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 Post subject: Filler Bars & labels
PostPosted: Fri May 12, 2017 6:32 am 
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Joined: Mon Jul 26, 2010 10:55 am
Posts: 65
We have a situation where we are installing a 250v/200A fused disconnect downstream of a fused switch (same ratings) to allow for easier control of a panel at the end of the line. I'm wanting to simply use copper bus bar "3/16 x 1" in the disconnect and label it something like "NO OVER CURRENT PROTECTION PROVIDED". Does anyone have concerns/suggestions as to labeling this set up?

Thanks in advance.


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 Post subject: Re: Filler Bars & labels
PostPosted: Fri May 12, 2017 8:21 am 
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Location: Indiana
Uh, why?

I recommend going with a non-fused switch or installing fuses.

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 Post subject: Re: Filler Bars & labels
PostPosted: Fri May 12, 2017 12:16 pm 
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Nothing illegal about it. It's commonly done if you need to "convert" a panel from fused to non-fused. I've even seen some disconnects actually supplied that way for that reason from the factory.


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 Post subject: Re: Filler Bars & labels
PostPosted: Fri May 12, 2017 12:23 pm 
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PaulEngr wrote:
Nothing illegal about it. It's commonly done if you need to "convert" a panel from fused to non-fused. I've even seen some disconnects actually supplied that way for that reason from the factory.


Why would you need to do that? Curious.

A 200A switch is rated for 200A. What would be the harm in installing 200A fuses? A motor load I suppose that FLC x 1.25 is less than or equal to 200A but recommended fused OCP greater than 200A? That's about the only example I could think of.

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 Post subject: Re: Filler Bars & labels
PostPosted: Fri May 12, 2017 12:57 pm 
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Location: Rutland, VT
What is the fault current at that location? Typical non fused disconnects are rated 10kA but fused ones are rated higher. You may want to take that into consideration.

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 Post subject: Re: Filler Bars & labels
PostPosted: Sat May 13, 2017 8:25 pm 
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S&C sells one of their cutouts either with fuses or busbars. It's outdoor gear in most cases although plenty of equipment builders use S&C gear mounted in metal enclosed designs, too.

A nonfused switch might be "10 kA" but that's a fault rating. Same with the fused counterpart. At low voltage this single rating is all you get but with medium voltage switches it will list not only a rating that it can withstand but also the maximum allowable "break" and "make" fault currents as well. It's not uncommon to have say a 15 kV switch with a 12.5 kA break rating and a 20+ kA withstand rating. In this situation the switch would be destroyed by opening under fault currents (above 12.5 kA) but will survive high short circuit currents as long as a circuit breaker or fuse interrupts instead of the switch.


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 Post subject: Re: Filler Bars & labels
PostPosted: Sun May 14, 2017 9:43 am 
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True about the 15kV switches but the OP was specific on the voltage of 250V and non fused in that voltage is 10kA


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 Post subject: Re: Filler Bars & labels
PostPosted: Mon May 15, 2017 9:54 am 
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Location: Maple Valley, WA.
Just make sure that you are not "Modifying" the fused switch and converting it to a non fused switch. You could then void the UL label and cause the AHJ inspector red tagging it. In the State of Washington, all equipment must be UL labeled. Voiding a UL label by modifying it is not allowed unless it is re-evaluated in the field by UL or other approved companies.

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 Post subject: Re: Filler Bars & labels
PostPosted: Mon May 15, 2017 11:14 am 
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Food point about modifying. Using a roll your own slug might be considered a modification as well. Suggest using something made for the purpose. http://www.cooperindustries.com/content/public/en/bussmann/electrical/products/accessories/neutrals_.html


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 Post subject: Re: Filler Bars & labels
PostPosted: Tue May 16, 2017 4:01 am 
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stevenal wrote:
Food point about modifying. Using a roll your own slug might be considered a modification as well. Suggest using something made for the purpose. http://www.cooperindustries.com/content/public/en/bussmann/electrical/products/accessories/neutrals_.html


Yep. You could do that or you could just install a fuse:

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 Post subject: Re: Filler Bars & labels
PostPosted: Tue May 16, 2017 12:18 pm 
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Thanks for all the feedback. The fused disconnect was installed rather than the non-fused mainly because we had it. (Don't kill me, I'm just being honest.) With that being said also my NON-engineer belief was that putting identical fuses or even LPN to FRN of the same size in series like this is also not a good idea. So I'm sort of battling two beasts. Someone asked about AFC at the disconnect. It is currently about 22k but we are upgrading the upstream fuses to LPN's so I'm not sure how that changes things since the original model was with EON-200. With the filler bars installed I understand "voiding the UL listing" but I guess if I wait and get the proper parts from Bussmann that would fix that.

Thanks again. You guys never fail to make me think and learn something.


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