Features: 240v NEMA 14-50 UL listed Up to 50A True heavy duty Worked flawlessly Worked with splitter Has cover and ability to lock Worked with extension cords Maximum Watts, 12,000W Energy dissipation is 4,200 Joules Voltage range on each side is 90V-140V Underwriters Laboratories (UL) Drawbacks: This baby is big and heavy, but it can do its job Specification sheet is a little vague NEMA 14-50 plug/receptacle Clamping voltage, is a mystery How this arrived This arrived in a somewhat sturdy cardboard retail package that measured 21” x 3.75” x 3.25%. The Surge Protection Device (SPD) was inside, strapped to a cardboard insert. It’s massive, measuring about 17.5 inches long and weighing about 2LB x 5OZ. The cable is about 0.87” which is just over 22mm. Both the plug and receptacle are molded. The NEMA 14-50R side is about 3.5” x 2.50” and the 14-50P side is 3.5” x 2.50” x 2.75”. There is a pull down two (2) finger T handle on each molded end to assist in pulling apart. The Surgeguard read-out box is 4” x 2” x 3”. The brand SOUTHWIRE is a name brand I am familiar with, and they did right by obtaining UL evaluation, it’s marked on the surge protection device too. [The UL mark, which this charger has, demonstrates, to me, that this product had been rigorously tested to class applicable standards. My understanding is that the UL standard may also meet the standards for Electrical Testing Laboratories (ETL) and possibly the CSA Group (CSA) standards. These references though are not marked on the surge device. I looked up this devices file with UL. [Consider doing your own research.] What the UL mark tells me That UL mark tells me the manufacturer is trying to tell the world they seek high standards and stand behind what they sell. So, if something is wrong. They may stand behind what they claim and sell (or they at least itemize the product enough to allow the buyer to know what they are getting). I knew what I was getting, to some degree, but there was a surprise. A certification isn't a requirement to sell an electronic device in the US. But do we really want to trust a device that the manufacturer did not want a third-party to certify? Typically, certifications are noted on the device, along with clamping voltage. We see the UL certification here. But we see no reference to clamping voltage. Reasons bought The primary reasons this was bought was (1) for surge protection and (2) because it was UL listed. I also liked all the other bells and whistles surrounding the LED green light show of when a proper wiring connection or not so good wiring connection exists. But almost getting it is not the same as getting it This is not a “has-it-all” device. Where this also misses the mark is very important, which comes down to the most basic of functions for this device, its surge feature. So, am I Disappointed? Yes, here’s why. • Clamping voltage. What we have This is a Surge Protective Device (SPD), it is to serve an important role in protecting important electronics and equipment, in this instance, for an RV hook-up application. Lack of clear information is the key here in my disappointment. I had to go searching, but am no electrical engineer, to fully understand what I am seeing about surge protection, when it surrounds clamping voltage. More in a minute. The joule rating on the included specifications sheet is reported as being 4,200j. That’s nice. Those who know better say the joule rating should, at minimum, at least 1,000, and preferably 2,000. However, going well over 2,000 is strongly suggested, as in minimum 3,000, that is 1,000 per “leg” (i.e., prong) of that plug. Okay, we have four (4) “legs” (i.e., prongs) so we should have at least a 4,000-joule rating. Here, we have 4,200j, so that leg of the SPD protection sounds good to me. What is a joule rating The joule rating is how much excess energy the device can withstand before frying. Once fried from a surge larger than its joule rating, it no long protects anything. In addition, to my understanding, the joule rating is also a type of measure of life span. Over time, your suppressor (SPD) is going to take surge hits. The joule rating is also an indication of how long the suppressor will survive with all those hits - higher is better. To me, it’s like a bank account, being depleted over time, until all those joules are gone (spent) then that LED green light on the device no longer shows green. So, keep an eye out to see if that surge light is still on. Only half the surge story The joule rating is only half the surge story. The other half, and I think this is vital, is the pass-through voltage, also referred to as the clamping voltage, i.e., what is also further referred to as the Voltage Protection Rating (“VPR”). The preference is to pass through a lower number of volts to what is plugged in. Think about it, your RV is built to supply 120 volts to internal devices. Your RV may need more power to service whichever area of the RV, so multiple air conditioners. So, it may be taking in 240 volts. 120 volts may go to service one (1) part of your RV and the other 120v to another part. So, let’s think about this. Say the power company throws a switch that causes a huge surge in voltage, to 500 volts. How many volts will this suppressor allow through, to all your 120-volt devices plugged into your RV, say like your smart phone. Preferably, something a lot, lot less than 500 volts, to avoid devices getting fried. What clamping voltage does this have? Here, we have no concrete idea what that clamp-down voltage is, i.e., what excess voltage this device will slam the door on after allowing a value higher than 120 volts. Hmmmmm. There is NO reference to VPR in the specification sheet, there is a reference in the instructions that as part of this SPD’s operation, that their (Southwire’s voltage regulator should be positioned downstream this Surge.) So, I better go out to get that, because the last thing I want is below minimum voltage of and too many volts surging through. Some SPD’s have energy management systems (EMS) that would address this, but the cost factor is a significant multiple from this $$$ priced simple SPD. There is a WARNING The back of the device reads, in part: WARNING THIS UNIT IS A DIAGNOSTIC TOOL ONLY. IT DOES NOT PROTECT AGAINST MISWIRED PEDESTALS, DO NOT POWER RV OR WATERCRAFT FROM A POWER PEDESTAL WHEN A MISWIRE IS INDICATED IN THIS CASE, POWER PEDESTAL SHOULD BE SERVICED BY A LICENSED ELECTRICIAN PRIOR TO ANY USE Country of Origin Honduras Bottom-line: We appreciate all the bells and whistles this device has, but it’s missing what we also want. Disclosure is what we wanted, not guesswork and mystery. Our fault for not really looking into this device before selecting. So, we will only take a star off, we will look for another that describes clamping voltage. I hope my thoughts provided information.