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Improper Grounding and Bonding installations are responsible for 70% of fire and shock hazards according to the National Electrical Safety Foundation. This case study demonstrates "Objectionable Currents" when the equipment ground and neutral are improperly bonded, see article 250.6 page 70-103, NFPA 70, NEC, 2011 edition |
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Typical Electrical Problems with Design Build AED Projects
Fluorescent Light Ballasts Magnetic ballasts are not allowed. There have been many cases of magnetic ballasts producing enough heat (or arcing), igniting the plastic housing. Make sure lighting schedules and details show electronic ballasts. See Article 110.3, 90.4 NEC, 2008 edition.
Breaker/Conductor Selections Contractors have typically sized conductors for the load, and sized the breaker too large to protect the conductors. Review NEC 240.4. Check breaker/conductor selections to make sure that breaker protects load-side (downstream) conductor. There have been many cases of overloads that melt and ignite the insulation due to oversizing the breaker (or undersizing the conductor).See PDF’s Guide to NEC Mod 3, slides 18-22, Mod 7 slides 1-10; Code and Power Calculations Mod 2 Slides 3-20, Mod 3 Cable Trays Slides 19-30. See Article 110.14 and table 310.16 of the NEC, 2008 Edition
Exit Lights Check both electrical and architectural plans for exit lights. Contractors have been showing exit lights on both plans, usually with discrepancies. Review requirements in NFPA 101 paragraph 7.10 for Marking of Means of Egress. For more in depth requirements see EBook "Fundamentals of Electrical Design" at www.integforce.com
Grounding - Grounding plans and details are typically lacking. Review items such as Service Entrance, feeder, and grounding electrode requirements. Typically the design build contractors provide a grounding electrode system at every building, but no equipment grounding conductor back to the MDP with the feeder. See NEC 250.32(B), NFPA 70, 2008. See Grounding and Bonding PDF’s Mod 1 slides 10-14, Mod 3 slides 41-45, Mod 4 slides 14 – 32, Mod 5
Disconnect Switches Sometimes contractors omit disconnects. Review requirements of NEC 422, 424, 430, and 440 to see where a disconnect is required, or where the breaker is allowed to disconnect the equipment. See Article 404 NEC, 2008 edition, Article 100 definition of Readily Accessible, See Guide to the NEC Mod 9, Slides 8-11
Manholes/Handholes Have contractor number each manhole and each handhole. It takes the designer little time, and eliminates a lot of confusion in the field. See Article 110.22 and 26 of NEC 2008 edition
Receptacles Make sure designer uses GFI (or RCCD) where required by code. See Article 210.8 NEC, 2008 edition, PDF Guide to NEC Mod 5 Slides 5-11 10mA is the lowest European trip rating available- do not allow 30ma even if it’s written in the RFP
Fire Alarm and Detection System
90 degree Conductors Applicable codes (IBC, NFPA 101, UFC 3-600-01) generally do not require complete smoke detection systems. However, these codes also assume that a sprinkler system is also provided. Past RFP ’s have required smoke detection systems, and contractors generally have provided complete smoke detection systems. At worst these systems are stolen or vandalized; and at best they are not maintained. Current guidance from CSTC-A (customer for Afghan National Security Forces Projects) is to omit Fire Alarm and Detection Systems from Afghan-occupied buildings. Contractors will try to use 90 degree conductors to achieve more ampacity with a smaller wire diameter. Use 75 degree table in NEC Table 310.16 because terminations are generally limited to 75 degrees. Review NEC Art. 110.14(C). See PDF’s Guide to NEC Mod 3, slides 18-22, Mod 7 slides 1-10; Code and Power Calculations Mod 2 Slides 3-20, Mod 3 Cable Trays Slides 19-30. See Article 110.14 and table 310.16 of the NEC, 2008 Edition
Chinese light fixtures These generally melt and are a fire hazard. Products made in Europe are higher quality. Look for CE and/or IEC ratings. See Article 110.3, 90.4 NEC, 2008 edition
Manholes/Handhole ground rod Ensure contractor installs a ground rod in each power manhole and handhole. Note: This does not negate the equipment ground required for fixtures or luminaires.
Construction Issues:
Bushings Afghan-local electricians generally do not provide bushings where wiring and/or conduit enters junction boxes and panelboards. This could result in damaged insulation, which could cause a fault. See PDF’s Guide To International (NEC) Code Mod 6 Slides 3,4 & 8; See UFGS Specification 26 20 00 Para 3.1.6.16.
Stranded Wire 4mm2 and 6mm2 conductors shall be solid, not stranded. Contractors have been using stranded conductors for all wiring. Stranded wire requires a crimp connector to terminate on a bus. See UFGS Specification 26 20 00 Paras 2.9.1 and 2.10. Also see NEC 110.14; 310.3
Electrical-Taped Splices Afghan-local electricians generally splice conductors by twisting the stranded wires and wrapping with electrical tape. Splices shall be made with proper products: e.g. wire nuts. See NEC 110.7 & 14(B), 2008 edition |
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Inspection Checklist with NEC, NFPA 70, code references |
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