Mean Well NEL-400-5 Power Supply
5V 80A · 400W exactly · 180–264VAC only · fan-cooled · no PFC

The NEL-400 Series: Three Voltages and an Honest 400W

The NEL-400 series is a short one — just three voltages, all sharing the same 80A current ceiling. Only the 5V model reaches the 400W the family is named for.

Efficiency climbs with voltage across the three models: 79%, 83%, 84%. Even the best of them, at 84%, is well below the 90% of the UHP-500-5 at the same 5V and the same 400W output — which is the practical cost of the simpler circuit. At full load the difference is roughly 76W of heat here against 40W on the UHP-500-5, and that difference is precisely why one design has a fan and the other has an aluminium plate.

The NEL-400-5 Input Range: 180–264VAC, and Why It Rules Out 115V Sites

This is the single most important specification on the page, and the one most likely to be missed because the model number and the output rating look interchangeable with a UHP-500-5.

What 180VAC as a low line actually costs you

• No 120V markets at all. The United States, Canada, Japan, Taiwan and Mexico run 100–120V mains. A NEL-400-5 cannot be installed on them. That is not a marginal derating issue — the supply simply will not start.
• Little margin on a nominal 220V supply. A 180VAC floor leaves 40V of headroom below a nominal 220V, or about 18%. On a site with a heavily loaded distribution board, long service drops or a generator, that margin can disappear during a brownout or a motor start.
• It sits close to a common 208V three-phase tap. A 208V line-to-line tap is only 28V above the minimum. Verify against the static characteristic curve before designing a 208V installation around this model.
• The static characteristic is not flat across 180–264VAC. The datasheet draws load against input voltage across that span, and the curve dips at the low end. A site running near 180VAC should be checked against that curve rather than assumed to deliver full load.
• Set-up and hold-up are only quoted at 230VAC. There is no 115VAC column to read because the model does not operate there — a small but telling detail that confirms this is a 230V-class supply rather than a full-range one.

NEL-400-5 Fan Cooling: 215 × 115 × 30mm, 0.85kg and No Aluminium Plate

The NEL-400-5 takes the opposite approach to heat from the entire UHP slim range. It has a built-in DC fan, and the datasheet specifies no mounting-plate condition at all — the mechanical drawing instead marks an air flow direction that the installation has to respect.

What you gain, and what you take on

• You gain freedom in the cabinet design. No 450 × 450mm aluminium surface has to be provided, and the unit does not have to sit flat against a thermally conductive plate. On a cabinet whose structure cannot serve as a heatsink — and that is a real constraint on many LED display frames — this removes the hardest installation requirement in the UHP range.
• You take on a moving part. A fan has bearings. In a fan-cooled supply the fan is typically the first component to fail, and its failure is quiet: the supply keeps working until the thermal margin is gone. That is the maintenance exposure the fanless range does not have.
• You take on an air path. The air flow direction is marked on the mechanical drawing for a reason. The intake must not be blocked, the exhaust must not recirculate, and the cabinet needs a route for that air to leave. A fan-cooled supply in a sealed cabinet moves hot air around rather than removing it.
• You take on contamination. Air carries dust and, in some environments, moisture and conductive particles into the unit. Fan-cooled supplies in dusty or humid cabinets need a maintenance interval that fanless ones do not.
• The derating curve still applies. Working temperature is −20 ∼ +60°C with output load derating, and the curve is drawn across that range. A fan does not exempt the supply from ambient limits — a 60°C ceiling is 10°C narrower than the UHP range’s +70°C.

How Many LED Modules Can One NEL-400-5 Power?

No supplier can answer this without knowing your module. The count depends on the maximum power rating of your LED module from its own datasheet, the number of modules on the supply, and the thermal headroom you leave — which here depends on the cabinet ambient and the fan’s air path.

1. Start from the real rating. 400W at 5V, which is 80A.
2. Apply a load ceiling. A common planning rule in LED cabinet builds is to keep continuous load at or below about 80% of rated output — roughly 320W, or 64A, on a NEL-400-5. This is an engineering convention rather than a MEAN WELL figure; confirm it against your own project’s thermal and warranty conditions.
3. Check the ambient against the derating curve. Working temperature is −20 to +60°C with derating, and the curve applies to the cabinet’s internal ambient, not the room temperature. A cabinet mounted in sun can sit 15°C above the outside air.
4. Divide by the module’s maximum power, taken from the module datasheet rather than a marketing page — full white is the condition a screen is commissioned under.
5. Check the current path. 64A still has to leave through a 9-pin terminal block and reach the modules. Confirm wire gauge, terminal rating and the number of feeds.
6. Confirm the mains supply actually stays above 180VAC. This is the step that is unique to this model, and it comes before the thermal ones.

Worked as an Illustrative Example — substitute your own module figures; these numbers are for the arithmetic only:

For the control and signal side of the same cabinet, the LED control system collection covers how sending cards, receiving cards and processors are powered and wired alongside the supplies.

