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I have a device meant to be used inside electrical cabinets. It has a metal casing and is powered by 24V DC. It has three power connectors: 24V, 0V and PE.

I was surprised to find out that 0V and PE are shorted, as well as the metal casing. I was under the impression that this was not OK. Is this an actual issue or are they allowed to make such a device?

As a side question: is there anything to be gained by shorting earth and zero inside a device like this?


Edit: The actual device that got me to ask the question is a strobe controller IPSC2, currently owned by Mavis/Framos.

It's basically a programmable pulse current source for powering LEDs in machine vision. It doesn't really have a datasheet, but there is a manual on the original manufacturer's website:

https://www.smartek.vision/media/downloads/SMARTEKvision_StrobeController_User_Manual_v2_2_1.pdf

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  • \$\begingroup\$ Why do you consider PE to be an earth connection? something in datasheet? extra markings on the casing? A little more information about "device" would be useful. \$\endgroup\$ – Maple Mar 17 at 18:34
  • \$\begingroup\$ @Maple Because PE stands for Protective Earth. \$\endgroup\$ – relatively_random Mar 18 at 8:21
  • \$\begingroup\$ @Maple Referenced the device, if it matters. \$\endgroup\$ – relatively_random Mar 18 at 9:55
  • \$\begingroup\$ Yes, it does matter, a lot. IMHO the internal connection between the two is not acceptable. Only the casing should be grounded. Furthermore, some codes specifically prohibit grounding of the low voltage wiring (under 50V) used in pool lighting and similar installations. \$\endgroup\$ – Maple Mar 18 at 16:14
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enter image description here

Figure 1. The LED strobe controller is powered by 24 V DC.

I was surprised to find out that 0V and PE are shorted, as well as the metal casing.

That is a surprise.

I was under the impression that this was not OK. Is this an actual issue or are they allowed to make such a device?

I don't see why they wouldn't be allowed to make it but it should be clearly stated in the user manual. In fact, it's not even unclearly stated in the manual. There is nothing to give a clue.

As a side question: is there anything to be gained by shorting earth and zero inside a device like this?

No. It could cause a nasty surprise to the user.

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