<![CDATA[Mike Holt's Forum]]> http://forums.mikeholt.com/ en Wed, 19 Jun 2013 03:05:11 GMT vBulletin 60 http://forums.mikeholt.com/images/misc/rss.png <![CDATA[Mike Holt's Forum]]> http://forums.mikeholt.com/ NFPA 70E - working in switchgear http://forums.mikeholt.com/showthread.php?t=154325&goto=newpost Wed, 19 Jun 2013 02:56:40 GMT Hello, We are planning to tie in feeder to one CB in a GE spectra switchgear. The switchgear has a bottom fed incoming service from a transformer... Hello,

We are planning to tie in feeder to one CB in a GE spectra switchgear. The switchgear has a bottom fed incoming service from a transformer (Allegheny Power) outside the building. The CB is a spare breaker that already been installed in the switchgear. The main is a 4000A, the CB is rated for 1600A. Our contractor is already ran all the cables and ready to connected to the lugs at the spare breaker.

A question arises concerning NFPA 70E. We have contractor put on the arc flash suit, We are planning to turn off the 4000A main, verify that all voltages on all phases are zero, lock out/tagout the main. the spare CB is three section away from the main (more than 48"). We are planning to take the back cover off to access the lugs on the spare CB.

Question is based on NFPA 70E, does the contractor have to wear arc flash suit when tieing in to the lugs while the main is off and lockout. My understanding is that the incoming services have barrier thus the buses will be isolated. The only section would have power would be at the main.

or do we just call Allegheny Powers and have them shutoff the xformer outside the building.

Thank you.

Francis. ]]> Safety francis.key19 http://forums.mikeholt.com/showthread.php?t=154325 Disconnect for wheelchair platform lift http://forums.mikeholt.com/showthread.php?t=154324&goto=newpost Wed, 19 Jun 2013 02:42:20 GMT Can a disconnect switch be located within a open shaft serving a wheelchair platform lift? The platform lift enters from a corridor and goes up to... Can a disconnect switch be located within a open shaft serving a wheelchair platform lift? The platform lift enters from a corridor and goes up to an open lanai area so the
shaft is open to the outside. The wheelchair platform lift equipment is located along the shaft wall. I'm being told that the disconnect must be located outside of the shaft
but per NEC article 620.51(C) it states "The disconnecting means shall be located where it is readily accessible to qualified persons". Since it is an open shaft, I believe
that qualifies as a readily accessible location. Am I correct? ]]> Electrical Calculations / Engineering New EE http://forums.mikeholt.com/showthread.php?t=154324 Bulbs keep burning out!? http://forums.mikeholt.com/showthread.php?t=154323&goto=newpost Wed, 19 Jun 2013 02:29:45 GMT I'm having a problem with a chandelier that is going through bulbs very quickly.

The first batch was Satco 60watt G16.5. Than I realized the box said to "burn base down" which these don't.

The second batch was Bulbrite 60watt G16.5 that say they can burn in either direction.

After these started to fail within a week or two, I tried Satco 40watt G16.5 thinking heat may be an issue. These didn't last long either. So now I have installed all new 5watt LED bulbs and one failed in 3 days and another is getting very foggy.

The chandelier has three sections with two bulbs in each. All 6 bulbs are in the base up position. One wire goes from the canopy to the center section then splits off to both ends. I believe all of the sockets have been affected. This is controlled by a dimmer and is on most hours of the day. I am getting 119volts at the sockets. Should I try removing and inspecting the sockets?

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]]> Lighting mike33 http://forums.mikeholt.com/showthread.php?t=154323 Good 1800rpm liquid generator http://forums.mikeholt.com/showthread.php?t=154321&goto=newpost Wed, 19 Jun 2013 01:36:54 GMT Hello, Can someone recommend a good 1800 rpm, liquid cooled generator? 10kw would probably be sufficient. Thanks, Hello,

Can someone recommend a good 1800 rpm, liquid cooled generator? 10kw would probably be sufficient.

