<![CDATA[Mike Holt's Forum]]> http://forums.mikeholt.com en Sat, 21 Nov 2009 00:28:18 GMT vBulletin 60 http://forums.mikeholt.com/images/misc/rss.jpg <![CDATA[Mike Holt's Forum]]> http://forums.mikeholt.com Part wind start vs. inrush current http://forums.mikeholt.com/showthread.php?t=120092&goto=newpost Fri, 20 Nov 2009 23:11:36 GMT Received this from our engineer who is designing a pumping plant. He received it from sevice planner at poco.
"On the part wind setup that you will have for well motor , could you get me specs on it. Specifically, what the percentage it limits the inrush current at."
I assumed since it is part wind 50 -70 percent, or am I not understanding what they are asking? ]]> Electrical Calculations/Engineering wchild1520 http://forums.mikeholt.com/showthread.php?t=120092 680.40 Hot Tub http://forums.mikeholt.com/showthread.php?t=120091&goto=newpost Fri, 20 Nov 2009 23:06:32 GMT I need some help with installing a 2 person self contained hot tub. The unit will be sitting very close to the house and there is not much space. I... I need some help with installing a 2 person self contained hot tub. The unit will be sitting very close to the house and there is not much space. I have attached a photo. The hot tub will sit in the area where you see the ice chest. The hot tub will be installed on a gravel base. There are brick pavers surrounding the area. I intend to move the A/C disconnect to a new location away from the hot tub. I would like to run RNMC along the wall of the house and ON the ground to the GFCI disconnect for the hot tub. I would also like to run the A/C power on the ground in RNMC. 680.10 prohibits underground wiring with 5 feet horizontally unless installed in race way and buried. Does 680.10 prohibit using a raceway on top of the ground? Finally, I understand I will need to bond the vents, window frame and water pipe together. Finally, does 680.26, equipotential bonding, require that I install a grid in the gravel base and extend it 3 feet horizontally?
I apologize for these questions but I don't have a lot experience with 680.
Attached Images
File Type: jpg photo.jpg (81.8 KB)
]]> Electrical Calculations/Engineering Greg1707 http://forums.mikeholt.com/showthread.php?t=120091 Exit Light http://forums.mikeholt.com/showthread.php?t=120090&goto=newpost Fri, 20 Nov 2009 22:48:32 GMT I am installing exit lights in a drop ceiling using a bar box. The bar is rated for 20lbs. and the box is a metal octagon with 8/32 screws. I cannot... I am installing exit lights in a drop ceiling using a bar box. The bar is rated for 20lbs. and the box is a metal octagon with 8/32 screws. I cannot find any reason why I would need a seperate tie wire to support box. Is there a BOCA code? Anyone know if I need to do this? I don't believe the NEC code requires it. ]]> NEC eljefetaco http://forums.mikeholt.com/showthread.php?t=120090 Things you find on the basement steps http://forums.mikeholt.com/showthread.php?t=120089&goto=newpost Fri, 20 Nov 2009 22:46:25 GMT I guess they decided they can put the addition on the restaurant anywhere they want to. Image: http://inspectpa.com/images/IMG_7030.JPG So... I guess they decided they can put the addition on the restaurant anywhere they want to.




So much for overhead clearance with the addition.

]]> NEC ivsenroute http://forums.mikeholt.com/showthread.php?t=120089 Art. 675.8 Disconnecting Means http://forums.mikeholt.com/showthread.php?t=120088&goto=newpost Fri, 20 Nov 2009 22:42:06 GMT I'm looking for interpretations of 675.8(B) Main Disconnecting Means.
"The main disconnecting means for the machine shall provide overcurrent protection"

Does a UL98 non-fused switch wired to a fuse block in the control panel comply with this requirement? Or is the only acceptable solution a fusible switch assembly?

Thanks ]]> NEC Golf Junkie http://forums.mikeholt.com/showthread.php?t=120088 Subtransmission Vs. Distribution http://forums.mikeholt.com/showthread.php?t=120087&goto=newpost Fri, 20 Nov 2009 22:34:37 GMT I was wondering if there are any codes/regulations regarding the use of a subtransmission line as a distribution line. Also, if anyone has any... I was wondering if there are any codes/regulations regarding the use of a subtransmission line as a distribution line. Also, if anyone has any thoughts or concerns about this practice?

