EC&M - Latest Comments

Re: Article 800: Communications Circuits

Steve McDowell — Wed, 24 Jun 2009 19:22:16 -0000

My understanding of a Plenum is if the HVAC is using the space above a ceiling or floor with no return duct to the airhandler. So above the ceiling you can feel the cold air. If it has a return duct system, this should be a non plenum environment. Is this correct. Please respond.
Thank you.
Steve

Re: Basics of Transformer Voltage Efficiency

tomad — Wed, 24 Jun 2009 15:24:31 -0000

What is no-load efficiency ? Based on the presented method (.. multiply output voltage by output current) which is zero for no-load, the effciency is 0 (zero).

Re: The Basics of Digital Multimeters

wlourina — Wed, 24 Jun 2009 11:26:57 -0000

How can I test the polarity of a 6 volt dynamo

Re: Code Calculations

Walt — Wed, 24 Jun 2009 01:23:16 -0000

To figure the voltage drop of a branch circuit, with three lighted signd on it, would you use the total combined amperage of the circuit? Or, can you figure the drop to the first light and than figure a new drop for the rest of the length with just the amperage from two lights, and then drop one more and figure the rest of the run with one?

Re: The Dish on Successful Satellite Installations

Art Williams — Tue, 23 Jun 2009 17:17:45 -0000

my building contains four ground level 1br apts. Present service is by CATV broadband cable company.. An attached control room houses heating elect, fire alam and 4 catv junction boxes.serviced by in- ground cable.If we installed a Dish network would it be possible to :Install one dish with identical progaming, to service the 4 apts.,disconnect CATV at junction boxes and use the boxes to transmit Dish signal to TV recievers.The purpose is cut down on 4 dishes to one dish.

Re: Sizing a circuit breaker.

Steve — Tue, 23 Jun 2009 13:11:25 -0000

I was told to size main CB's for fire pumps at 250%. Care to comment?

Thanks,
Steve

Re: Stumped by the Code?

jim long — Tue, 23 Jun 2009 11:20:45 -0000

what is the code reference for hospital grade m/c cable in patient care areas

Re: Code Basics

Steve Harrison — Tue, 23 Jun 2009 07:48:18 -0000

can a 480V motor control center be installed in a control room or lab which is normally occupied?

Re: The Basics of Electric Shock

WilliamThomas — Sun, 21 Jun 2009 23:44:46 -0000

I have an Electric Fence Charger designed to keep large animals inside an enclosed area. How can I reduce the "power" of the unit to deliver a weaker shock? Resistors on the connection coming hrom the "hot" lead?

Re: Stumped by the Code?

victor — Sun, 21 Jun 2009 22:27:08 -0000

what would be the size of conductor & protection of a 50 HP 380v 3phase fire pump considering the locked rotor current?

Re: Feeder Taps

Vilas Sawant — Sat, 20 Jun 2009 09:28:29 -0000

In an industrial application (only),

The code does use the the key word "only" which seems to be injected here for over 25 feet tap. What is the basis of this interpretation?

Re: Effects of harmonics on power systems

ismail — Fri, 19 Jun 2009 16:32:46 -0000

increase the tap changer

Re: Code Q&A

Mark Lyvers — Fri, 19 Jun 2009 13:24:11 -0000

So what methods of installation are acceptable to accomplish the 3 foot perimeter extension when there is no pavement or groundable material?

Re: Code Quiz

J Cox — Fri, 19 Jun 2009 07:50:19 -0000

Whats the min. restistance alowed by OSHA in alighting circuit?

Re: Code Q&A

E. Zifra — Fri, 19 Jun 2009 02:42:01 -0000

Mike,

I asume this also applies to an above ground swimming pool?

I believe 680 defines an above ground pool as permanently installed (same as an inground) if the depth of the water is 42 inches or greater.

In other words an above ground pool must have a equipotential bonding grid in addition to the bonding of the pool's metalic structure supports and filter motor?

Re: Stumped by the Code?

William — Thu, 18 Jun 2009 16:26:01 -0000

Is there a different cod e for industrial VS commercial applications? Define
live parts.

Re: Effects of harmonics on power systems

Jerry — Thu, 18 Jun 2009 15:21:41 -0000

Can you have too much filtering in a system?

Re: Code Quiz

David Schaefer — Thu, 18 Jun 2009 12:01:08 -0000

I have a question pertaining to explosion proof hubs. Does the 25% conduit fill apply to the sealing area or to the actual conduit the hub is attached to? CEC 2004 501.5 (c) (6)

Re: Code Quandaries

jesus deschamps — Thu, 18 Jun 2009 11:52:11 -0000

Type your comment here.

how do i size the generator for a small comercial ,,
supose it has air cond,
refrigerator
and so..

please make the answer step by step

Re: Should You connect Transformer Ground to Building Ground?

abbas_taweel — Wed, 17 Jun 2009 10:29:49 -0000

we have parcel dewelling.
designer so far did not give us any drawing concerning earth system .
he alleged that he can not provide the system with earthing loops till he gets the location of transformers.
is this true? or he can manage this loops separetely?
please reply

Re: Basic short-circuit current calculation

moorthy — Wed, 17 Jun 2009 03:29:18 -0000

What is the meaning of percentage impedance of transformer and how to calculate it?

Re: Preventive maintenance of motors and controls

Tahir Saleem — Wed, 17 Jun 2009 01:35:59 -0000

These are general reuirement ,need to include case history

Re: Wiring Methods for Industrial Machinery

Jason Jordan — Tue, 16 Jun 2009 09:45:08 -0000

Need direction. We're a industrial facility with 440V table saws. Can it be corded with a plug to a disconnect or doesn it need to be hardwired into conduit? Help would be appreciated.

Re: Installing Aluminum Building Wire

anthony — Mon, 15 Jun 2009 13:47:02 -0000

i recently did a job on a buildin where the brach circuits were ran in ac 90 aluminum. I was just wondering the allowable ampacity of this wire as the size of the conductos in the armoured cable was awg #14. The loads on the circuits remained the same as before as i only lowered the fusing saizes from 20 amps to 15 amps.

Re: Arc Fault Detection: Your Questions Answered

Marlon Burton — Sat, 13 Jun 2009 21:12:56 -0000

Are AFCIs required in kitchens? I live in Erie co. in Ohio.