This is for anyone who is familiar with the NEC requirements for multi-wire branch circuits. The code sections in question is NEC 210.4. The question of using multi-pole breakers or handle ties to disconnect the ungrounded conductors of a shared neutral circuit or using dedicated neutrals is...
I have not been able to find a clear definition for what is considered "contiguous spaces" within a building. In a case I am looking at I have a secure corridor leading from a detention facility dorm sleeping area. All doors into the secure corridor or normally locked and closed including the...
I got a call from an electrician and building owner who had already started work to convert an existing 240/120 volt, three-phase delta service to 120/208-volt wye. The power company wanted to get rid of the old transformers and service and provide a new pad mounted transformer for the building...
I am working on an elevator modernization project. It is a hydraulic type elevator. This building has no fire protection sprinkler system. I have smoke detectors in the elevator lobbies and elevator machine room for elevator recall purposes. Usually when we have sprinkler heads in the...
This is an NFPA 70 and 99 questsion. We are having to add steam boilers for an Ambulatory Surgical Center. They are electrcally powered. The serve sterilizing equipment for the facility. Do these boilers have to be connected to emergency power?
I am not getting a good sense about the actual requirements for grounding the raised floor system. I've read about recommendations but not hard, fast requirements. In a standard raised floor application, no computer rooms or heavy data equipment, I would bond to any column, and bond every ten...
I recently specified a minimum 225-amp, 3-pole, 240 volt rated electrical contactor for a project. It's function is simply to remove power from a panelboard feeding cooking equipment under a kitchen hood when the hood fire protection system is activated. So there will be very little switching...
I am designing a job on which I specify a wireway and in the wireway splices for #3/0 600 volt rated conductors. It is a renovation where I show existing panel feeds being "intercepted" and refed from a new panelboard. I got to looking for some new splicing methods and really haven't found...
I have a hospital client who wants to replace a 480-volt, three-phase vacuum pump that they have had a lot of trouble with burning out motors and contactors. We discovered that the voltage a the motor is about 503 volts. Interesting enough the voltage at the service equipment is 500 volts. The...
I already have this on another forum here but think this is where it should be.
One of my clients has an Amprobe DM II Pro meter. This meter will measure the current and voltage of each phase and the reports will show phase voltages and currents; real, reactive and apparent power; and power...
One of my clients has an Amprobe DM II Pro meter. This meter will measure the current and voltage of each phase and the reports will show phase voltages and currents; real, reactive and apparent power; and power factor.
The amperage clamps are rated for up to 1000 amps and there is one for all...
I had a construction manager for a client get all bent out of shape because I suggested a 208-volt service for a couple of buildings for a project on which I was working. We were only in the schematic design phase for the project but based on what I knew, we did not need a 480-volt service for...
I went out to a jobsite today and some of the ditches in which the Contractor had installed underground conduit were still open. In the area of an electrical room one run of conduit had a 180 degree bend closely followed by a a 90 degree bend that turned the conduit up into the electrical room...
Here is the set up:
Medical duplex vacuum pump (alternting 10 HP motors) fed at 480-volt three-phase. Circuit parameters are 3-#8 & #10 G., 30-amp molded case circuit breaker. The pump is located in a boiler room which of course gets hot but we have not determined how hot. They only measured...
I have an issue with placing strobes in corridors. The codes that I have reasearched indicate that when a corridor changes direction, and specifically a right or left hand turn and not a T-intersection, you basically have a situation where your have an end to two corridors. In that case, you...
Does anyone know the logic of why a strobe is required within 15' of the end of the corridor? I have some ideas but has anyone ever seen an official explanation?
I recently put all of my light fixture info into an Excel spreadsheet. This works great. Excel has all kinds of built-in functions that work with Lists which is simply consecutive rows and columns with data. You can evoke all kind of simple sort and filter functions to reduce a large master...
For anyone that is using this program, I have a problem. I have a spreadsheet with multiple schedules that I have to link into autocad individually. It seems that when I try to link in the schedules that are in the far right colums of my spreadsheet, the program crashes. I get a "Run-time"...
I think I have read in some threads some suggestions for software that aids in linking and editing spreadsheets to AutoCAD. Can some of you offer software suggestions and a brief explanation of what it does? Thanks.
Setup:
Strip Shopping Center with a 208-volt, three-phase circuit, Main panel metered by the power company, wiring trough fed by main panel and owner installed meters to provide services to tenants.
One tenant is a heath club with receptacles that serve treadmills. On at least one receptacle...
