Flush-mounted electrical socket with USB - interior, minitest, thermal imaging (overheating test)

p.kaczmarek2 13 Mar 2026 14:01 24 1503 Cool? (+9)

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TL;DR

The LC-13-A flush-mounted single socket adds earthing and two USB charging ports in an 8.4×8.4 cm body that fits most fi 60 mm boxes.
Inside, two compact boards implement a flyback power supply with deep USB ports, a PL3368 inverter controller, and a 45R25P synchronous rectifier.
The USB output delivered up to 2.3 A at 5.1 V, while the transformer reached 70 °C and the controller hit 80 °C under load.
The socket works, but it gets quite hot, lacks QC support, and may run hotter in a real box than in the open test setup.
Its construction leaves only a few millimeters between the mains side and the low-voltage side, which raises concerns about cost-driven design.

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The LC-13-A is a flush-mounted, single electrical socket with earthing and two additional USB ports for powering/charging mobile devices. Its dimensions (width 8.4x8.4 cm, depth 4 cm) allow it to be easily installed in most fi 60 mm boxes. In this topic, I will test how it is built and investigate how hot it will get when operating under full load. I'll show the results in the form of thermal imaging camera images, so we'll also see which components heat up the most.

Wesa LC-13-A package: grounded socket with 2× USB, label with barcode

Indeed, this product is slightly deeper than typical sockets, it is worth checking the box before buying.

Unscrew the screw to remove the front panel:

Disassembled wall socket with USB: front panel, screw, and socket body with metal frame on a table

There are vents in the case, but I don't think they provide much - after all, it's sealed in a box anyway. The back of the case is on hooks, let's take a look inside.

Rear of a flush-mounted outlet with black housing and metal bracket on a white frame

The whole thing is cleverly built with two boards and deep USB ports. The manufacturer has made an effort to pack this efficiently into the available space.

Inside is a small power supply in flyback topology. The PCB is signed LB1223-BDUSB, but you can't see the chip markings. This will need to be unsoldered.

Close-up of a green PCB labeled “LB1223-BDUSB,” held between fingers

After unsoldering you can see an interesting design. Here we have on one side a path instead of a fuse and a rectifier bridge, and on the other side USB ports and a capacitor for 6.3 V, this is connected by a CY capacitor. The distance between the 'hot' and 'cold' side is a little worrying, it's only a few mm.

On the other side of the PCB we have two ICs - a PL3368 inverter controller and a 45R25P synchronous rectifier.

Flyback converter schematic with PL3368 IC, transformer windings, and rectified output stage

After visual inspection I soldered the whole thing back together:

Time for a load test. Up to 2.3 A at 5.1 V can be drawn:

Disassembled wall socket with USB ports and an electronic load module with fan and LED display

The thermal imaging shows nicely how even the warm air from the LD35 artificial load warms the table top:

Thermal image of an electronic PCB with a hot spot around 69.7°C and background around 20.5°C

Thermal camera view of electronics on a table; hotspot labeled about 70.0°C and a 19.2°C reading

Now the most interesting thing - the transformer heats up quite a bit, up to 70 °C, the inverter controller tops it, reaching 80 °C.

In summary , the socket does its job, although the USB does not offer the QC standard support required by most modern devices and in addition it gets quite hot, potentially even hotter than my tests showed, as I tested with the case removed and outside the box. The construction inside is quite economical, I was a little concerned by the small distance between the mains voltage side and the low-voltage secondary. It was also interesting to see how the transformer is built, but I didn't want to dismantle it.
Do you use this type of socket with extra USB?

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p.kaczmarek2 wrote 14389 posts with rating 12310 , helped 650 times. Been with us since 2014 year.

Comments

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Mateusz_konstruktor 13 Mar 2026 16:13

What is the claimed maximum current that can be drawn and is there any restriction on using both USB ports at the same time? [Read more]

p.kaczmarek2 13 Mar 2026 16:28

The product description mentioned 2.1 A at 5 V, so the USB power supply meets these parameters. Both USB sockets are connected together, so this current counts together. Once 2.3 A is exceeded, the voltage... [Read more]

keseszel 13 Mar 2026 19:28

Another piece of junk designed to extract cash from the naive. 80° in the can... health to electronics... [Read more]

cinepi 13 Mar 2026 20:55

One might be tempted to test how chargers from Kontakt Simon and OSPEL, possibly other Polish equipment manufacturers, compare with this marvel. I didn't expect any miracles from the VCX.... [Read more]

szeryf3 14 Mar 2026 18:17

By the looks of it, I already had the urge to buy one. Because it would be a very useful socket, but I'll wait to find something more secure for the phone for a couple of thousand. [Read more]