Thanks, ]]> Photovoltaic Forum Ravenvalor http://forums.mikeholt.com/showthread.php?t=154321 UL250 Low Voltage Classification http://forums.mikeholt.com/showthread.php?t=154320&goto=newpost Wed, 19 Jun 2013 01:04:36 GMT What constitutes "low-voltage" for a home appliance, namely a refrigerator, in UL 250? ]]> General Electrical Forum Elektrotechnik http://forums.mikeholt.com/showthread.php?t=154320 Electrical induction question http://forums.mikeholt.com/showthread.php?t=154319&goto=newpost Wed, 19 Jun 2013 00:45:39 GMT I'm having trouble with a question in my apprenticeship if anyone can help me out it would be great.
The question is...
A 40V cable lays next to a 400v cable on metallic cable tray. Explain the magnetic and induction issues associated with this?
I can some what get the answer but i want full marks and a better understanding.
Cheers ]]> Electrical Calculations / Engineering carlf http://forums.mikeholt.com/showthread.php?t=154319 25 ohms to ground http://forums.mikeholt.com/showthread.php?t=154318&goto=newpost Wed, 19 Jun 2013 00:28:31 GMT How exactly do you go about testing to see if your ground rod is less then 25 ohms to earth? Put one lead on the rod and the other streached out and... How exactly do you go about testing to see if your ground rod is less then 25 ohms to earth? Put one lead on the rod and the other streached out and touching earth? ]]> General Electrical Forum olly http://forums.mikeholt.com/showthread.php?t=154318 overhead to undergroung http://forums.mikeholt.com/showthread.php?t=154317&goto=newpost Wed, 19 Jun 2013 00:23:39 GMT I am converting a commerical business from overhead to underground. Simply re-feeding It. It has an original CT cabinet feed by parralled 350... I am converting a commerical business from overhead to underground. Simply re-feeding It. It has an original CT cabinet feed by parralled 350 copper. This CT is tiny. My company does not want to have to replace this Ct cabinet. Is there any thing wrong with setting a big gutter above it and splicing on to the original wires? Im worried about a lug breaking and trying to fit this wire back in if I went straight to the CT. ]]> General Electrical Forum olly http://forums.mikeholt.com/showthread.php?t=154317 Surface mounting to concrete ceiling http://forums.mikeholt.com/showthread.php?t=154316&goto=newpost Wed, 19 Jun 2013 00:07:52 GMT I have a client who doesn't want a drop in ceiling in his office. I was wondering if I could simply surface mount with wedge anchors or if I need any additional support? ]]> Lighting bohl1076 http://forums.mikeholt.com/showthread.php?t=154316 Oil like residue in panel http://forums.mikeholt.com/showthread.php?t=154315&goto=newpost Wed, 19 Jun 2013 00:03:12 GMT I was working in a existing GE panel, remove breaker and about drop it. I had what seems like machine oil on my hand, alot of the breakers are... I was working in a existing GE panel, remove breaker and about drop it. I had what seems like machine oil on my hand, alot of the breakers are covered in it with some pooling on the side and at the terminal screw. I checked the wires entering thru the top and everything is dry, there is some oil on one of the feeders but only where wrapped in phase tape. I am concerned about a hazard there is enough to cause a problem. The panel is mainly A/C loads and have know idea what is causing this. ]]> General Electrical Forum KWH http://forums.mikeholt.com/showthread.php?t=154315 LB TOO SMALL ? http://forums.mikeholt.com/showthread.php?t=154314&goto=newpost Tue, 18 Jun 2013 23:33:14 GMT I came across a installation recently that I know has to be a violation but can't get to read the inside of the lb. There is a 2" Galv. conduit with 3 4/0 thwn and a #4 egc wires inside going to a crouse hinds short LB through a cinder block wall to another LB down into a disconnect. There is way to much bending in these lb's to not cause damage to the wires. Should I look for the cu in or number of conductors ? I also recall a 6x rule , would I use that ? thanks to anyone for the help. ]]> Electrical Calculations / Engineering hawkeye23 http://forums.mikeholt.com/showthread.php?t=154314 <![CDATA[Chiller MCA & MOCP]]> http://forums.mikeholt.com/showthread.php?t=154313&goto=newpost Tue, 18 Jun 2013 23:31:04 GMT Would a chiller with a nameplate rating of 920 MCA & 1000 Amp MOCP require the branch circuit conductors to be sized per nameplate MCA rating or would the conductors need to be sized per the 1000 amp MOCP per 240.4C? ]]> Electrical Calculations / Engineering gray roberts http://forums.mikeholt.com/showthread.php?t=154313 NEC 110.26(C)(2) http://forums.mikeholt.com/showthread.php?t=154312&goto=newpost Tue, 18 Jun 2013 23:24:28 GMT Is the 1200A equipment rating cumulative or any one piece of equipment? Is the 1200A equipment rating cumulative or any one piece of equipment? ]]> NEC clsarmiento http://forums.mikeholt.com/showthread.php?t=154312 Transformer Ho (neutral) connection http://forums.mikeholt.com/showthread.php?t=154311&goto=newpost Tue, 18 Jun 2013 22:58:48 GMT this may not be the best place to ask, but I'll start here!

We are having a new 2000kVA, 25kv/480-277, Y-Y transformer installed on an oil & gas site with both Xo and Ho bushings. Can someone comment on any codes or general practices about whether we should have the utility bring a neutral to the Ho?

At this point there may be some filtering systems installed on some small VFDs but I dont know for sure as I havent seen those onelines or bills of materials.

I dont know if there will be a need for this connection but am hoping someone can comment as stated on code requirementl for this connection, general practice or operational experience.

:dunce: ]]> Grounding versus Bonding huntr52 http://forums.mikeholt.com/showthread.php?t=154311 Cable Tray Sizing http://forums.mikeholt.com/showthread.php?t=154310&goto=newpost Tue, 18 Jun 2013 22:23:55 GMT Article 392.22(B)(1)(b) states that the sum of the cross sectional areas of all single conductor cables betweem 250MCM and 900MCM should not be... Article 392.22(B)(1)(b) states that the sum of the cross sectional areas of all single conductor cables betweem 250MCM and 900MCM should not be greater than the maximum cable fill shown in Column 1 of Table 392.22(B)(1). I have a situation requiring a separate equipment grounding conductor be carried back to a motor control center feeding 5 each 200HP motors. We are using single conductor cables to feed these motors. My question is this: Should the equipment grounding conductor for each motor be considered in the cable tray fill since it is not a current carrying conductor? ]]> Electrical Calculations / Engineering rolltide315 http://forums.mikeholt.com/showthread.php?t=154310