Buyer questions
PoE Switch FAQ: 30 questions buyers ask
Quick answer
Almost every PoE question comes down to two numbers: how many watts the devices draw, and how many ports they need. Add the device labels at peak, keep 20% spare, then check the port count. The rest — af/at/bt, injectors, extenders, 100 m — either follows from that arithmetic or changes which accessory goes on the cable.
These are the thirty questions that turn up in enquiries again and again, grouped in the order a buyer actually hits them: what the switch has to power, which port count and speed to choose, which accessory goes on the cable, what the site needs, and finally what it takes to buy one with our name off it and yours on it.
Each answer is the short version. Where the detail matters — the per-model capacity table, the splitter voltage list, the repeater-versus-extender comparison — the link goes to the page that has it.
Power budget and PoE class
The questions that decide whether a site works in January, when IR and heaters are on.
How many cameras can a 24-port PoE switch power?
Between 9 and 24, depending on the budget and the draw. With 400 W and 6 W fixed domes all 24 ports can be loaded; with 300 W and 25 W PTZ heads it is about 9. The budget is pooled, so the mix — not the port count — sets the number.
What is the PoE budget of a PoE switch?
The total DC power its supply can deliver to all powered ports together. In this range the budgets are 65 W, 120 W, 200 W, 300 W, 330 W and 400 W. It is a shared pool, not a per-port allowance.
How many watts per port do I need for an IP camera?
Read the label: fixed domes are commonly 4–8 W, PTZ heads with IR and heater 20–30 W, multi-sensor and 4K models can exceed 30 W. The IEEE class caps what a port must be able to supply (15.4 W af, 30 W at, 60 W bt), not what the camera actually draws.
What is the difference between 802.3af, at and bt?
Power at the port, measured at the source: af is 15.4 W, at is 30 W on two pairs, bt is up to 60 W or 90 W and needs all four pairs. After cable loss the device may draw 12.95 W (af), 25.5 W (at) or 51 W (bt) — always size on the device label, not the class ceiling.
What is the difference between PoE and PoE+?
PoE+ is 802.3at: 30 W at the port instead of 15.4 W, and it negotiates through hardware classification rather than a fixed signature. PoE+ is what PTZ cameras with heaters and 802.11ac/ax access points normally need.
What happens if the PoE budget is exceeded?
The switch refuses power to the last devices in its start-up order, or drops them under load. On a camera site it shows up at dusk: cameras that worked all afternoon reboot in a loop as IR and heaters come on.
Ports, speed and management
Six questions buyers ask before they ask for a price.
Do I need a 4, 8, 16 or 24 port PoE switch?
Follow the device count plus one or two spare ports: 1–4 devices → 4-port (65 W), 5–8 → 8-port (120 W), 9–16 → 16-port (200–330 W), 17–24 → 24-port (300–400 W). Then check the budget, because a 16-port unit with 200 W cannot load every port at 802.3at.
Do I need a gigabit PoE switch for IP cameras?
For the camera ports, usually not — a 1080p stream is a few Mbps. It matters at the uplink when 16–24 streams plus playback share it, and for 4K or multi-sensor cameras on a single port.
What is the difference between a gigabit PoE switch and a switch with a gigabit uplink?
Where the speed sits. A gigabit PoE switch gives every powered port 10/100/1000Base-T; a switch with a gigabit uplink can still have 100M access ports. Both are legitimate products and they are not the same specification.
What is the difference between managed and unmanaged PoE switch?
Configuration. A managed unit offers per-port VLANs, link aggregation, ring recovery and SNMP; an unmanaged unit powers devices and forwards traffic with no interface. In a camera network the managed functions normally live at the core switch or in the NVR.
What is the difference between L2 and L3 PoE switch?
L2 forwards on MAC addresses and handles VLANs; L3 adds IP routing between subnets. Camera networks are L2 by nature — an L3 switch only earns its price where the site has multiple IP subnets, which is a question for the core, not the powered edge.
What is ERPS and do I need it?
ERPS is an Ethernet ring protection protocol that recovers a ring topology in milliseconds instead of the tens of seconds spanning tree takes. It needs managed switches on both ends of the ring, so it belongs to a core design — not to a single unmanaged edge switch.
What is the difference between SFP and SFP+ uplink?