Alpha 15 Mar 2026 16:20

I assume that infrared measurements are taken under load, but I am also curious about the power lost in idle operation. In these times of global "electro-saving", such sockets with an inverter operating... [Read more]

CosteC 16 Mar 2026 05:59

Is the USB connected to PE? GND or the connector housing? It doesn't look like it, and it affects the evaluation of the distance between the secondary and primary side. Is the mounting frame connected... [Read more]

Jacdiag 16 Mar 2026 07:32

This scheme is AI generated :?: https://obrazki.elektroda.pl/7278242500_1773642590_thumb.jpg [Read more]

klamocik 16 Mar 2026 16:22

Sheriff..you have a phone for thousands and you want a 40 zeta power supply to protect you while you bathe.???. [Read more]

CosteC 16 Mar 2026 16:35

1) The price of the phone has nothing to do with the subject. 2) The power supply is supposed to be safe. No matter how much it cost. 3) This socket is not suitable for the bathroom for many reasons. 4)... [Read more]

klamocik 16 Mar 2026 17:06

So I'm just replying to you. [Read more]

p.kaczmarek2 16 Mar 2026 17:27

Ok will be tested. If you have any other suggestions please let me know. What do you think is wrong there? [Read more]

CosteC 16 Mar 2026 19:49

Drawn as if in painter by a beginner: Each coil different Primary ground symbols are different Ground after secondary Capacitors with connected covers Capacitors unpolarised but polarised. Missing... [Read more]

Jacdiag 16 Mar 2026 20:42

Complementing the above post.... e.g. missing the most important element - the USB socket & some "loose" dots [Read more]

p.kaczmarek2 16 Mar 2026 20:55

"Loose" dots mark the start of the windings - it matters, you can't reverse wind. And the USB isn't there, because it's from the inverter controller's datasheet. As for the rest of the criticism, I'll... [Read more]

keseszel 18 Mar 2026 08:53

Costec, you are clinging for the sake of clinging. Dots start windings, coils different because different wire thickness. Masses different because they are separated. That's my opinion. It looks like it... [Read more]

CosteC 18 Mar 2026 11:24

Exactly, such shitty ones. As long as I have lived, and I have lived long enough, this is the first I have heard of coils being drawn differently due to wire thickness. Please bring me the literature... [Read more]

keseszel 19 Mar 2026 10:43

If you think so then ok, I am not arguing. I was just looking at the diagram in that way. But I still think that such a socket is just plain, contrived rubbish and I wouldn't put it on. [Read more]

FAQ

TL;DR: The LC-13-A wall socket’s USB section delivers up to 2.3 A at 5.1 V and parts reached 70–80 °C under load; “both USB sockets are connected together.” [Elektroda, p.kaczmarek2, post #21861619]

Why it matters: This FAQ helps DIYers and specifiers decide if a flush-mounted socket with USB meets safety, performance, and fast‑charging needs in tight wall boxes.

Quick Facts

Form factor: 8.4 × 8.4 cm front, 4.0 cm depth; designed for Ø60 mm wall boxes. [Elektroda, p.kaczmarek2, post #21861619]
USB output: rated 2.1 A at 5 V total; both USB ports share the same rail. [Elektroda, p.kaczmarek2, post #21861720]
Measured load: stable up to about 2.3 A at 5.1 V; beyond this, voltage sags notably. [Elektroda, p.kaczmarek2, post #21861720]
Thermals (open‑bench): transformer ≈70 °C, controller ≈80 °C at full load (case removed). [Elektroda, p.kaczmarek2, post #21861619]
Fast‑charge: no Qualcomm Quick Charge (QC) support; charges as 5 V USB only. [Elektroda, p.kaczmarek2, post #21861619]

What is the LC-13-A and who is it for?

It’s a flush-mounted, grounded mains socket with two USB charging ports, aimed at users wanting integrated 5 V charging without external chargers. It fits common Ø60 mm boxes and suits light USB loads like earbuds or basic phones. [Elektroda, p.kaczmarek2, post #21861619]

How much current can the USB ports supply, and can I use both at once?

