Printed Circuit Board mounting requirement with boards that have exposed high voltage traces

[genlabs]

I am working within a project that involves access control and video, in a Georgia facility.
Another unrelated installer is using properly sized generic cabinets with steel backplanes.
I observed the low voltage components (logic controller, dry contact relay boards, etc) are being mounted with magnetic standoffs.
That is, the entire board can be pulled off the backplane and repositioned, if needed.
Seems like a novel approach for low voltage items.
When I saw the same standoffs being used with power supply boards my eyebrows started to raise.
The power supplies have "safe-to-touch" input blocks however those input blocks are soldered to the PCB and the bottom traces are fully exposed.
If the PCB was using conventional brass or nylon stand-offs this would not be an issue.
However the use of magnetic standoffs has me questioning the safety.
Although the magnets have good holding force I have to believe there is a written standard for this, especially when 120VAC mains is involved.

Do you know if this is a violation? Could you direct me to a document where this standard is published?
This situation can be corrected if necessary but I would like to have evidence in hand before approaching the installer.
Thanks!

 

[Spoon]

American regs are different to UK regs, so I can't give regs out for this instance.
You mention that the board is mounted in a properly sized generic cabinets with steel backplanes.
How do you isolate the supply to this cabinet?

We have some cabinets that have an isolator handle on the door, that is connected to an isolator on the backplate. To open the door you have to turn the isolator handle, which isolated the supply to the cabinet. The terminals of the isolator have shrouds on them so you can't touch them.

 

[genlabs]

I have installed cabs that require such power isolation before opening the door.
Those were 3 phase 480 volt cabinets though. Much more dangerous.
In this case the cabinet is only getting a single feed of 120vac.
There is no interlock or anything required on this arrangement.

 

[DPG]

I think photos will be needed. I can't picture this arrangement.

 

[Avo Mk8]

Do you know if this is a violation? Could you direct me to a document where this standard is published?
This situation can be corrected if necessary but I would like to have evidence in hand before approaching the installer.
Thanks!

i'm no longer working in this field so unfortunately don't have access to the various standards databases that can help you.
It's also complicated by the fact that you seem to be describing a bespoke build of equipment, not an already approved 'product', eg certified by Underwriters Laboratories.
There will be one or more electrical safety standards covering the equipment purpose, typicallly IEC/ ISO that get adopted / republished by ANSI and UL in the USA.

I see there is a generic standard NFPA 731 Standard for the Installation of Premises Security Systems.
which might be relevant, but itself is unlikely to deal with the minutiae of pcb mounting.

NFPA 731 sets standard on security installation ‘musts’

Chapters 4 through 9 cover the essentials of power supplies, intrusion detection systems, electronic access control systems, closed circuit TV systems, and more.

www.cablinginstall.com

The summary does say:
Chapter 4 looks at the fundamentals of security systems, including their power supplies, installation, wiring and integrity monitoring.
The standard states that all power supplies must be installed in conformity with the requirements of NFPA 70, National Electrical Code, for such equipment.

NFPA 70 might help you (equivalent of UK brown book), as far as principles are concerned, and might cover the need for insulation within the enclosure for safety? I don't have a copy any more! To refer to it you will probably have to buy or borrow a copy!