100% Jonathan! Stop wondering whether you are correct or not. You understand the subject correctly and the analogy to a pressure relief valve in a fluid system is absolutely pertinent. Without going into electron flow theory, i agree that it does not matter where on the bus it is located. I'm an old retired electrical engineer with 50 years experience.

Interesting note, I installed the ULTRA in 2011. The 2010 version of the manual stated to use a 15 amp breaker which I did. I just noticed that the 2015 version of the manual states to use a 50 amp breaker in order to achieve the full potential of the CHSPT2ULTRA version, lol. Only the CHSPT2SURGE uses a 15 amp breaker. Thanks Eaton! I paid for a better product, but have had it installed on a 15 amp breaker for 12 years.

I just installed the same Eaton unit, watched many videos in regards to placement, wiring etc... I purchased a 15 amp bi-pole breaker, installed at the left leg at the top of the panel, first two slots, dedicated to the Eaton, nothing else on the circuit. I mounted the Eaton directly across from the breaker to have a short run. Hooked up the neutral and ground, and good to go. I also purchased and installed a KVAR unit, not for energy savings, but for its real purpose, softening the load on the panel when a motor starts up, like your well or refrigerator. I had issues with LED lights flickering when the well or refrigerator started up, those issues are now GONE! I installed that on a dedicated 20 amp bi-pole breaker at the top right side of the panel. The darn thing works. So, if you are having issues with lights flickering when an electric motor in your house starts up, you may want to look at a KVAR unit for the whole house. If you are having issues at the AC compressor, they make smaller soft start units that can easily be installed inside the unit, simply wire in at the units control panel, they run around $20. Hope this helps!

Great Video. Again they are clueless, you'd still get current to all the other circuits if it was even in the first slot, so putting it in the first or the last doesnt make a difference, the 2ft of travel to the surge protector is still shorter than the 50ft it needs to travel to the nearest appliance.

My guess is that the impedance of the bus bar is so low it’s not a contributing factor. The same goes for the fixed impedance of the breaker which has to be in place. However, the length of the red/black leads from the breaker to the SPD which need to be TWISTED TOGETHER to minimize their impedance has the greatest impact on the clamping voltage in the Eaton videos which appears to be linear. So, what’s the best location? Whichever knockout minimizes the length of the wires to the breaker which is exactly how their load centres with the integrated SPD mount are designed. I went looking for info from Eaton to verify my theory and this video confirms it: kzfaq.info/get/bejne/g9ake6mj1rXWiYk.html&si=EnSIkaIECMiOmarE&t=424

Just curious. Did the installation instructions comment about where the optimum placement should be?

Hi, The question here is one of what you can do for optimizing the protection you get out of the device. Keeping a short lead length maximizes the performance of the surge protector in reducing the size of the spike you can observe on the bus. Eaton has a few brief instructional video on their website. Unfortunately they do not seem to post copies of their videos on KZfaq so they are hard to find -- But for example they have a great, brief 61 second video showing the effect of the lead length to the surge protection device on how good the voltage clamping for a spike is. In the video for a 7,000 volt test spike, with the device mounted directly on the bus at the entrance, the peak current is 382 v; when the same device is mounted on the side by main shutoff (looks like ~12" lead), the spike on the bus was 495 v, and that same device mounted with 3 feet of lead lets the bus voltage spike up go up to 882 v. So if at all possible, mounting at the very top of the bus with leads as short as possible maximizes your protection. See www.eaton.com/us/en-us/products/backup-power-ups-surge-it-power-distribution/surge-protection/surge-protection-faq.html As you noted the Eaton Ultra the installation manual does suggest two steps to maximize performance: "• When connecting the wires from the CHSP to the electrical system, cut the wires as necessary to keep them as short as possible - 12 inches (30 cm) or less is recommended. • To maximize the CHSP’s performance, twist and bind the wires together to reduce the impedance of the wire (one twist / inch)." In Eaton's own panel you showed the Ultra is about 3.75" so it looks like total additional lead length is 5" more by having it down at the bottom of that short panel. In the photo of the panel they also didn't twist the leads much. All of which doesn't mean it won't work but the trade off is a bit of boost in performance for the one time cost of labor. Finally, one deficit about the Eaton Ultra is there is an audio alarm. Most, like the Eaton Ultra have just have indicator lights so you'll have to notice when the device gets knocked out. The Siemens FS140 has an audible alarm but alas for us they were out of stock everywhere when our installation was being done so we went with the Eaton.