Would there be an issue with installing a new zig zag grounding transformer at an existing building 480/277 3 phase, 4 wire service? In order to obtain effectively grounded solar inverter to meet utility requirement, they are requiring a grounding transformer. It seems that having a connection...
Just Curious anyone's opinion in regard to FT switches for Relay output contacts for close permissives and trip circuits for breakers. I have noticed some Switchgear manufacturers provide an FT switch on both sides of the relay output contact, and other manufacturers provide an FT switch on...
If one has an open conductor fault on a medium voltage single phase overhead circuit (phase to neutral), then have a question;
Is the fault current or voltage level different between the two scenarios below where the circuit above feeds a single phase transformer with a 120/240 volt 3 wire...
finding typical X/R ratios for standard transformers is pretty easy to find, however, I cannot find any information on a typical autotransformer X/R ratio. Only data I can find is from a Siemens PSSE model report on a project with an autotransformer that claims the impedance (per unit) is 0 +...
Does anyone have a list of the aluminimum tubing manufacturers for substations in the U.S. market? I cannot seem to find any good information on manufacturing suppliers and technical specifications with google.
How should a surge arrestor be rated on an overhead 12kV, 4 wire grounded neutral system that drops the neutral halfway along the circuit and becomes 3 wire. Would it still be considered solidly grounded system at the end of the 3 wire line, or sized like it's ungrounded?
If the SEL-351 fails, the ALARM output contact goes to 1. Is there any condition of failure where the ALARM relay word bit would not go to 1 as well?
I.E. instead of wiring the ALARM output contacts of the SEL-351 into the trip coil of the circuit breaker (relay failure would trip the...
In order to minimize voltage drop, I want to start various motors in multiple steps.
Step 1: the largest motor will be started under no load (mechanical load will be zero).
Step 2: the second step will start the smaller motors, under full mechanical load.
Step 3: The last step will connect...
Does anyone know how NFPA 20 is adopted in New Jersey? Is it adopted via reference in the New Jersey fire code? And if so, is it adopted in its entirety or just specific sections that are referenced in the NJ fire code?
What IBC building classification would a pump building be? The building will contain a fire pump, water booster pumps and sewage pumps and will only be occupied when maintenance is required on the pumps.
I am looking at another engineer's design drawings for a warehouse facility and do not see any horn/strobes anywhere in the building. Is fire alarm notification not required in warehouses? From looking in the IBC I did not see any exceptions in section 907.9 for this type of building?
I am replacing an existing fire alarm panel with a new fire alarm panel and want to extend the existing fire alarm circuits to the new panel location. Is it acceptable to splice the existing fire alarm circuits? I vaguely recall somehwere that splicing fire alarm cable is not allowed but...
I have an underground water tank for the sprinkler system for a high school. There is a float switch which monitors the water level of the tank with a solenoid valve which opens to fill the tank when the water level is low. How do I tie this into the fire alarm system to initiate a trouble...
An owner has requested CMP-50 plenum communication cable. As far as I can tell, CMP-50 was a listing that was proposed to be added to the National Electric Code but was rejected for the 2002 code, therefore is it not a cable that should be used if it is not an acceptable listing in the NEC? It...
I have an elevator machine room elevated above the penthouse floor. The machine room contains the elevator controller, therefore I have shown the disconnect located next to the elevator controller to meet the National Electric Code requirement for the disconnect to be within site of the...
I have been told by a contractor that the fire alarm control panel cannot be located inside the main electric room, therefore he wants to move it to a nearby storage room. I cannot find anywhere in the NYC building code that this is true. Does anyone know if what the contractor says is correct?
Are fire alarm building plans required to show the zoning? If so, are these zones only for the notification appliances so that the fire alarm panel can evacuate only one part of the building if need be? (The system in question is a voice evacuated system).
Are smoke detectors required in paths of egress if the building is fully sprinklered? Where can I find the code and/or code section that talks about this?
I have a school builiding on a campus style school,that is going to be renovated. No part of the building will be in use during the renovation. Is it still necessary for the contractor to maintain an operational fire alarm system during the renovation process or is this not necessary since the...