I work for a municipal electric department. Our subtransmission voltage is 23kv. Our distribution voltages are 4160, 12470 & 23,000. We have plans to use an existing 23kv distribution line to also act as the subtransmission line that will be feeding two substations.

Personally, I don't like this idea. But, I'm here to try and get some hard facts concerning this practice, whether positive or negative.

Thank-you! ]]> Electrical Calculations/Engineering joel034 http://forums.mikeholt.com/showthread.php?t=120087 GFCI Question as it applies to Massachusetts http://forums.mikeholt.com/showthread.php?t=120086&goto=newpost Fri, 20 Nov 2009 22:01:17 GMT I just had a job today that was an older house with no ground wires in the cloth romex wire. The customer wanted to update some kitchen plugs to... I just had a job today that was an older house with no ground wires in the cloth romex wire. The customer wanted to update some kitchen plugs to GFCI. Of course I suggested to run new circuits with ground wires and thats what I am doing. My question is could I have replaced the breakers with GFCI breakers and not run the new circuits. I don't know of any violation but I could be wrong. I know the GFCI breakers dont require the circuit to be grounded to operate. ]]> NEC jzadroga http://forums.mikeholt.com/showthread.php?t=120086 Required Receptacle Locations http://forums.mikeholt.com/showthread.php?t=120085&goto=newpost Fri, 20 Nov 2009 21:40:05 GMT I have 2 columns in a finished basement, they are 7" X 7" square and 10' from the wall. According to the NEC are receptacles required on the columns? ]]> NEC Semuskie http://forums.mikeholt.com/showthread.php?t=120085 Wadsworth circuit breaker http://forums.mikeholt.com/showthread.php?t=120084&goto=newpost Fri, 20 Nov 2009 21:28:32 GMT I am trying to find a new or reconditioned 2-pole 100 amp Wadsworth breaker. Is this company still in business? Is there an aftermarket subsitute... I am trying to find a new or reconditioned 2-pole 100 amp Wadsworth breaker. Is this company still in business? Is there an aftermarket subsitute that can be used? ]]> NEC Razzap http://forums.mikeholt.com/showthread.php?t=120084 <![CDATA[Ceiling Mounted TV's]]> http://forums.mikeholt.com/showthread.php?t=120083&goto=newpost Fri, 20 Nov 2009 21:21:44 GMT Are there any Code requirements regarding space that apply to ceiling mounted TV's. Someone mentioned to me there was a Code required space from the top of the TV to the ceiling. Is this correct? ]]> Electrical Calculations/Engineering Dynamite http://forums.mikeholt.com/showthread.php?t=120083 Cord connected device in a panel http://forums.mikeholt.com/showthread.php?t=120082&goto=newpost Fri, 20 Nov 2009 21:20:48 GMT Question: Does a small UPS sitting in the bottom of an industrial control panel need to be strapped down in some fashion (someone told me that by... Question: Does a small UPS sitting in the bottom of an industrial control panel need to be strapped down in some fashion (someone told me that by code it needs to be secured because it is a cord connected device)????

Details:
We are building a custom industrial control panel. So we will need to comply w/NEC article 408. The UPS is similar to what is used for a personal computer & monitor. Everything in the panel will be powered through the UPS.

Tear it up guys! ]]> NEC wireman http://forums.mikeholt.com/showthread.php?t=120082 Old Breaker ID http://forums.mikeholt.com/showthread.php?t=120081&goto=newpost Fri, 20 Nov 2009 20:14:46 GMT Does anybody recognize this breaker? I am looking to replace this with a GFI breaker if possible. Any thoughts? Other option is to re-stamp... Does anybody recognize this breaker? I am looking to replace this with a GFI breaker if possible. Any thoughts?

Other option is to re-stamp mounting plate so that a GFI outlet will fit, but the customer really likes the idea of having a GFI breaker...

Thanks in advance!
Matt
Attached Files
File Type: pdf enclosure.pdf (91.0 KB)
]]> Electrical Contracting and Estimating/Management mpross http://forums.mikeholt.com/showthread.php?t=120081 Feeder wire and breaker sizing 600A http://forums.mikeholt.com/showthread.php?t=120080&goto=newpost Fri, 20 Nov 2009 19:57:17 GMT Guys, I need some help. I have one of those bad projects that keeps coming back to me. The contractor purchased gear and wire and delivered it to... Guys,
I need some help. I have one of those bad projects that keeps coming back to me. The contractor purchased gear and wire and delivered it to the job site. The gear is not based on my design but on a previous job that they did. The job is a hotel and the circuit is a 208V branch feed for each floor. There is one circuit with two problems.

