<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Mark,<div>Thank you, your response is very helpful! How does the 120% rule get applied to the 1000A sections in my example? When grid connecting downstream on the load side of the switches on the 1000A sections do we ignore the rating of the 1000A bus bar being protected by a 3500 Amp Fuse? If yes what section in the code allows this?</div><div><br></div><div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div><p class="MsoNormal"><i><span style="font-size: 10.5pt; color: black; ">Al Frishman</span></i><span style="font-size: 13.5pt; color: black; "><br></span><span style="font-size: 13.5pt; color: rgb(3, 1, 0); ">Aeon</span><span style="font-size: 13.5pt; color: rgb(255, 151, 0); ">Solar</span><span style="font-size: 13.5pt; color: black; "></span></p><p class="MsoNormal"><i><span style="font-size: 10.5pt; color: black; "><a href="tel:%28917%29%20699-6641" value="+19176996641" target="_blank">(917) 699-6641</a> - cell</span></i><span style="font-size: 10.5pt; color: black; "><br></span><i><span style="font-size: 10.5pt; color: black; "><a href="tel:%28888%29%20460-2867" value="+18884602867" target="_blank">(888) 460-2867</a></span></i><span style="font-size: 10.5pt; color: black; "><br></span><i><span style="font-size: 10.5pt; color: black; "><a href="http://www.aeonsolar.com/" target="_blank">www.aeonsolar.com</a></span></i></p></div></span>
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<br><div><div>On Feb 17, 2015, at 10:23 AM, Mark Frye wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">
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NEC 2008, 240.21 (B)(1)(1) a.<br>
<br>
Each of the smaller buss sections are feeders which are sized
according to the tap rules. I believe the answer to your question is
that the larger fuse can't protect the smaller buss. <b>But</b>,
the likelihood of a short developing in that section of the circuit
is very small and if one did, damage to the equipment would be
limited that area. This is the essence of allowing taps.<br>
<br>
Mark Frye<br>
<br>
<div class="moz-cite-prefix">On 2/17/2015 6:17 AM, Allen Frishman
wrote:Wrenchers,</div>
<blockquote cite="mid:BE91068C-B519-4CBB-AA32-6C4372622C1C@aeonsolar.com" type="cite">
<div>I run into lots of Service Equipment that has a Large Service
Switch which feeds multiple Sections with the Bus bar on each
section rated significantly less than the main bus. A
specific example that I am currently looking at has a 4000Amp
Switch with a 3500 Amp Fuse which feeds 3 (1000 Amp) switchgear
sections. How is it possible that the 3500 Amp Fuse protects
the (3) 1000 Amp Sections? In this particular case each of
the 1000 Amp Sections has between 3 and 6 fused switches on
them. The sum of those switch/fuse ratings exceeds 1000 Amps
in each case. For reference - This service gear is over 40
years old. </div>
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<div>All thoughts are appreciated.<br>
<div>
<span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">
<div><p class="MsoNormal"><i><span style="font-size: 10.5pt;
color: black; ">Al Frishman</span></i><span style="font-size: 13.5pt; color: black; "><br>
</span><span style="font-size: 13.5pt; color: rgb(3, 1,
0); ">Aeon</span><span style="font-size: 13.5pt;
color: rgb(255, 151, 0); ">Solar</span><span style="font-size: 13.5pt; color: black; "></span></p><p class="MsoNormal"><i><span style="font-size: 10.5pt;
color: black; "><a moz-do-not-send="true" href="tel:%28917%29%20699-6641" value="+19176996641" target="_blank">(917)
699-6641</a> - cell</span></i><span style="font-size: 10.5pt; color: black; "><br>
</span><i><span style="font-size: 10.5pt; color: black;
"><a moz-do-not-send="true" href="tel:%28888%29%20460-2867" value="+18884602867" target="_blank">(888)
460-2867</a></span></i><span style="font-size:
10.5pt; color: black; "><br>
</span><i><span style="font-size: 10.5pt; color: black;
"><a moz-do-not-send="true" href="http://www.aeonsolar.com/" target="_blank">www.aeonsolar.com</a></span></i></p>
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