I'm a private consultant and I've been called in to do a design project. What I need to know is what is the national average price for a single lighting and power drawing?
Eric Kench, P.E.
I would remove the incomers and bus section switches and have separate enclosures with two automatic transfer switches connected in series. Notice I say in series and not in parallel. This ATS configuration would be connected between the bus and the sections. This way only one source at a time...
Why not just have one circuit breaker sized for both the load and the conductor in circuit CC1? Surely a 150A circuit breaker would protect a feeder sized for 225A if you chose to make it that large. NEC 430.31 to 430.63 describes Motor and Branch Circuit protection. Two different protection...
You're describing selective coordination. That's not what you have set up here. You have two circuit breakers in series. That 225A breaker is not feeding CC2 it's in the CC1 circuit. It does'nt seem to accomplish any real purpose. Selective coordination is when you have one main breaker feeding...
My only question is this. Why do you have two circuit breakers in series and why are they different ratings? Usually a main breaker would feed a minimum of two smaller breakers.
Eric Kench, P.E.
First of all you would have to determine the turns ratio. In this case it would be:
24,900/480=51.875 say 52
If the the short circuit current on the secondary is 32,000A then the primary Isc would be 32,000/52=615.4A
Eric Kench, P.E.
Well for one thing the tap is considered a grounded(or neutral)conductor and I don't think your supposed to have an OCPD of any kind in a grounded neutral circuit.
Eric Kench, P.E.
A three phase motor would not have a neutral. A single phase would have one like your house appliances that are motors plugged into 120 Vac.
Eric Kench, P.E.
In a three-wire delta system the phase currents add up to zero because there is no neutral. The voltages would be unbalanced and would not add up to zero.
In a four wire wye system the phase voltages would add up to zero assumming that the neutral connection has zero impedance and therefore...
Okay a new requirement in the 2008 NEC requires all the grounding conductors of communication circuits to be connected to an intersystem bonding terminal located at the service.
Eric Kench, P.E.
Yes you can run it inside a conduit but I don't think grounding is necessary. A telephone circuit is very low voltage and therefore not dangerous. The NEC does'nt seen to require it.
Eric Kench, P.E.
Also, article 330 of the NEC does not have any provisions for twisted pairs used inside type MC armour. Telephone cable is made up of twisted pairs. I've seen it installed inside conduit and ducts but never as an armoured cable. I think you would have to use a barrier because of the difference...
Just one question. Have you ever seen a telephone cable classified as Type MC? I never have. Do you know of a manufacturer that makes this type of cable? NEC 330.10 allows it's use as signal circuits but does this apply to telephone cable? There are other types of signaling equipment than...
According to NEC 501.115(B)(1) fuses in a Class 1 Division 2 must be installed in an explosionproof enclosure. The NEC does not make any provisions for fuses identified for Class 1 Division 2 locations. That's probably why you won't find it in any equipment catalog. However, if you find any...
