Equipment local disconnect switch clearance 1

[napck]

I work in a shop where equipment is wired from a breaker panel to a local disconnect, 480vac 30 amp, then to the unit. The location of the disconnect is on the wall behind the machine. most of the machines are spaced 2 1/2 feet off the wall. Our in house safety person says that the expectation of clearance of a local disconnect is the same as the electrical panel that feeds it. I'm under the impression that clearance standards do not apply to local disconnects. We are starting a VPP program here and an OSHA inspector will be out to evaluate our site. My question is, do I need to have the electrical panel clearance at each local disconnect. We have a great deal more on conveyor motors and lifts. Which are near or at the motor, and depending on the motor location, not always readily accessable. Thanks, Mike

 

[waross]

not always readily accessable

This is usually a code violation in Canada.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[davidbeach]

NEC violation too. Those aren't panel clearance rules, they are electrical equipment clearance rules and disconnects are electrical equipment.

 

[DRWeig]

I'll give a third vote to match the other two.

Gotta be readily accessible and clearances are not limited to panelboards.

Good on ya,

Goober Dave

 

[rbulsara]

Agree too. Clearance is required in the direction of access for operation, that is in the front. See if you can "orient" the disconnect so as to have requisite clearance in front. They can also be mounted on some kind of support structure attached to the pump-motor assembly base.

Also "readily accessible" requirement is when there is a need to shut off power to service the "motor" and not necessarily for emergency stop for the machinery. So you need to clarify what you meant by not readily accessible, before you start pulling your hair out.

Rafiq Bulsara

http://www.srengineersct.com

 

[napck]

Not sure if I'm doing this right. But in responce to rbulsara, I'm going to include a picture of one piece of shop equipment and one conveyor motor local disconnect for your all's review. Let me know what you think. Thanks Mike

 

[jraef]

Lock-off devices such as that are not emergency stop devices, I see no problem with that. The rule for those is, "within clear sight" of the motor so that is a technician needs to work on the machine, he can have clear sight to see that his lock (LOTO) s in place before exposing himself to danger..

Come on guys, you're over engineering a bit here. The clearance issue is not for "any" electrical equipment. If it was, wouldn't a motor be "electrical equipment" then? The 36" rule has to do with having adequate clearance for anything where a door must be opened to access switches, devices, handles, disconnects etc. A Safety Disconnect Switch has the handle on the outside, the door does NOT need to be opened. Many millions of disconnect switches are mounted on the walls behind machine tools, it is totally impractical to imagine a structure in front of every drill press or grinder to maintain that 36" clearance. In fact, if a machine has serviceable motorized equipment in restricted spaces, the NEC REQUIRES a lockable disconnect inside of that that restricted space in 430.102(b).


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[napck]

I guess you can only attach one picture at a time. Let attach the picture of the shop equipment local disconnect for your alls review. This is the one that seems to capture the most feedback.

 

[jraef]

Clear article on the subject.
Upshot extraction:

Sections 110.26 and 110.34 of the NEC require working clearance in front of any equipment that may require examination, adjustment servicing, or maintenance while energized. This requirement, intended to allow an electrician to safely work on energized equipment, applies to switchgear, distribution panels, motor control centers, standalone motor starters, and most control panels. Required depth depends upon the operating voltage of the equipment, as given in Table 1. The clear space must extend from the floor to the greater of the equipment height or 6-1/2 ft, with a width equal to that of the equipment, but not less than 30 in.
...
TABLE 1. NEC required working clearance.

Voltage Required Clearance, ft-in.

Typical
Phase-Ground System Condition 1 Condition 2 Condition 3

0 to 150 208/120V 3-0 3-0 3-0
151 to 600 480/277V 3-0 3-6 4-0
601 to 2500 4,160V 3-0 4-0 5-0
2501 to 9,000 13,800V 4-0 5-0 6-0
9001 to 25,000 34,500V 5-0 6-0 9-0

Source: NFPA 70-2005.

"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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[DRWeig]

Good argument, jraef...

I can buy that if it's just a safety disconnect. I'd argue the other way if it was a combination device of some sort -- which turns it into a control panel if you stretch the definition a bit.

Posting the article is worth a star. It'll come in handy one day!

Good on ya and good weekend,

Goober Dave

 

[rbulsara]

I would side with your safety personnel. To me a disconnect requires examination and adjustment (operating the handle) while energized, it should have clearance when it is being operated by someone standing in front of it.

You can mount the disconnect high up and install a pull chains or hook sticks to operate it and that may meet the code without requiring clearance as you are not in front of it while operating.

Rafiq Bulsara

http://www.srengineersct.com