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 Post subject: Medium Voltage Safety Materials needed
PostPosted: Wed Jul 02, 2014 8:48 am 
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Location: Port Huron, Michigan
I have been asked to conduct "medium voltage safety training" for our electricians later this year. I am trying to find training resources to assist with this. I am willing to purchase the materials. I'm looking for something that would provide basic information that I could then restructure to meet our specific needs and then present to the electrical department.


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 Post subject: Re: Medium Voltage Safety Materials needed
PostPosted: Fri Jul 04, 2014 12:34 pm 
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Location: North Carolina
What is the highest voltage? Work methods change as voltage increases.


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 Post subject: Re: Medium Voltage Safety Materials needed
PostPosted: Sun Jul 06, 2014 5:39 pm 
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PaulEngr wrote:
What is the highest voltage? Work methods change as voltage increases.


This facility only works at 2400 V medium voltage. I'm struggling to come up with much that is much different than the LV (600 V in this case) that they are already used to working with.


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 Post subject: Re: Medium Voltage Safety Materials needed
PostPosted: Mon Jul 07, 2014 3:56 pm 
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In some ways 2400 V is not much different because effects like PD are not yet manifested.

Major differences:
1. Use a proximity voltage tester instead of multimeter.
2. Increased working distances.
3. Insulated cables are not necessarily 0 volts on the surface especially if unshielded which is common at 2400 volts in spite of NEC 2 kV rule.
4. Equipment is supposed to be accessible to qualified personnel only (internal) with some kind of tool, even keys.
5. Voltage rated gloves and/or hot sticks no longer optional.
6. Doors frequently bolted or sometimes have switches that trip off breakers...opening doors even for a look can induce a shutdown.
7. Working spaces around equipment start to grow instead of being constants.
8. Start to see equipment designed for working energized much more such as cutouts as opposed to makeshift like yanking fuses from fuseholders that is sometimes practiced on HVAC and lamp posts...no comment on acceptance of this work method.
9. Must maintain isolation. You will find a separate low voltage compartment on an E2 starter instead of an overload relay beside or under the contactor.
10. If you use shielded cable, do you ground one or both ends. Hint: there are times when this answer changes.
11. What separation distances to maintain to unshielded cable, height of insulators, and when/where to use higher insulation ratings.
12. Lightning arrester sizing, ratings, placement, jumper placement, etc.
13. Training class on making up stress cones, cutting insulation (no burrs), how to use tape if you use vinyl cambric and rubber, and so forth...however you do terminations so that the voltage stress doesn't eat up the ends. Definitely include removing semicon thoroughly which is sometimes missed.

Not sure about equipment specific considerations.


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 Post subject: Re: Medium Voltage Safety Materials needed
PostPosted: Mon Jul 14, 2014 9:02 am 

Joined: Mon Jun 09, 2014 9:19 am
Posts: 43
Our company hired EHazard out of Louisville, KY to train 6 employee's to become Electrical Safety Trainers. They trained us on how to do the low voltage and high voltage training. The course also included all the training amterials, and they update the materials for us at no cost when the revisions come out.
Thanks!


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 Post subject: Re: Medium Voltage Safety Materials needed
PostPosted: Mon Jul 14, 2014 9:03 am 
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1:Never (ever) just use a proximity detector.
Always use a contact voltage tester after using a proximity detector.

2:If you don't alreay know this subject material, (I am guessingthat you don't) then don't be the person trying to do the safety training for it.
If your management wants it done right they should be able to get some one in. I think Mr Phillips here does some of that, and I know ERS regularly does this for clients.
To minimize cost, you would wan't some one physically close to you.

Otheres may recommend on-line sort of training. I think "on line" safety training is just about worth the paper it isn't printed on.


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 Post subject: Re: Medium Voltage Safety Materials needed
PostPosted: Mon Jul 14, 2014 11:20 am 
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JKlessig wrote:
1:Never (ever) just use a proximity detector.
Always use a contact voltage tester after using a proximity detector.


Yikes! That would be most interesting to see done at 2400V and surely result in some sort of injury. I have never seen anything but a proximity detector used on over 1000V but perhaps I am not aware of new technology. Could you tell me what contact voltage tester you use at 2400V?

Thank you.


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 Post subject: Re: Medium Voltage Safety Materials needed
PostPosted: Mon Jul 14, 2014 7:42 pm 
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I've looked into options above 1 kv for voltage testing. IEC standards recognize 3 methods. There are capacitive meters (proximity testers). There are resistive testers, althoughI have never seen one. And there are permanent substation devices. The latter include various capacitive or inductive lights and I think ABB has a clever one with an LCD. These all must be on unshielded cable. If you are using elbow connectors, you can get them with capacitive taps.

There is one meter on the market that is a contact type that works up to 50 kv. Its the Biers PD50. I don't know of any others but phasing sticks are a contact-type "voltage sensor" but none give a rating like a proximity tester.

I agree with the comment about using a regular voltmeter to follow up with a noncontact meter. ALL cases reported by OSHA involve using a multimeter on a medium voltage system which resulted in initiating an arc flash. I know the basic problem is that proximity meters only work down to around 90 volts, but the fact is that residual voltages, often DC, can easily draw an arc on a "dead" line. Never mind induced currents. I have read about the practice of using a multimeter after a proximity meter in industrial establishments, but never seen a line crew do it and they have much more experience with safely working with medium voltage and especially induced voltages.


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