old 2 phase starter (personnel safety issues)

[capt_zap]

Anybody have any knowledge of PERSONNEL safety issues that I could apply to my justification of upgrading from old 2 phase(overload) protected motor starters to 3 phase(overload)starters. The electrical/mechanical justification is obvious, but in this case, not enough.

 

[rbalex]

Re: old 2 phase starter (personnel safety issues)

I'm making the wild assumption these are three-phase motors. In that case, three overloads are required by 430.37 unless you can show some other "approved means." Usually this means integral thermal protectors.

[Edit Add;] Usually, meeting Code is considered enough justification by OSHA.

[ September 23, 2004, 12:38 PM: Message edited by: rbalex ]

 

[don_resqcapt19]

Re: old 2 phase starter (personnel safety issues)

Bob,
Capt-zap, said "old starters". Prior to the 68 code, only 2 overloads were required for 3 phase motors. The code is not retoactive and the two overload starters can remain in use until they or the equipment they serve are replaced.
Don

 

[rbalex]

Re: old 2 phase starter (personnel safety issues)

Don,

The retroactivity of the NEC is up to the jurisdiction. It cannot be used for ex post facto prosecution, but FedOSHA can and does enforce it retroactively in the since that an "old installation" may be forced to comply with current standards under the "imminent danger" clause of 29CFR1903.13. While it is rarely exercised, that is mostly because of limited FedOSHA personnel. There is a similar clause in Section 80.9(B). (I already know Art 80 must be "specifically adopted," but the concept is already found in many municipal codes.) Part of the definition of "imminent" is an "indefinite" period of time; i.e., it could happen "anytime," but not necessarily immediately. That leaves a lot up to an AHJ's interpretation.

However; I still should have given the Capt a better answer. A relatively unknown fact is that overload heaters provide a substantial part of the short-circuit impedance for determining the interrupting capability of combination starters that use a instantaneous-only, molded-case circuit breaker (Inst MCCB) as the SC/GF OCPD. The phase without the O/L is in jeopardy if a short-circuit occurs on it. Such faults can and have caused serious injury and fires.

The IEEE/PCIC is currently deciding whether to write its own standard for even three O/L Inst MCCB combination starters. The "end-users" are dissatisfied with both UL and NEMA testing in this regard. They are concerned that an internal fault could occur somewhere between the MCCB and the O/L relay. Its unlikely but the potential forces with high available faults, can exceed the "without extensive damage" clause of 110.10. With a 2-O/L starter an external fault could also be a problem.

 

[capt_zap]

Re: old 2 phase starter (personnel safety issues)

Thanks Bob and Don,
I appreciate all info.
I think you are on to something. If I can some how get some hard facts/documentation on the idea that faults, that subject the non overload leg of the starter, effect the breaker in a way that is harmful to humans, then I believe I would have a home run here. I could gather this info and use 29CFR1903.13 and Section 80.9(B) to purchase new equipment. Any idea where I could find such facts/documentation? I am going to give MSHA shout to see if they have anything.

Thanks again,

Darrell Branson
Electrical Superintendent
Granite Construction Inc.

 

[rbalex]

Re: old 2 phase starter (personnel safety issues)

The FedOSHA regulations can be found here.

We usually deal with Parts 1910 or 1926, but Part 1903 is actually what establishes FedOSHA's enforcement authority.

The reference to 80.9(B) is in the 2002 NEC. Article 80 has been moved to an Appendix, in the 2005 edition.

As Don pointed out, the requirements for the third overload didn't appear until the '68 NEC. That's before my time (just barely ) with regard to documents I have available; however, if you PM me I can put you in touch with some of the IEEE/PCIC folks. I'm not immediately involved with that Task Group and you need to know everyone who is on it (at least everyone I know) has an axe to grind - so you may not get totally unbiased opinions

 

[don_resqcapt19]

Re: old 2 phase starter (personnel safety issues)

Bob,

That's before my time (just barely)

Same here. The only reason that I know is because about half of the plant where I am normally assigned was built in '66 and the original starters only have 2 overloads.
don

 

[petersonra]

Re: old 2 phase starter (personnel safety issues)

Originally posted by capt_zap:
Anybody have any knowledge of PERSONNEL safety issues that I could apply to my justification of upgrading from old 2 phase(overload) protected motor starters to 3 phase(overload)starters. The electrical/mechanical justification is obvious, but in this case, not enough.

Its been a LONG time since 3 phase starters came with only 2 overloads. I'd be inclined to think that replacing them with new equipment might be justifed on the basis of old age on its own.

I am aware there are some hypothetical cases where they might be less safe then starters with 3 overloads, but I am not so sure the very small additional risk justifies any huge expense, nor have I ever even heard any stories about the awful things that have happened because of having only 2 overloads. To be honest, this would be fairly low on my personal list of concerns safety wise.

If you are looking to replace them strictly on the basis of safety concerns you could just add external overload blocks and reuse the contactors. Then you could upgrade to 3 overloads without the expense of replacing the contactors themselves.

 

[iwire]

Re: old 2 phase starter (personnel safety issues)

Originally posted by petersonra:
If you are looking to replace them strictly on the basis of safety concerns you could just add external overload blocks and reuse the contactors.

That seems like a great solution.

 

[rbalex]

Re: old 2 phase starter (personnel safety issues)

Originally posted by petersonra:
...If you are looking to replace them strictly on the basis of safety concerns you could just add external overload blocks and reuse the contactors. Then you could upgrade to 3 overloads without the expense of replacing the contactors themselves.

I might be inclined to accept this solution if it weren't for the fact that starters with 2-O/Ls are also probably old enough to only have 10, 14 or 22kA SC interrupting ratings. I haven't seen a facility that old that hasn't also had SC availability creep. This is one of the most overlooked problems with system upgrades.

 

[petersonra]

Re: old 2 phase starter (personnel safety issues)

Originally posted by rbalex:

Originally posted by petersonra:
...If you are looking to replace them strictly on the basis of safety concerns you could just add external overload blocks and reuse the contactors. Then you could upgrade to 3 overloads without the expense of replacing the contactors themselves.

I might be inclined to accept this solution if it weren't for the fact that starters with 2-O/Ls are also probably old enough to only have 10, 14 or 22kA SC interrupting ratings. I haven't seen a facility that old that hasn't also had SC availability creep. This is one of the most overlooked problems with system upgrades.

but thats a problem that also affects a lot of other stuff. can't you just change the main fuses to deal with this issue?

 

[rbalex]

Re: old 2 phase starter (personnel safety issues)

Originally posted by petersonra:
but thats a problem that also affects a lot of other stuff. can't you just change the main fuses to deal with this issue?

Depends on how important coordination is. If this is a mining operation, as it appears to be from the MSHA reference, its d___d important.

[Edit Add:] You'd probably have a tough time establishing the "series rating" too.

[ September 24, 2004, 08:12 PM: Message edited by: rbalex ]