Quarterly News for California Building Departments

Issue #57, Jan - Mar 2018

After 12 years, the Willdan Letter news quarterly for California Building Departments, is retiring. Our employees are busy with work for Willdan's municipal clients for the foreseeable future. Never fear, the previously published newsletters and Dr. Chudy's exceptionally helpful, color-coded compilations Focus on the Codes for 2016 and 2013 will continue to be available, and we encourage you to bookmark and share them. Thank you to our hundreds of subscribers for your support and suggestions through the years.

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This is a TEST...

Can you identify what this device is and what code section relates to it? (Yellow arrow is pointing at it).

This photo was taken at a single family residence that had the FAU and Air Conditioning system replaced. The device is installed on the condensate drain line.

If you can identify the device and the related code section, please send me an email at: and tell me what you see. Good luck.

CSU Monterey Bay library
La Mirada Resource Center
CSU Stanislaus Science
Tracy City Hall

Pictured: A few buildings plan-checked or inspected by Willdan

Focus on the 2016 Codes

2016 California Codes Digest for Dwelling Inspections or Plan Review (Part 4 of a 4-part Series)

code books

Photo: special to Willdan

By Dan Chudy, Ph.D., CBO, LEED AP, CASp
Principal Project Manager – Willdan Engineering

architectural house drawing

A more logical way (at least for me) to organize and consolidate the most common residential code requirements is by segregating them according to the room in the house to which they apply.   With that in mind, I have compiled such a list in alphabetical order by room, and in 2016, the Willdan Letter published the list based on the 2013 California Codes (compiled here).

We have updated the list to correlate with the new 2016 California Codes (Running compilation here).

NOTE: Although many of thecode citations herein are carry-overs from the 2013 California Codes, some are new or substantially revised. Those code citations which are either new or substantially revised are highlighted in GREEN. Those code citations that were in the 2013 California Codes, but are not found in the 2016 California codes are highlighted in BLUE. Key words are highlighted in YELLOW in order to assist the user in quickly finding particular items of interest.

Please understand that this effort is a work in progress and I make no claim that the list is all inclusive nor that it is without error. If any errors or omissions are found, please email me at so that the list can be improved.

PART 4: ‘R’ (ROOF) thru ‘U’ (Utility room) in this Willdan Letter edition

Click the + next to each title to view its description, or click the "Show All" button.


CRC R303.5.1 – Air intake minimum 10’ from mechanical or plumbing vents, chimneys, parking lots, loading docks, alleys, or streets or air intake to be at least 3’ below vent outlet. (Exhaust vents from bathrooms and kitchens are exempt.)

CRC R308.6.8 - Skylights installed in a roof with a pitch flatter than 3:12 (25-percent slope) shall be mounted on a curb extending at least 4” above the plane of the roof unless otherwise specified in the manufacturer’s installation instruction. 

CRC R801.3 – Roof drainage to discharge at least 5’ from foundation in areas with expansive or collapsible soils.

CRC R802.3 – Roof hips and valley rafters less than 3:12 shall be designed as beams.

CRC R802.3.1 - Minimum size rafter tie is 2X4.

CRC R802.3.1 – Minimum size collar tie is 1X4 at 4’ oc.  Collar ties or ridge straps (1.25”X20 gage) required.

CRC R802.5.1 – Purlins to be same size as rafter or larger.  Supported by 2X4 braces to bearing walls, not more than 4’ oc and unbraced length of brace is 8’ maximum and not less than 45 degrees from horizontal.

CRC R 802.7.1 – Notching roof structural members: Notching limited to 1/6 the depth of the member, not longer than 1/3 the depth of the member, not in the middle 1/3 of the member, at ends not more than 1/4 the depth of the member.  If 4” or greater in thickness, then no notching on tension side (bottom) except at ends.

CRC R 802.7.1 – Drilling structural roof members: Drilled holes limited to 1/3 the depth of the member, not closer than 2” from top or bottom of member or to any other hole or notch in the member.

CRC R802.7.1.1 – Notching cantilevered portion of rafter allowed if there is at least 3.5” remaining and the cantilever is not more than 24”.

