LED Screen Power Requirements: Amps, Breakers and Inrush

An LED screen’s power requirements are usually quoted as one wattage, but four numbers decide whether an installation works: AC current per phase, breaker rating and curve, inrush at switch-on, and voltage drop on the 5 V rail. All four follow from published 5 V supply datasheets.

LED Screen Power Requirements: The Short Answer

Quick answer: take the maximum DC load, divide by supply efficiency for real AC power, divide again by power factor for apparent power, then add headroom for cable and breaker selection. A non-PFC 5 V unit can pull nearly twice the input current of a higher-output active-PFC one.

A common planning rule in the Chinese LED industry adds 20%–30% headroom to the calculated screen load, documented by DAV Digital AV Engineering Network (dav01.com, 2020): convention for transient current and supply life, not a standard; the Mean Well 5V power supply range carries the units below.

The Three Formulas: DC Watts, AC Amps and Three-Phase

Three steps, one trap each. DC watts are 5 V times total module current at maximum brightness, the figure the power consumption calculation guide derives per square metre; real power is DC watts divided by efficiency; AC current is real power divided by voltage and power factor, the step where LED screen power requirements finally become amps.

1. Single-phase current: I = P_DC ÷ (η × V_AC × PF)
2. Three-phase line current: I_line = P_DC ÷ (η × √3 × V_LL × PF)
3. Apparent power for generator and UPS: S = P_DC ÷ η ÷ PF, in kVA

So how many amps does an LED screen use? A 10 kW DC load at 90% efficiency and 0.95 power factor on 400 V three-phase makes LED screen power requirements concrete: 11.1 kW real, 11.7 kVA apparent, 17 A per phase, and 32 A at 0.5 power factor.

Why Power Factor Changes Your AC Current

The LRS datasheets publish no power factor figure: the LRS-200, LRS-450 and LRS-600 tables list efficiency, AC current, inrush and leakage current only. RSP and UHP state PF>0.95 at 230 VAC and PF>0.98 at 115 VAC at full load.

The LRS-200-5 delivers 200 W at 5 V and draws 4 A at 115 VAC or 2.2 A at 230 VAC; the RSP-320-5 delivers 300 W on 1.5 A at 230 VAC, and the RSP-500-5 active-PFC unit is rated 450 W. A higher-output PFC supply draws less input current than a lower-output non-PFC one: apparent power, not output power, is the difference that decides the feeder size.

Cable and breaker are sized on volt-amperes, so a non-PFC design needs a larger feeder. The UHP-500-5 slim unit holds input current to 2.6 A at PF 0.95 full load.

Sizing the Breaker for LED Screen Power Requirements

Size the rating on steady-state load with headroom, then confirm the curve against the inrush peak. Many installation codes treat this class of load as continuous and require the circuit rated above the continuous current, so plan about 1.25 times the calculated current and round up to a standard size. Under the common IEC 60898 definitions, B-curve devices trip magnetically at 3–5 times rating, C-curve at 5–10, D-curve at 10–20.

Datasheet figures behind LED screen power requirements

5 V supply model	Rated 5 V output	Typ. efficiency	Power factor (datasheet)	Inrush at 230 VAC (cold start)	Hold-up at 230 VAC	Overload / over-temperature	Working temp.
LRS-200-5	5 V / 40 A (200 W)	87%	Not published	60 A	16 ms	Hiccup (self-recovering)	-25 to +70 °C
LRS-450-5	5 V / 75 A (375 W)	87%	Not published	60 A	16 ms	Shut down, re-power to recover; 3 min cool-down	-20 to +70 °C
LRS-600-5	5 V / 100 A (500 W)	86%	Not published	60 A	20 ms	Current limiting, shutdown after 3 s, re-power; 4 min cool-down	-20 to +65 °C
NEL-400-5	5 V / 80 A (400 W)	84%	Not published	100 A	20 ms	Hiccup; over-temperature self-recovering	-20 to +60 °C
RSP-320-5	5 V / 60 A (300 W)	83%	PF>0.95 / 230 VAC	40 A	8 ms	Hiccup; over-temperature self-recovering	-30 to +70 °C
RSP-500-5	5 V / 90 A (450 W)	84%	PF>0.95 / 230 VAC	40 A	18 ms	Constant-current limiting, auto-recovering	-30 to +70 °C
UHP-500-5	5 V / 80 A (400 W)	90%	PF 0.95 / 230 VAC	60 A	12 ms	Hiccup; over-temperature self-recovering	-30 to +70 °C

The LRS-450-5 is 75 A at 5 V, or 375 W, not the 450 W its name suggests, so sizing LED screen power requirements must read the 5 V row rather than the model name, a trap the 5V supply selection and headroom guide covers. The NEL-400-5 accepts only 180–264 VAC, so it suits 230 V sites rather than 110 V. The LRS-350-5 supply suits a feeder serving a few cabinets.

