This review is for the CTSS 125/250V 24Amp soft start module. I had no problems with the order or shipping.Initially I was impressed when the module arrived in a small plastic clam shell case with the large 125/250V wiring diagram on the outside. However, as I looked closer, the wiring diagram wasn't appropriate for use with US 125V hot/neutral (black/white) wiring. I hope the seller will add a 125V specific wiring diagram in near future. I completely ignored the markings on the aluminum shell as I didn't see how that diagram would help at all (didn't match the diagram on clam shell either). So I spent some time searching the web to confirm whether the red or blue wire should be connected to the US 125V “hot” or “neutral” wire and if the black would be considered as the load hot or neutral. This is not something you would want to mix up. Several other sellers of this module identified the red wire as “neutral” and blue as “hot”. But don't be upset if you have reversed these two connections as the module will operate just fine (I've done so with no problem). The black and red wire connect to the load, and assuming the load is isolated, it isn't too important which one connects to which wire on the load (although I'd still make sure the red wire connects to the load neutral if there is/was one). The aluminum cover (heat-sink) of the module is electrically isolated from the electrical wiring as it should be.This module relies on use of a triac operating by phase control to gradually increment the power supplied to the load (motor). I had a 125W heat lamp handy and it was pleasing to see it “glow” to almost (explained later) full brightness. When I watched closely I could almost pick out the increments in brightness as the soft start operated. However, this is hardly new technology as I've found circuit designs from 1970/80's using a triac with 555 timer and transistor zero crossing detection of the AC waveform to do the same thing. Nowadays a very simple micro-controller and triac would replace the older components. The downside to this design is that the triac is always in the circuit. You may have noticed similar several sellers' ads stating that the module should not be used at full rated amperage for more than 30 minutes or something of this sort. That is because the triac, even when fully on, causes a 1-2 volt loss while in operation. A two volt drop (as I measured on my module) would, with a 24 amp load, mean that 48 watts has to be dissipated in the module. Now you should understand why most have this limitation as well as some sort of aluminum shell for a limited heat-sink (and why I said “almost full brightness” earlier – surprisingly just going from 118vac to 120vac with the lamp had a noticeable difference). For longevity I selected this particular soft start module because I could see from the seller's pictures that it was open inside the aluminum/plastic shell. I felt this design would be better for heat dissipation compared to the ones I saw that were potted in an aluminum shell.Another concern with this module is all three wires entering/leaving the module are actually 18 gauge – hardly appropriate for use at 24 amps. I discovered this as one of my installations didn't work with the very short black lead so I cut it off and soldered on a longer wire. Interestingly the “additional” red wiring is a heavier gauge.When I first started looking for a soft start module I was somewhat surprised that I didn't find a module like this one with a bypass relay built in to handle the load after the soft start ramp operation was complete. This would eliminate the 2 volt power loss – a more efficient solution. I somehow thought this would be the “standard design” for a soft start by now. I even found a ST Microelectronics AN4993 created back in 2017 suggesting this hybrid relay soft start and stop approach. Additional research indicated that a more modern solution would be a design using back-to-back power Mosfets (and control circuitry) to replace the triac and relay. I'm still watching and waiting for either of these “newer” solutions to be readily available – manufacturers looking for their next money making product should pay attention.For my 13Amp 10” table saw application, I could use either a separate time delay relay (a 2-3 second delay) that bypasses the soft start module after the timeout or for a less expensive manual approach, I went with using a mom-off-on switch (same amp rating as load) and the soft start module. In this later case the soft start is wired into the momentary side and a direct connection to load is wired using the “on” position (bypassing the soft start module). The switch is physically oriented so “mom” is in the“down” position and “on” in up position. When I start the saw I hold the switch in the down (mom) position for a 1-2-3 count to let the soft start get the motor going and then quickly flip the switch thru off to up (on) position. I've rarely run into motors or electronics that can't handle this brief power interruption as the switch quickly passes thru the “off” position. Note it's important to have the “mom” position oriented down so when you turn off the load, even if you inadvertently pass thru “off” into “mom”; when you release the switch it will automatically move into the “off” position.My next soft start implementation (already have two more of these modules on order) will be with my electronics bench where the 30A+ inrush current for my DIN mount Meanwell power supplies consistently cause brown out conditions to the overhead lighting and other devices when they are already powered on.Overall this soft start module has worked flawlessly since it was installed and I'm so glad I no longer have the horrible startup noise and shuddering of my table saw when I turn it on. This module is definitely worth the price and I wish I'd found it about 20 years ago when I bought the saw. I will again caution about using it near or at the maximum ratings but otherwise I have to say this is a great solution to an annoying problem.

This is perfect for our solar off grid home. We can now safely start our air conditioners without shutting the house down due to the inrush current. I installed these right at the compressor and it was simple to install.