Instruction: Answer the given question using the supporting document.

Input:
Question: does anyone know the clamping voltage for this surge protector?
Document: APC site says of this unit:UL 1449 TVSS Rating 330VUL quit using TVSS rating after updating their spec around 2009 and it is obsolete. The specification now uses a higher current to measure the clamping voltage and the result is called VPR and will be a higher number than the older TVSS rating for the same unit. VPR is at least 400 for this unit (on the back of the unit).Look at Tripp Lite or some other reputable company.
The product was exactly as I expected, a big power surge suppressor that seems to be very sturdy. The power output is consistent so far, though I haven't had a chance to test it with a lightning storm yet. But I can say that the product is great so far. The downside is that the plugs are kind of hard to plug into, I don't know if its just my model but I do remember reading reviews about it.
My last APC SurgeArrest traveled thousands of miles across the country with me and saw many hotels. It finally reached it's surge arresting life as the red light remained on at all times. I picked this up as a replacement, now that I don't travel as much, the slightly larger size was worth having the dedicated plugs for those obnoxiously large wall warts. I know my electronics have an extra layer of protection when I plug them into this power strip.
#1 reviewed power strip with the most effective clamping power. Works exactly as it should and took the place of two older strips because the APC has a lot of room for larger plugs.
I'm just sorry I didn't know about APC before.
Don't listen to any of the 1-star ratings; they don't know what they're doing. This unit has covers for the outlets so you can slide them closed when not in use, so that's why some people's plugs might not "fit right" or whatever.The quality of this unit is the same today as it has been for the past decade+ in my experience.
This products works very well and came with an extra telephone cord and cable cord so you wouldn't have to buy extras. So far this has given me no trouble at all and the added benefit of this product being equipped with plastic covers on each outlet let's me know that there is safety for pets or children. All in all a great product .
My only complaints come from the unnecessary phone and coaxial inputs being included and the long/tedious process of registering these devices with APC. I personally know very few people who still have a traditional land line in their home and certainly haven't found the need to run my coaxial through this device prior to it going to my modem.
SIX BLOCK PLUG OUTLETS lol that's just insane compared to the competition. You can use a single one of these for your entire home entertainment center or computer complex! The best part (imo) is the overload light. It lets you know if you have too many things plugged into it, which is for YOUR safety and your equipment's safety, not for the unit's capacity.
I haven't had any subsequent mishaps, so I don't know if this thing works or not. I do know that the grounds in my outlets aren't the greatest (something this device told me about), but, when I connected the TV cable into it, that apparently added enough grounding for the device for it to then show that the fault was no longer present. We'll see. What convinced me about this item was how high the energy-handling capacity was, compared to almost any others I've seen.
Answer: The clamping voltage is 400v on L-N and 500v on L-G and N-G.  The clamping voltage is NOT 330v (best) as incorrectly listed in one popular review and on APC web site.  On close examination on their box, there is zero information given other then the Joules rating (which is the first clue something is afoot). If you open the box and check the back it lists the clamping voltage as listed above, not the 330 volt clamping voltage commonly misreported. PS clamping voltage and let through voltage are not the same thing. Clamping voltage is the max voltage let through (ie 330v with 330v clamping or 500v is it has 500v clamping (very poor)) let through voltage is the difference between the maximum allowable normal voltage (~170v) and the clamping voltage ie 330 on a good protector which would give you a let through voltage of 330-170= 160v over max normal voltage.    In conclusion APC website and popular review are not correct / and or misleafing. The surge protector offers poor surge protection. Loot for a better one with a 330 clamping across all three lines, has a high joules rating for longevity 2000+. There are other important factors, but those are the biggest two, and I don't  have the space to discuss further. Educate yourself and be warry of devices and companies that don't put their specs on the box as is the case with this unit/company.