Breaker and inrush check for LED screen power requirements (Illustrative)

Circuit load	Datasheet input current at 230 VAC	Planning current with headroom	Breaker and curve	Magnetic trip window	Inrush assessment
1 × LRS-200-5	2.2 A	about 2.8 A	6 A, C curve	30–60 A	60 A at window top; 10 A C-curve gives margin
1 × NEL-400-5	5 A	about 6.3 A	10 A, C curve	50–100 A	100 A at window edge; use 16 A C or D
8 × LRS-200-5 on one feeder (Illustrative)	17.6 A combined	about 22 A	25 A, C curve, plus staged contactors	125–250 A	Above the window; energise in two or three groups
4 × RSP-500-5 spread over three phases (Illustrative)	about 2.1 A per unit	about 2.6 A per unit	10 A per phase, C curve	50–100 A	40 A per unit stays inside the window

A worksheet, not a design: the combined-current cells assume simultaneous energising, so verify on site.

Inrush Current: Why LED Screen Power Requirements Trip the Breaker

Cold-start inrush charges the input capacitors at switch-on, and it is the figure most often left out of the calculation. Table 1 shows the spread at 230 VAC cold start: 60 A for the LRS-200, LRS-450 and LRS-600 series against 100 A for the NEL-400-5. Those LRS input current and inrush rows are merged cells, so 60 A is a series value covering every model in the family, and the LRS-450 and LRS-600 series specify 35 A at 115 VAC.

Against the breaker’s magnetic window that peak decides: a 16 A C-curve device ignores anything below 80 A and trips between 80 A and 160 A, so one LRS-200-5 fits while three NEL-400-5 units switching together do not. Three measures control it: energise supplies in staggered groups; choose the curve deliberately, D where the peak is high and loop impedance allows, rather than a bigger rating that weakens protection; and spread groups across phases. The LEGIDATECH power supply range publishes its own inrush and PF data.

Single-Phase vs Three-Phase Distribution and Load Balancing

Splitting the load keeps LED screen power requirements within realistic conductor and breaker sizes. A 20 kW DC wall is roughly 25 kVA at 0.9 power factor: over 100 A on one 230 V phase, but about 36 A per phase on 400 V three-phase, which a 63 A board can feed.

Balancing is an engineering task: split supply groups by column and row so each phase carries a comparable DC load, and record it on the as-built drawing. Keep the neutral full-size with non-PFC supplies, whose harmonic current does not cancel like the fundamental. Cabinet wiring detail belongs with the indoor installation guide.

Voltage Drop on 5V DC Runs Inside the Cabinet

The 5 V side is where LED screen power requirements get unforgiving: a 5 V rail carrying 80 A loses 0.4 V across a single 5 mΩ connection, 8% of the rail. Modules seeing 4.6 V dim, shift colour and draw more current for the same brightness, so the fault looks like a data problem at first.

The same applies on the AC feed: a chained feed makes the first cable section carry every downstream supply and accumulates drop toward the end, while centre feeding in two halves roughly halves the current per section, as documented by the Chinese engineering account Guangdian Qianxian (WeChat public account, 2018). Feed each cabinet column from its own terminal pair rather than cascading the rail, and re-torque terminals after the first thermal cycle. Cable size comes from the ampacity table for the actual method and ambient temperature, not a rule of thumb.

Generator and UPS Sizing for a Temporary or Backup Supply

Generators are rated in kVA, so LED screen power requirements must be quoted as apparent power, with money attached: the 20 kW DC wall needs about 25 kVA at 0.9 power factor and 44 kVA at 0.5. Specify PFC supplies and confirm the set tolerates the inrush and step loads of the supply groups.

UPS ride-through is a separate calculation: hold-up at 230 VAC runs from 8 ms to 20 ms by model (Table 1), so a slower transfer switch drops the screen unless the UPS carries the load.

Worked Example: LED Screen Power Requirements for a 30 m² P6.67 Wall

An illustrative exercise with round numbers, not a product specification.

