Crane Rail Disconnect location

[carlvant2004]

I would like to know what people think of locating a conductor rail disconnect switch inside of a guarded area.

Specifically, if the area is guarded by a fence.

The equipment in question would be:

#1 Automatic transfer vehicles that run on a traveling rail that has conductor rails on ground level. It is guarded by a fence. Can the disconnect switch be located inside the fence?

#2. Automated storage and retrieval machine on a traveling rail that has conductor rails on ground level. It is guarded by a fence. Can the disconnect switch be located inside the fence?

I do not see how this is readily accessible or safe.

I reference

NEC article 610 Part IV.
Disconnects shall be
1) Readily accessible.
2) Capable of being locked in the open position.
3) Open ALL ungrounded conductors simultaneously.
4) Placed within view of the runway contact conductors.

Article 100
Readily accessible : "Capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, and so forth."

Within view: "... the specified equipment is to be visible and not more than 15m (50ft) distant from the other"

 

[carlvant2004]

No Responses

No Responses

I have submitted this question to many forums and safety persons.

No one has commented.

My main concern here is the transverse hazard for the equipment. Entering the listed guarded areas with access doors with the only means to disconnect the runway conductor?s power inside the area seems logically unsafe.

Reference: OSHA 1910-29-212

Installers have asked for the exact rule for locating the runway disconnect outside the guarded area.

Does anyone know to whom I should write at OSHA to get an official ruling for this specific scenario?

Carl Van Tilburg
Electrical Engineer, PE

 

[muskiedog]

Contact your local - State OSHA if you have one for interruptations of the standards. You can also contact OSHA directly. Go to OSHA.gov and you will find all the information you will need to contact them either by phone or e-mail.

 

[dlhoule]

My main concern here is the transverse hazard for the equipment. Entering the listed guarded areas with access doors with the only means to disconnect the runway conductor?s power inside the area seems logically unsafe.

If it were left up to me, I would have one outside the enclosed area, but I would also have one inside. In most cases the outside one could be locked out before entering. In cases where you needed power on for troubleshooting it would be nice to have one accessible from inside the enclosure.

 

[petersonra]

I don't see a problem with it.

It is readily accessible by the very definition of that term. How is this any different than putting a piece of equipment, including the disconnect, in a secure room?

I don't see what is unsafe about it. The disconnect is there so you can lock out the energy to the equipment. It is not for any other purpose. There is no need to access it during normal operation.

 

[carlvant2004]

Anme B30.13-2003

Anme B30.13-2003

This is different than a simple locked room. The guarded areas in question have transverse moving large machines. You must get into the hazard to disconnect power. This is safe?

"Storage/Retrieval (S/R) machines and associated equipment"

States:

13-1.9.3 (a) "An Aisle disconnect means shall be provided between the power supply and the aisle contact conductor ... shall be accessible and operable."

13-1.9.3 (c) "A disconnecting means for an S/R machine or an aisle transfer car shall be provided in the leads from contact collector shoes or any other feeder to the S/R machine or aisle transfer car. This disconnecting means shall be accessible, ..."

Accessible (as applied to equipment). Admitting close approach; not guarded by locked doors, elevation, or other effective means.

There are two disconnects required.

#1. From Source to the runway.

#2. From Runway to S/R.

 

[carlvant2004]

ASME Standard Relevance

ASME Standard Relevance

There are no other specific S/R standards.

Therefore, ASME B30.13-2003 is promulgated under OSHA's "General Duty Clause"