Do machine primary disconnects have to be switchable from outside the panel?

According to UL, NEC, OSHA, etc. Do machine primary disconnects have to be switchable from outside the panel? Or can I have a din rail mount disconnect, that you have to open the door to turn off?


Further for the Primary disconnect I assume it need to be a UL98 right?

You cannot do this per the following
2007 NFPA 79 - Electrical Standard for Industrial Machinery - this is the copy i have at home, work has the current copies
chapter 5 - incoming supply circuit conductor terminations and devices for disconnecting and removing power.
section 5.3.3 Requirements
5.3.3.1 (2) have an external operating means (e.g., handle) that complies with 5.3.4.
5.3.4 operating handle. sorry, too much to type.
hope this helps,
james

OK next question, If it is a permanently mounted machine. The disconnect can be in a separate box right? I don't have to actually put it inside the panel?

Specific to UL508A in the Industrial Machinery section, the disconnect must be within or adjacent to the control panel.

I believe NFPA allows up to 20' if accessable and in view of machine.

from 5.3.1.3
Exception No. 2: A supply circuit disconnecting means mounted in a
separate enclosure and interlocked in accordance with 6.2.4 with the
control enclosure(s) it supplies shall be permitted to be mounted up to
6 m (20 ft) away, provided the disconnecting means is in sight from the
control enclosure(s) and readily accessible to the operator. The control
enclosure(s) shall be marked indicating the location of the disconnecting
means. The disconnecting means shall be marked indicating the
industrial machine it supplies.

But 6.2.4 makes it sound like the enclosure doors need interlocks, with some exceptions. for lighting circuits and "memory elements and their support
logic requiring power at all times to maintain information storage
shall not be required to be interlocked with the control enclosure doors.
A safety sign shall be provided that meets the requirements of 16.2.4."

may i suggest that you get a copy. you can google for nfpa 79 and see if there is a current pdf out there somewhere.
section 5 tells you everything about disconnects.
summary.
5.3.1.1 tells you how to id the disconnect.
5.3.1.3 and 5.3.1.4 tells you about an external disconnect being mounted in the enclosure or IMMEDIATELY adjacent thereto.
sorry, there is to much to type.
james

James Mcquade said:

may i suggest that you get a copy. you can google for nfpa 79 and see if there is a current pdf out there somewhere.
section 5 tells you everything about disconnects.
summary.
5.3.1.1 tells you how to id the disconnect.
5.3.1.3 and 5.3.1.4 tells you about an external disconnect being mounted in the enclosure or IMMEDIATELY adjacent thereto.
sorry, there is to much to type.
james

Click to expand...

NFPA lets you read NFPA 79 for free. You do have to sign up for a free account which means giving them your email address. You can't download with the free version but it is the real version. I believe you can also look at previous version as well.