1. DC load. 30 m² at an assumed 600 W/m² maximum gives 18 kW DC, or 3,600 A at 5 V.
2. Supplies. At 86% efficiency and 100 A each, 36 LRS-600-5 units cover the DC side; 80 A UHP-500-5 units would need 45.
3. Real AC power. 18 kW ÷ 0.86 = 20.9 kW.
4. Apparent power and current. At PF 0.95, 22 kVA and about 32 A per phase on 400 V three-phase.
5. Breaker and feeder. 32 A × 1.25 gives 40 A per phase: a 40 A C-curve device per phase, 200–400 A magnetic window. One LRS-600 unit cold-starts at 60 A, far below that window, but 36 units still need staged groups.
6. Distribution. Twelve supplies per phase in three groups of four on staggered contactors, from a 63 A three-phase board.

A temporary version should be quoted at roughly 22 kVA plus margin for inrush and lighting. The P6.67 outdoor cabinet is the building block here.

Symptoms of an Under-Sized Supply

Under-sizing rarely appears as one failure: it shifts with brightness and temperature. Separate it from supply faults with the power supply fault diagnosis guide.

Symptom checks for under-sized LED screen power requirements

Symptom	Likely electrical cause	Where to check
Sections dim or reset when brightness rises	DC rail below the module minimum under peak load	Voltage at the far cabinet terminals under full white, not at the supply
Breaker trips at switch-on but never afterwards	Inrush peak against the breaker curve window	Curve type, group count, stagger timing
Screen restarts on scene changes	Transient current beyond supply headroom, or rail collapse on one group	Group loading against the 20%–30% planning rule
Supplies hot, output folding back in summer	Ambient temperature plus derating above the working temperature range	Cabinet temperature against the model’s working temperature
Discoloured or warm output terminals	Loose termination or undersized conductor at high DC current	Torque, terminal pairs used, conductor size for the installation method

LED Screen Power Requirements: Frequently Asked Questions

1. How many amps does an LED screen use? Divide the maximum DC load by efficiency and by power factor, then by voltage. A 10 kW DC load at 90% efficiency and 0.95 power factor draws about 17 A per phase on a 400 V three-phase supply, or about 51 A on a single 230 V phase.
2. What size breaker do I need for an LED screen? Plan the rating at about 1.25 times the calculated current, round up to the next standard size, then confirm the curve against the inrush peak. Small single-supply feeders are often 6 A or 10 A; multi-cabinet feeders land at 25 A to 63 A.
3. Can an LED screen run on single-phase power? Yes, until current becomes impractical. Beyond roughly 20 A to 30 A per phase, three-phase distribution reduces conductor size, terminal count and voltage drop for the same LED screen power requirements.
4. Why does the breaker trip only when the screen is cold? Cold-start inrush is highest when the input capacitors are fully discharged; repeated switching within a few minutes can also defeat inrush-limiting circuits, which need time to reset.
5. How do I stop nuisance tripping at power-up? Energise supplies in staged groups, choose the curve rather than a larger rating, and keep supplies per final circuit low enough that aggregate inrush stays inside the magnetic trip window.
6. Do LED screen power requirements change with brightness? Yes. Maximum brightness sets the design current and DC rail loading; average brightness at typical content sets the running current.
7. What DC voltage drop is acceptable on a 5 V run? Treat a few percent of the rail as the limit and measure at the far module terminals under full load: at 80 A a 5 mΩ joint costs 0.4 V, so terminals dominate.
8. Can I power an LED screen from a generator? Yes, if the set is specified in kVA with the correct power factor and tolerates the inrush of the supply groups. Non-PFC supplies raise the kVA requirement, so the generator gets larger.
9. Is holding time relevant to my installation? Yes, wherever there is a transfer switch or a UPS. Hold-up times of 8 ms to 20 ms at 230 VAC are short for LED screen power requirements, so a transfer longer than that will drop the screen unless the UPS carries the load continuously.
10. Should I use PFC supplies on every project? Where the feeder is long, a generator is involved, harmonic limits apply, or the neutral carries a large share of the load, active-PFC supplies are simpler. On a short single-phase feed with ample capacity, a non-PFC family remains practical.

Send Your Screen Specifications

Good LED screen power requirements start with the site, not with the supply. Send your screen specifications (overall size, pixel pitch, cabinet count, supply model, site voltage and phase, ambient temperature) and Excel LED will return the per-phase current, breaker rating and curve, inrush check and DC layout. For an open design, start from the Mean Well 5V power supply range.