Here is the situation I need help with. I have calculated the load for a particular floor at 440 amps. The breaker in the MDP is a 600 A, and the wire the contractor supplied to use is 2 parallel 350 kcmil Al.

I would have selected 2 runs of 500 kcmil Al.

If the 2 runs of 350 MCM are run in seperate conduits the rating of the feeder wire would be 500A Table 310.16.

I went to the code to prove that the wire size was to small for the breaker size, but I have been unable to come up with a "chapter & verse" for my claim.

Articles 210.19(A)(1) and 215.2 only requires the conductor size to have an allowable ampacity size not less than 100% noncontinuous load + 125% of the continuous load. The 500A of the 2 runs of 350 MCM meet this requirement because the load is calculated at 440A.

If this were a service feeder, I would be able to say 230.90(A) requires the breaker to be sized at or below the allowable ampacity of the conductors.

Article 215.3 says the 100% noncont. & 125% cont. about protection, but adds Article 240. Now 240.4 says the conductors must be protected against overcurrent according to 310.15. I think I just found it!?

Since 500A is a standard breaker size, then I can't go up to the 600A breaker with this wire.

Does this all sound correct, or did I miss anything?


The other issue with this circuit is that the contractor wants to run the parallel conductors from the 600A breaker to the floor and then tap the conductors to feed 5 200A MCB panels. My initial reaction was that it could not be done without installing a 600A disconnect at each floor and coming out of the disconnect with 3/0 CU to each of the panels with 200A MCB's.

After looking at 240.21(B)(2) again it looks like I may be wrong on this point. The 3/0 would be rated at 1/3 of the 600A.

My original understanding was the the tap had to be 25' from the protective device, but this does not seem to be the case, and as long as the wire being tapped is properly protected, I can see that the 25' would start from the tap point.

Do I have this one right or wrong? ]]> Electrical Calculations/Engineering Ron Poehlmann http://forums.mikeholt.com/showthread.php?t=120080 GFCI in Generator http://forums.mikeholt.com/showthread.php?t=120079&goto=newpost Fri, 20 Nov 2009 19:50:56 GMT OK, I think I am 99.9% right on this but would like to see if I have missed something. This is a friendly disagreement between my boss and my self. ... OK, I think I am 99.9% right on this but would like to see if I have missed something. This is a friendly disagreement between my boss and my self.
Generators installed out doors. The gen. sets came with a factory installed GFCI recp. for the block heater and battery charger. The box and GFCI are installed inside the gen. housing. Now after a few year the GFCI's are going bad, Will not test with the button, trip out even with no load etc.. He says that we should replace with a standard recp. because there is something in code ( cant find it just now) that allows us to do that because the gen. sets are under supervised control. I say no. My argument to him is 1 code doesn't allow for this. 2 even if it is under supervised control that doesn't mean just because you have a key to the housing you couldn't get a hit if the heater shorted out and didn't trip the breaker. 3 the factory didn't install the "best" grade GFCI recp. to begin with so its time for them to fail.
I am trying to make him see that we should replace them with the GFCIs that are WP and of a commercial grade or just install GFCI breakers on the line that feeds the recp. That way we know they are not wet from blowing rain or dust and dirt. And they are not subject to the vibration when the gen.sets are running. Am I wrong? ]]> NEC ceb58 http://forums.mikeholt.com/showthread.php?t=120079 240 Volt corner grounded delta generator http://forums.mikeholt.com/showthread.php?t=120078&goto=newpost Fri, 20 Nov 2009 19:28:55 GMT Let's say I have a corner-grounded 240 volt delta (B-Phase is grounded) electrical service and a 240 volt delta generator. Need help with how to ground the two systems. If I bring a ground wire from the generator to the transfer switch and the same from the electrical service, I will have a unswitch phase. :confused: ]]> Electrical Calculations/Engineering Brian B http://forums.mikeholt.com/showthread.php?t=120078