Bus Drop Attachment Plug Requirement

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jellison

Member
Gentlemen, I am in the process of planning moves for several machines in an industrial facility. Most of these machines will again move at least once or twice in the next 2 years. After reviewing this forum, the code including articles 368, 400.7 and 8, I see no reason not to wire each machine with properly sized protection, and a continuous Bus Drop Cable following the path below.

*Fused bus plug to
*Bus Drop Cable supported < every 8? to
*a suitable tension take-up support device
*attached to the building by an approved means
*same Bus Drop Cable installed as a vertical riser from the tension take-up support device to the equipment served
*strain relief cable grips provided for the cable at the busway plug-in device, support device and equipment terminations
*same Bus Drop Cable hardwired to an enclosed fused disconnect already mounted to the side of the machine

Is an attachment plug required on the equipment termination side? (seems redundant to the separate enclosed disconnect already mounted to the side of the machine) For some but not all machines I will need to prevent the transmission of vibration by using this method.

Thanks for your help and interpretations.
 

jerryalan

Member
Location
Perry, Mi. Shiawassee
Occupation
electrician
Bus Drop Attachment Plug

Bus Drop Attachment Plug

an attachment plug on the equipment termination side would facilitate your future moves and provide a source for a portable welder should one be needed.
i've always used plug and cord connections for presses whenever possible
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
101108-0819 EST

jellison:

I can not answer your code question.

However, I have a customer that overall in various plants probably has over a thousand machines connected via fused bus plugs to a 480 3 phase bus. Their installations are much like what you describe. These people are always moving their machines. Sometimes only a few feet.

Generally they provide a loop of several turns of the cable near the bus. This is to avoid having to rewire when moving the machine to a new position.

Most of the machines have an internal disconnect, quite often Sq-D, and the cable goes directly into the enclosure. No plug. Functionally no need for a plug and socket at the machine. If the machine moves to a new location simply unplug the fused bus plug, coil the cable, lay it on the machine, disconnect air, unbolt from the floor, bring in the forklift, and off to the new location.

.
 

Chev

Master Electrician @ Retired
Location
Mid-Michigan
Occupation
Retired Master Electrician, Formerly at Twin Lakes Electric and GMC
OSHA 29 CFR 1910.305(g)(ii) Flexible cords and cables may be used only for...(G) Connection of stationary equipment to facilitate their frequent exchange.
The way it is interpeted at our facility is that if it is to be bolted down to the floor, run conduit. If it has wheels it can have cord and plug. Another concern to address is the definition of "temporary". Temporary (where I work) has been relegated to mean if you're going to move it within a couple of weeks ok run Bus Drop. Any longer run conduit.
We used to do bus drop cables for feeds to small machinery, then OSHA came in to investigate an incident, and hit us with violations related to the above source. So our entire machine shop had to be redone in RMC.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
It appears your installation meets all the requirements of 368.56.
 

S'mise

Senior Member
Location
Michigan
OSHA 29 CFR 1910.305(g)(ii) Flexible cords and cables may be used only for...(G) Connection of stationary equipment to facilitate their frequent exchange.
The way it is interpeted at our facility is that if it is to be bolted down to the floor, run conduit. If it has wheels it can have cord and plug. Another concern to address is the definition of "temporary". Temporary (where I work) has been relegated to mean if you're going to move it within a couple of weeks ok run Bus Drop. Any longer run conduit.
We used to do bus drop cables for feeds to small machinery, then OSHA came in to investigate an incident, and hit us with violations related to the above source. So our entire machine shop had to be redone in RMC.

Sounds a bit contradictory. 1910.305 g says ok for frequent exchange, then osha says no? I believe you, I just don't see the violation was in 1910.305 g as you cited.

PS: I take "temporary" to mean 90 days
 

jellison

Member
Bus Drop Attachment Plug

Bus Drop Attachment Plug

Thanks for all your input, I will review the OSHA regs with our safety department.
 
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