User Advisory
| Advisory Title: | Electrical Safety During Beamline Bakeouts |
| Advisory Number: | 17/Rev. 0 |
| Issue Date: | January 1, 2005 |
| Review Date: | Note: The advisory procedure and all ALS user advisories are undergoing a complete review that will not be completed until early 2008. Until that time, all current advisories and procedures remain in effect. |
| Current Info: | This Advisory is valid for two years from Issue or Review Date(s), at which time it is reviewed for relevancy and accuracy. Copies of all current user advisories are available at the ALS User Services Office, (510) 486-7745. |
Overview
All vacuum vessels intended for use at the ALS require extreme heating
(bakeout) before they may be used. The heat tapes or cords required
for the bakeout process can pose an electrical shock hazard if not
used properly. This advisory
is intended to establish guidelines for the proper selection, care,
and use of heating tapes and cords used during bakeout. This document
does
not replace
official Berkeley Lab and ALS procedures and policies concerning
electrical safety. For more information about these policies, refer
to Chapter 8 (Electrical
Safety) of Berkeley Lab ’s Health and Safety Manual, PUB-3000.
Bakeout Electrical Safety Guidelines
In order to optimize safety for personnel and equipment before, during, and after the bakeout process, please note the following:
- Use three-wire heating tape and cord systems.
Two-wire heat tapes and cords are inherently less safe than three-wire systems and can pose a hazard to personnel working around the energized heaters. - All vacuum vessels must be properly grounded before any bakeout.
Please contact the ALS EH&S Program Manager (ext. 7407) or the ALS Electrical Shop staff (Bldg 80A, ext. 4127) with any questions related to the proper grounding of equipment. - All heating tapes and cords must be powered with a GFCI-protected
circuit using a thermostatic control device or variac.
Chambers that are undergoing bakeout by a variac-powered heating device must be monitored on a regular basis to prevent overheating of either the chamber or the heating device. - All heating tapes and cords must be inspected before use in a bakeout.
Heating tapes and cords must be replaced if there are signs of excessive wear, fraying, or overheating. Any heat tape or cord with an AC plug that can be split into two pieces must have the plug replaced or glued together. - Read all of the manufacturer’s instructions before
the use of any heating device.
Some heating tapes and cords are not designed for use on electrically conductive surfaces and should not be used at the ALS. Glas-Col heating cords are an example of such a cord and may not be used at the ALS. Please read the literature supplied with your heating tape or cord. If you are unsure whether or not your heating tape or cord is approved for use at the ALS, contact the ALS EH &S Program Manager (ext. 7407).
The Users’ Storeroom in Building 7 (ext. 2896) has a supply of heating tapes and cords approved for use at the ALS.
For More Information
For additional information about bakeout safety procedures, heating tapes and cords, or other electrical safety issues, contact the ALS EHS Program Manager (ext. 7407), ALS Electricians (ext. 4127), the Beamline Coordination Section Leader (ext. 5527), or ALS Operations (ext. 4969).
| Approved by | Signed |
| Walter Barry, Electrical Engineering Group Leader | 12/07/2004 |
| Ben Feinberg, Division Deputy for Operations | 02/17/2005 |