an AC pad and a matching SSR.
@ekaggrat_singh_kalsi , @Griffin_Paquette , what is the issue with DC to DC SSRs?
If you write it up properly, you should not have any issues. I even got a 40A SSR which is well oversized to ensure that it can handle the 22A setup.
The only thing I have to ensure is that the load is on the negative side.
Power supply V+ --> SSR Pos
SSR Neg --> Heatbed --> Power supply V-
It’s not necessarily the SSR itself but it higher currents you have to run bigger and higher wattage PSU’s on D.C. whereas if you ran AC, you just pull from the AC terminals on the power supply. I run a 450W 120V heated bed and a into 24V 180W PSU (overkill). Saves space and money. I cared a lot about the space as it was all fitting in my delta.
I’m in Europe. I have a 240V Mains supply
Next upgrade, if this setup fails will be an AC powered Silicone Heatbed.
Thanks for the inputs everyone.
I’ll watch out that the SSR doesn’t do anything weird for the first couple of prints. I’ll also check the temperature of the SSR as well…
On my bed, I turned the connections around so the wires face inwards and had a big loop, then I put high temp RTV over the ends about 1 inch back to strain relief them, my last heater was a thin film one and the stress from the thick wire flexing kept breaking the solder joint with the film. So I let the loop of wire take all the bending stress as the bed moved back and forth.