Recent content by RonShap

ETap takes care of the conductor info for you, just tell it the size. The more important info is the installation characteristics. rho of the surroundings, spacing between cables/ducts, load factor, current

What code did you use to decide to put detectors in the corridors, electrical rooms, communication rooms? You need to refer to a code for all minimums, then you can always go over an above if you want. Minimums are generally in your adopted building code. If it happens to be the un-amended...

For underground ductbank calculations for ampacities, we typically use a rho of 55 for concrete and 90 for soil. We concrete encase our ductbanks, then cover with soil up to grade. We have the contractor send a submittal with lab tested sample / typical material that will be used around the...

It is convenient since the feeder is already there, but not required...

In both cases, the clearing time will be detection plus the clearing time of the primary protection device opening. The diff protection detection time should be the same as it seems the position of the secondary CT's are just either on the line side or load side of the 480V main. The...

Not a lot of use for them anymore since UL and the NEC require series rated testing of assemblies for determining the adequacy of an under-rated device downstream. I don't have that model in my library. Some still use them for control panel withstands. Is that your application?

Do a voltage check from Phase A of one transformer secondary to the other and you should measure ~0. Same for B and C, and if it is true, then parallel at will.

Any closed transition (milli-seccond or multi-second) should include both source contributions for short circuit calculations and arc flash if it creates worst case. Generally worst case for arc flash will be one source (lowest fault current).

To add the jreaf, if you have multiple generator set output breakers due to different load types (NEC Article 700, 701 and 702), 700 & 701 will have a different requirement for GF than 702. Also depends on the size of the generator and voltage. Check out 700.6(D), 700.27, 701.6(D), 701.26 and...

I'm trying to find a comprehensive reference for estimating connected and demand loads very early on in a new project based on VA/sf (or W/sf) I've used the very abbreviated list in IEEE 241 (old Gray Book) Table 15, but would like to find something more comprehensive and if nothing else, more...

LEED and NICET

Fire detection is typically placed per the locally adopted building code. If the adopted Building Code is based on the International Building Code, you will find the requirements in Section 907

Faults due to mice reduce based on voltage, since spacing between energized conductors are further apart.

For clarity, the US standards do NOT require an EPO for this application, as well as most IT applications. NEC Article 645 allows for leniencies that are not worth taking, even in a data center if you provide an EPO, all of which for sure do not apply to this classroom application.

I like this side by side comparison from Schneider http://www2.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/275000/FA275901/en_US/7300DB0401.pdf Keep in mind they make cast coil, so it may be a little biased.