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Ztrain, A workbook would probably be your best bet. "Interpreting The National electrical Code" is one I use in each new update. There are other workbooks out there, but I'm more familiar with this one by Truman C. Surbrook and Jonathan R. Althouse. The...

qms006, The code used to say NO! on this one and it more than likely still says Nyet! I have wire nutted wires to short to reach a new lighting panel installation (in the panel), but your position is pushing the envelope.

peterandersen, In working with motors and meggering, our bottom line R was 1 megohm, anything less meant the integrity of the insulation was lost. The cables are not in such a harsh environment as the motor's windings. The one cable with the low reading does indicate something out of the...

Thanks Bob this will help in my studies!

majesus, Have you considered fusing it rather than trying to chase down a breaker? Fuses are much faster and of course keep the I squared T to less than half cycle. This may get your catagory classification smaller. Selective coordination may be a reason for the breakers to be slower at...

Jensen, The best I can do is ANSI 37.17 which part of it sets calibration points for these breakers. NEC may say 1 sec, but the manufacturer who uses ANSI or IEC may have to use their standards to pass qualification tests. Like many here I don't have the financial means to be able have these...

I made a mistake that should have been 30 cycles for 0.5 seconds.

Jensen, From memory there seems to be a UL or ANSI requirement of a 3 cycle limit. That plus the actual quenching of the arc could be the total 1 second limit?

bozzah, the 600 volt motor will let you have more options. Your VFD choices are more plentifull where the 4160v you have limited vendors and in replacing the higher voltage may require a longer down time. The safety of the technicians working on the higher voltage is more of an issue. the 600...

Electrician1, Sola/Hevi-Duty has a product,a Constant Voltage Power Conditioner. It is a do-all product that may take care of your problem. The UPS only helps with voltage sags, brown outs and power outages. CVPC's takes care of everything else, but a faulty ground will still bug you! Make sure...

Electrician1, DPC's skeptism of the harmonics burning of the mother board seems right. I would question if the DC supply is the old style 6 pulse or newer 12 pulse. The 6 pulse was terrible at producing 5,7 harmonics and at large magnitudes. The newer 12 pulse reduces these to a more managable...

Roobarb, I hope I'm not intruding,try this site.... www.arcadvisor.com and the site www.csemag.com. The cse site has a series called "The Art of Protecting Electrical Systems" it is a 31 issue? series. anyway they are on Part #13 at their site which is downloadable.I hope I have helped.

The neutral would be switched if there is considerable amount of Triplen Harmonics. This would be a result from a Delta-Wye transformer connection. The triplens are not cansuled in the neutral as other currents,but they add as much as 1.73 X phase current. Single phase computer systems are well...