Question 1

Could someone please tell me whether this is only for 48V cameras as we have 12V. Thanks.

Accepted Answer

The PoE standard is 48V and all PoE switches (or PoE injectors/power supplies) (except some older models made before it was standardised), and the MokerLink 8 Port Gigabit PoE Switch  is certainly a fine example of a 48V  PoE switch.
The important thing to remember is that even if your camera takes 12V from a directly-connected power supply, if (and ONLY IF) it is also PoE compatible, then it will work fine with power over ethernet at the standard 48V. (That 48V  is then converted down, inside the camera, to the voltage it needs, but over longer and thinner cables, as the ethernet cables tend to be, it is far more efficient and easier to send higher voltage and lower intensity (mA) of current, to provide the power needed, then to send lower voltage and higher intensity mA)
If your camera is not PoE compatible, then the switch will identify that and will not send power down the Ethernet cable and you will need to use a 12V power supply

Question 2

What does the "extend" switch actually do, no mention of it in the manual?

Accepted Answer

"Context is King" and most words don't mean much in isolation. That applies to "extend" in your question. If you would like to , perhaps, rephrase the question, including the whole phrase with "extend" in it, then, more people would be in a better position to give aproper, correct reply. I had a quick look at the item's description, on the Amazon page andI could not find the "extend". 
I hope this helps

Question 3

Can i connect one uplink port to my nvr and the other to my broadband router to allow me access to my home cctv images on my ipad/mobile phone?

Accepted Answer

Uplink ports are special ports, normally used for up-linking "up the tree" or for stacking multiple switches together and if I had a choice, I would not use them for anything else.
Having said that, I will point out that speciality /technical literature says that "There are multiple other uses for uplink ports, and, in some instances, you can even use an uplink port in place of a normal port" so I believe that you should be able to use the configuration you mentioned, but unless  you are tight for downstream ports for your cameras and other devices, I would connect it like this:
Connect just one uplink port to the broadband router (which, from how you formulated the question, I guess also has the access point, probably built in or connected to it)
Connect a "normal" /downstream port  to the NVR and other downstream ports to the cameras.  That configuration will work.
I hope this helps

Question 4

Are the 'hangers' included suitable for rackmounting?

Accepted Answer

No

ASIN	B082KD85MY
Best Sellers Rank	8,746 in Computers & Accessories ( See Top 100 in Computers & Accessories ) 50 in Network Switches
Box Contents	1 x 5 Ports 100/1000Mbps PoE+ Switch, 1 x AC Power Cable, 4 x Screws with nuts, 2 x Hanger, 1 x User Manual
Brand Name	MokerLink
Case Material Type	Metal
Color	Black
Compatible Devices	Camera, Wireless Access Point, Computer
Country of Origin	China
Customer Reviews	4.6 4.6 out of 5 stars (2,321)
Data Transfer Rate	1000 Megabits Per Second
Interface	RJ45
Item Weight	0.85 Kilograms
Manufacturer	MokerLink
Manufacturer Part Number	POE-G041G
Maximum Power	78 Watts
Model Number	5 Gigabit PoE Unmanaged
Number of Items	1
Number of Ports	5
Platform	Not Machine Specific
Switch Type	Temperature Switch
UPC	786118199767
Unit Count	1 count
Upper Temperature Rating	55 Degrees Celsius
Voltage	230 Volts

5-Port Gigabit PoE Switch

Details

Details

Description

Specifications

Common Questions