The USB section is rated 2.1 A at 5 V total. Both USB ports are paralleled, so they share one 2.1 A budget; pushing to about 2.3 A causes a noticeable voltage drop. “Both USB sockets are connected together.” [Elektroda, p.kaczmarek2, post #21861720]

Does it support fast charging standards like Qualcomm Quick Charge or USB PD?

No. The test found no QC support; devices charge at 5 V only. If your phone needs QC/PD to fast‑charge, expect slower rates from this outlet’s USB ports. [Elektroda, p.kaczmarek2, post #21861619]

How hot does the USB power supply get at full load?

On an open bench with the faceplate removed, the transformer reached about 70 °C and the controller about 80 °C during sustained load. Temperatures inside a closed wall box may run higher. [Elektroda, p.kaczmarek2, post #21861619]

Is installation depth an issue with this model?

Yes. At 4.0 cm depth it’s slightly deeper than typical sockets. Verify box depth and cable room before purchase to avoid fitment or heat buildup issues. [Elektroda, p.kaczmarek2, post #21861619]

Are there any safety design concerns noted in the teardown?

Yes. The reviewer observed a small separation—only a few millimeters—between the primary (mains) and secondary (low‑voltage) sides, plus a PCB trace used in place of a fuse. Treat this as an economy design choice. [Elektroda, p.kaczmarek2, post #21861619]

What power‑supply topology does it use and why does that matter?

It uses a flyback converter with a synchronous rectifier. This common, compact SMPS topology enables small wall‑box integration but concentrates heat in the transformer and controller under load. [Elektroda, p.kaczmarek2, post #21861619]

How do I quickly test if my wall USB outlet sags under load?

Use a 3‑step check: 1. Connect a USB load tester and set 2.0 A. 2. Measure voltage at the port; it should stay near 5.0–5.1 V. 3. Increase to 2.3 A and watch for voltage sag or thermal rise. [Elektroda, p.kaczmarek2, post #21861619]

What happens if I exceed about 2.3 A on the USB ports?

Voltage drops significantly and charging performance degrades. This is the observed limit where the outlet can no longer hold near‑nominal 5 V under load. [Elektroda, p.kaczmarek2, post #21861720]

Does ventilation in the faceplate help cooling in the wall?

Not much. The reviewer notes the enclosure sits sealed in a wall box; faceplate vents offer limited benefit compared with free‑air testing. Expect higher in‑box temperatures. [Elektroda, p.kaczmarek2, post #21861619]

Are branded alternatives worth considering?

A user suggested comparing Kontakt Simon and OSPEL USB modules. The thread didn’t test them, so verify specs, QC/PD support, and thermals before buying. See the comparison starter below for context. [Elektroda, cinepi, post #21861896]

Comparison: What did the thread test vs. what was suggested?

LC‑13‑A was tested; others were only suggested. Use this table to frame follow‑up testing.

Product	Tested in thread?	USB fast‑charge noted?	Thermal data noted?
LC‑13‑A	Yes	No QC	70–80 °C (open‑bench)
Kontakt Simon USB module	No	Not stated	Not stated
OSPEL USB module	No	Not stated	Not stated

[Elektroda, cinepi, post #21861896]

What did other forum users say about the heat?

One commenter criticized the high temperatures: “80° in the can… health to electronics…,” underscoring concern about heat in enclosed wall boxes. Consider derating and intermittent use. [Elektroda, keseszel, post #21861834]

Is this outlet a good fit for modern smartphones?

It works for 5 V charging but lacks QC/PD, so many modern phones won’t fast‑charge. For phones needing 9–20 V negotiation, choose PD/QC‑capable wall modules or use external PD chargers. [Elektroda, p.kaczmarek2, post #21861619]

What’s the simplest safe‑use tip to reduce heat stress?

Avoid running both USB ports near the 2.1 A total limit for long periods, and keep cables short to reduce I²R losses. Periodic touch checks can flag abnormal heat. [Elektroda, p.kaczmarek2, post #21861720]

What do key power‑electronics terms here mean?

See concise definitions below for flyback converter, synchronous rectifier, Y (CY) capacitor, creepage distance, and Qualcomm Quick Charge (QC). Each term is defined to help interpret teardown notes and safety comments. [Elektroda, p.kaczmarek2, post #21861619]

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