Ieee std 45.7 question

[Savred22]

Under IEEE 45.7 PARA 5.6 it states "non-conducting guardrail protection shall be provided across the rear of all switchboards, even if removable rear covers are provided" .

My question is does anyone know any background information as to why this requirement exists or have had practical experience where the guardrail was used. The only scenerio I know of is when the rear covers are removed on low voltage switchboard during a thermal imaging survey which then the guardrail provides a barrier between the person and the live parts inside the switchboard.

 

[JoeStillman]

Sorry, my experience is limited to dry land.

Seems like a good thing to have if your switchboard is on a rolling deck.

 

[tom baker]

That standard is electrical installations on merchant vessels. We have a lot of varied experience here, but the NEC does not apply to ships and watercrafts. So be patient for replies.

 

[Jraef]

As I understood it fro when I did some marine switchgear projects, this all stemmed from Navy specifications going back to the earliest days of having electrical gear on warships. Think of having to walk next to something electrical while a ship is pitching and rolling in heavy seas. The guard rails are for safety of people near the equipment so they do not grab or place their hands on potentially energized parts or breaker handles, switches etc. Even if it is the rear of switchgear that is in the middle of the room, falling into a sheet metal cover can be dangerous because you can reduce the clearances inside and cause a flashover.