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#83207 - 01/21/03 10:44 AM Magnetic Starters and OSHA
Mike Wescoatt Offline
Member

Registered: 06/17/01
Posts: 164
Loc: Cedar City, Utah
I thought I saw somewhere in OSHA that we were required or advised to have magnetic starters on power tools of 1HP or larger to prevent unintended startup on applying mains power to the tool. (Such as after a bandsaw blade is replaced) I can't find it now... does anyone know about this one??
It may not have even been OSHA but some other regulatory body. Thanks!!!
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Mike Wescoatt

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#83208 - 01/21/03 11:23 AM Re: Magnetic Starters and OSHA
lighthouse Offline
Member

Registered: 01/02/03
Posts: 141
Loc: philadelphia pa 19125
Mike Wescoatt..mike i found this article on magnetic starters starting up .nothing on osha yet.but a good article.
http://home.att.net/~waterfront-woods/Articles/magneticstarters.htm

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#83209 - 01/22/03 06:32 AM Re: Magnetic Starters and OSHA
JBD Offline
Member

Registered: 07/12/01
Posts: 599
Loc: WI, USA
Mike,

I think the requirement is for "low voltage release", where the equipment must be manually reset and restarted after loss of power, sometimes this is called "prevent unmonitored equipment startup". Simply having a magnetic starter is not sufficient to provide this protection. A magnetic starter must be wired with 3-wire control (i.e. momentary pushbuttons). This protection can also come from: a manual starter which includes a low-voltage release solenoid, a cord end GFCI that trips when the neutral is opened (i.e. Model 2500L from TRC), or a dedicated low-voltage protection device (i.e. Saf-Start from JDS Products).

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#83210 - 01/22/03 09:03 AM Re: Magnetic Starters and OSHA
Mike Wescoatt Offline
Member

Registered: 06/17/01
Posts: 164
Loc: Cedar City, Utah
Thanks JBD. Sorry about my poor choice of words; all of the motor controllers that I install use a magnetic starter and a control circuit of some sort, usually either START/STOP or MAN/OFF/AUTO and provisions for E-STOP loops.
Did you find where this requirement is??
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Mike Wescoatt

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#83211 - 01/22/03 12:03 PM Re: Magnetic Starters and OSHA
JBD Offline
Member

Registered: 07/12/01
Posts: 599
Loc: WI, USA
Mike,

In my opinion a maintained contact MAN/OFF/AUTO selector switch will not provide low-voltage release.

Try looking here for standards info: http://www.saf-start.com/

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#83212 - 01/23/03 07:50 PM Re: Magnetic Starters and OSHA
Mike Wescoatt Offline
Member

Registered: 06/17/01
Posts: 164
Loc: Cedar City, Utah
You found the answer in a round about way JBD...

1910.213(b)(3)

You are right about the MAN/OFF/AUTO hence the need for the E-Stop loop. These are not installed on any machine that would cause injury on unexpected startup. Only START/STOP will be installed on machines that would cause injury on accidental startup.

Even though this applies to woodworking machinery, there are many more machines that could use this requirement, and I know my employer will see it the same way. We have to keep in mind that the codes should be considered minimum design standards and can be improved on.

Thanks for the help!!!
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Mike Wescoatt

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#83213 - 01/24/03 04:27 AM Re: Magnetic Starters and OSHA
Redsy Offline
Member

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
I hate to be a nit-picker on terminology, but if I recall properly, 2-wire control provides "no-voltage release" and 3-wire control provides "no-voltage protection"

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