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Recent content by robertb

  1. robertb

    De-energizing an Electrical System under load

    Under some possible failure conditions, parts of the electrical equipment may maintain a dangerous electrical charge even after the system has been disconnected from power for several minutes. If wiring is ever disconnected during operation there is an especially high risk of equipment...
  2. robertb

    The exit illumination requirements for an exit discharge

    "City /County Title 24, California Code of Regulations" states that "exit as defined is a continuous .... means of egress to a public way..." "Public way as defined is any street, alley or similar parcel of land essentially unobstructed from the ground to the sky... and having a clear width of...
  3. robertb

    Smoke detectors in beam pockets

    Article A-2-2.4.3 of NFPA 72-1999 provides the criteria for placement of heat detectors in beam pockets. Other articles specify "smoke or heat" detectors. Is it acceptable to use the referenced article to justify installation of smoke detectors in beam pockets? Thank you.
  4. robertb

    abandoned power conduits

    Rbulsara, I understand your irony. However the removal of abandoned wiring is a very important safety issue, especially in case of fire. In my case the modification of existing hospital requires installation of a lot of new conduits. The ceiling spaces are extremely congested and the...
  5. robertb

    abandoned power conduits

    Please help me to find reference in the NEC or other codes / regulations regarding removal of abandoned power wiring and conduits back to the nearest active junction box. Thank you
  6. robertb

    Photoluminescent Exit Signs

    Do not forget to specify the requirement of legal disposal of signs at the end of life.
  7. robertb

    Underground 33 KV cable burial/protection requirements

    farang1 Table 1, Case 8 of State of California Public Utilities Commission General Order #128 (Rules for construction of underground electric supply and communication systems") requires depth of 751-35000V supply cables and ducts to be 24" (minimum), above 35000V: 36". Fig.1 of the referenced...
  8. robertb

    Elevator recall and shunt issues

    LGENE, Please review "Interfacing Elevators and Fire Alarm Systems" by Merton Bunker. Yyou can find the article on Google. Bob
  9. robertb

    Branch Circuit Transfer Switching

    Please consider the following: Per Article 5-10.3.5 of NFPA 101-1997 (Life Safety Code) “…the exit signs shall be illuminated by the emergency lighting facilities.” Article 5-9.1.2 of Section 5.9 (Emergency Lighting) of NFPA 101 states that “Where emergency lighting is provided by a prime-mover...
  10. robertb

    Generator Grounding

    Per IEEE Std 142-1991, Chapter 1.6.3 (Multiple Power Sourcs) the system ground may be accomplished... 1) Each source grounded, with or without impedance 2) Each system neutral connected to a common neutral bus, which is grounded,with or without impedance. Different grounding arrangements are...
  11. robertb

    Help! neighbor put 2 500 lb propane tank 2" from our house

    Material Safety Data Sheet (MSDS) define propane as extremely flammable liquefied petroleum gas. Per article 500-3(a)(4) of the NEC propane is classified as Class 1, Group D. Table 7902.3-A of 2001 California Fire Code (based on Uniform Fire Code) states that the minimum distance from outdoor...
  12. robertb

    Area Classification

    At the same time we do not require 3'clearance in front of electrical receptacles.
  13. robertb

    Neutral Bonding Issue with ATS, Generator, and UPS

    Fieldy, Please inform whether the UPS has integral transformer and maintenance bypass. Regards
  14. robertb

    Electrical Room exit requirement

    Please note that electrical room may require fire rated walls, see NFPA 110-5.2.1 & 5.2.2; NFPA 75-appendix C, fig B-1; NFPA 13-5.13.11.
  15. robertb

    Parking structure lighting

    Hello, I have a case of eight story open parking structure next to a residential area. The lighting fixtures adjucent to building edges are with glare guards and located not close than 14' from edges. How to estimate glare on ground and other levels? I can obtain point to point illumination...

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