NEL-400-5 Certifications: UL 62368-1 and EAC, and Nothing European

The compliance profile of the NEL-400-5 is markedly thinner than any other model on this site, and that is a statement about the product’s intended market rather than a criticism of it. It has to be read before the model is specified into an EU, UK or Australian project.

What is present, and what a European project needs

• UL 62368-1 is a genuine safety approval and covers the audio/video, IT and communication equipment safety standard. That is a real certification, not a self-declaration.
• EAC TP TC 004 and TP TC 020 are the Eurasian Economic Union approvals for safety and for electromagnetic compatibility respectively. A supply approved for the EAEU market is not thereby approved for the EU market.
• For an EU or UK project, the missing entries are the ones that matter. An EN55032 emission listing and EN61000-3-2 harmonic compliance are what a CE-marked installation is normally evidenced against. This datasheet provides neither.
• For a US or Canadian project the input range disqualifies it anyway. UL 62368-1 would be the relevant approval there, and it is present — but the supply cannot run on 120V mains.

MEAN WELL specifies this unit as a component to be installed into final equipment and states that the final equipment must be re-confirmed as still meeting the EMC directives. On this model that statement carries more weight than usual, because the component-level EMC evidence is limited to the EAC approvals.

NEL-400-5 Troubleshooting: Fan Cooling, the 180VAC Floor and Hiccup OVP

Two of the most common problems with this model are not faults at all: they are a supply that will not start on the wrong mains voltage, and a supply that keeps retrying by design. Work through these in order.

The supply does not start at all

• Possible cause: the mains is below 180VAC. This is the first thing to check on this model, before anything else, because the supply has no 115V mode.
• How to check: measure the AC voltage at the input terminals with the supply connected. Below 180VAC it will not run, and near 180VAC it will be at the edge of the static characteristic curve.
• Fix: connect to a 220–240V nominal supply. If only 100–120V is available, this model is the wrong choice and a full-range supply is required.

The screen dims or the supply shuts down as the cabinet warms up

• Possible cause: restricted air flow, not a faulty fan. The intake blocked, the exhaust recirculating into the intake, or two units stacked so one draws the other’s exhaust.
• How to check: measure the cabinet ambient and the temperature of the air leaving the unit. A large rise across the unit with a hot exhaust indicates the air is not being replaced. Confirm the fan is turning and that the intake is clear of dust.
• Fix: restore clearance on both faces per the air flow direction marked on the drawing, ventilate the cabinet, and separate stacked units. Then re-check the load against the derating curve for the actual ambient.

Output drops out and recovers on its own, repeatedly

• Possible cause: any of the three protections. Overload trips at 105–140% of rated power in hiccup mode; over-voltage is also hiccup mode on this model; over-temperature shuts down and self-recovers. All three recover automatically, so all three look identical from outside.
• How to check: measure DC current at full white and the cabinet ambient together. If the current is within rating and the unit is cool, the cause is more likely over-voltage from a load fault than a thermal or load issue.
• Fix: if current exceeds the planning ceiling, split the load. If it is hot, restore the air path. If neither, look for a load or wiring fault driving the output above the 5.6–7V OVP band.

A monitoring system reports the supply as failed when it is running

• Possible cause: a momentary protection trip that self-recovered. Because OVP on this model is hiccup mode rather than the latching shutdown used on the UHP range, a transient fault produces a brief output loss that a naive monitor reads as a hard failure.
• How to check: log the output over time rather than sampling it. A supply that recovers within a second or two and continues is behaving as specified.
• Fix: filter the monitoring logic for short interruptions, and investigate the underlying fault that caused the trip rather than the trip itself. Note also that this series offers no DC OK signal, so any status monitoring has to be built externally from the output.

The screen takes two to three seconds to come on after mains is applied

• Possible cause: nothing is faulty. Set-up is 2500ms at 230VAC with a 50ms rise — the slowest of the models in this set, against 1000ms on the UHP-500-5.
• How to check: measure the delay from mains applied to output stable and compare with 2500ms.
• Fix: no fix required if the delay matches specification. If control logic assumes supplies are ready sooner, adjust the sequence timing rather than replacing hardware.

Screen brightness drops or pixels discolour at the far end of a run

• Possible cause: voltage drop along the DC path, compounded by the wider regulation band. At 5V and up to 80A, cable resistance takes a proportionally large bite, and the output may already sit anywhere within ±3.0% before the run begins.
• How to check: measure voltage at the supply terminals and again at the input of the last module on the run. The difference is the drop, and the starting voltage is the other half of the problem.
• Fix: shorten the run, increase the conductor cross-section, or split the feed. Then set the ADJ control so the module input reads its specified 5V under load rather than so the supply terminal does. This model has no remote sense to correct the drop for you.

Mean Well NEL-400-5: Frequently Asked Questions