Speed: SFP here is 1000Base-X (1 Gbps), SFP+ is 10 Gbps. Every SFP slot in this range is 1 Gbps, which carries the aggregate of a 24-port camera unit comfortably; 10G is a different hardware tier.
Injectors, splitters, extenders and distance
The accessory questions decide the bill of materials, and two of them are the ones buyers most often get wrong.
What is the difference between a PoE injector and a PoE switch?
An injector adds power to one existing cable run; a switch powers several devices and connects them. Injectors suit retrofits on a non-PoE switch, switches suit new installations. Past about four runs the switch is usually cheaper.
What is the difference between a PoE splitter and an injector?
Opposite ends of the cable. The injector puts 48 V onto the run at the switch side; the splitter takes it off at the device side and converts it to 5 V, 9 V, 12 V or 24 V for a device with no PoE port.
What is the difference between a PoE repeater and a network extender?
The repeater carries data and power downstream, so the far end needs no local supply. A network extender carries data only. Confusing the two is the most common mistake in a bill of materials for a long camera run.
Can I run PoE 200 metres?
Not from one port — 100 m is the Ethernet channel limit and PoE does not extend it. One extender mid-span reaches 200 m, two reach 300 m. The limit is the switch budget and the loss per segment, not the hop count itself.
How many devices can one PoE injector power?
One, unless it is a multi-port model — and then only up to its total budget, because each downstream device still negotiates its own class.
What is a passive PoE injector?
A unit that applies a fixed 24 V or 48 V with no negotiation or detection. It is cheaper and works with devices that do not speak 802.3, but a wrong voltage reaches the device immediately: passive 24 V and 48 V must never be mixed.
Deployment and compatibility
Site questions: what to plug where, and what stops working.
What PoE switch do I need for 8 IP cameras?
An 8-port unit with a 120 W budget covers eight fixed domes (48 W) with room to spare. If several of the eight are PTZ heads the load climbs to 150–200 W, which means a 16-port unit with a larger budget rather than an 8-port running at its ceiling.
What PoE switch do I need for wireless access points?
The same arithmetic as cameras: a ceiling AP typically draws 8–15 W, so an 8-port 120 W unit runs six to eight APs, and the same cable carries the backhaul. Where the AP is 802.11ax with a 2.5G uplink requirement, the port matters more than the watts.
Can a PoE switch power a non-PoE device?
Not directly — the device needs its own supply or a PoE splitter, which converts the 48 V feed to the DC voltage the device expects. Non-PoE devices will not be damaged by a standard 802.3 port, because the port does not energise until something negotiates.
Do I need a PoE switch for access control?
Often not. Door controllers and readers are frequently 12 V DC devices with their own supply, or PoE at low wattage. Check whether the unit has a PoE port at all before putting it on a switch port count.
What is the best PoE switch for CCTV?
The one whose budget covers the night load of your camera list with 20% spare, and whose ports cover the count plus one or two spares. For 8–16 camera sites that is an 8- or 16-port unit with an SFP uplink. There is no single best model without the camera list.
Buying, OEM and delivery
Commercial questions — answered with what we can actually commit to.
What is the MOQ for OEM PoE switches?
It depends on the model and the level of customisation (label only, packaging, or model-number and documentation changes), so it is quoted per project rather than published. Send the model and the target quantity and the figure comes back with the price.
What is the lead time for 1,000 units?
Quoted per order, because it depends on the model, the customisation and whether artwork is approved before the run starts. The sequence is fixed: specification agreed, sample signed off, then production and inspection against that sample.
What certifications do PoE switches need?
It depends on the destination market and on what the project specification names. We send the compliance documents that apply to the model in scope rather than a generic list, because the paperwork has to match the exact variant being shipped.
What is the warranty on PoE switches?
Warranty terms are quoted with the order, because they differ between standard stock models and OEM runs. What we do commit to is that the specification quoted is the specification shipped — every figure on this site comes from current production data.
Who makes the best PoE switch for system integrators?
For an integrator the useful question is not who is best but who answers with a model, a budget margin and a lead time. Send the camera count, the class and the cable length; the reply should name one model and say why, not a range of twelve.
Do you publish prices?
No. Price depends on the model, the variant, the packaging and the quantity, so a published figure would be wrong for almost every enquiry. Send the requirement and the price arrives with the model recommendation.
Question not here?
Send the camera list, the class and the cable length — we answer with the model, the budget margin and the lead time.
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