CRC R802.7.1.2 – Taper cuts at the ends of ceiling joists shall not exceed 1/4  the depth of the joist.

CRC R802.8.1 – Rafters and ceiling joists larger than 2X12 to be blocked or wood strip nailed across joists/rafters at 8’ oc or less.

CRC R806.1 & R806.2 – Attics and enclosed rafter space (formed when ceiling is applied directly to bottom of rafter) must have cross-ventilation.  Openings to be covered with corrosion resistant screen (1/16” – 1/4” openings) at a rate of 1/150 or 1/300 if 40 – 50% of vents are in the upper 1/3 of the attic (not more than 3’ below the ridge) with the remainder at the eave or cornice.

CRC R806.3 – Insulation shall not block the eave or cornice vents.  1” minimum clearance between insulation and vent opening and between roof sheathing and insulation.

CRC R807.1 – Attic access required if combustible construction AND attic space is more than 30” tall (from bottom of rafter to top of ceiling joist) AND more than 30 square feet in area.

CRC R807.1 – Attic access to be 22”X30” minimum and located in a hallway or other readily accessible location.  Head clearance at opening to be 30” min at some point above the access (measured from the BOTTOM of the ceiling joist). 

CRC R1003.9 – Chimneys (metal, masonry, and factory built) shall terminate at least 2’ above any portion of the building within 10’ but not less than 3’ above the highest point where it passes thru the roof. (See also CMC802.5.4)

CRC R1003.20 – Chimneys require crickets where more than 30” wide at the intersection of the roof sloping into the chimney.

CMC 502.1 – Exhaust vents terminations outdoors shall be covered by screens with not less than ¼” openings and not more than ½” openings. (Except Dryer vents)

150.1(c)2 – Radiant barrier at roof required IF prescriptive approach used and T-24 calcs specify Radiant Barrier at roof. Radiant barrier (foil side) requires air space to be effective, therefore if placed over existing sheathing there must be a 1-inch thick spacer between (per CEC Blueprint issue 112– November 2015)

150.1(c)2 – If radiant barriers are required on the roof by the T-24 calcs, the Gable ends of the attic must also be provided with a radiant barrier.

CRC Table R503.2.1.1(1) footnote b – Minimum length of plywood panel must span 3 or more rafters (i.e. “2 or more spans”).

CRC Table R503.2.1.1(1) footnote c –Minimum width of plywood panel is 24”.

CRC Table R602.3(1) – Item #30, Required nailing: 8d nails @ 6” o.c. on edges and 12” o.c. at intermediate supports (i.e. in the “field”).

CRC Table R602.3(2) – Staples for 1/2" plywood on roof to be 1.75” long, 7/16” crown, 4” o.c. edge, 8” o.c. field, OR 3” edge/6” field depending on thickness gage of staple.

CRC R803.2.1.1 – Plywood exposed on underside to outdoor environment to be Exposure 1 grade.

CRC R803.2.3 – Plywood joints to be staggered

CEC 150.1(c)2 – Radiant barrier at roof required IF prescriptive approach used and T-24 calcs specify Radiant Barrier at roof.  Radiant barrier (foil side) requires air space to be effective, therefore if placed over existing sheathing there must be a 1-inch thick spacer between (per CEC Blueprint issue 112– November 2015).

CEC 150.1(c)2 – If radiant barriers are required on the roof by the T-24 calcs, the Gable ends of the attic must also be provided with a radiant barrier.

CMC Table 802.6.2 – Vent termination height above roof is 12” minimum when the roof slope is 6/12 or less and the vent is more than 8’ from a vertical wall and the vent is not more than 12” in diameter.  Where the vent is less than 8’ from a vertical wall OR more than 12” in diameter, the vent termination is to be at least 2’ above any portion of the building within 10’ horizontally and not less than 2’ above the roof where they pass through.

CRC R902.1.1 – Very High Fire severity zones require Class A (including >50% replacement roofs)

CRC R903.2.1 – Flashings required at roof/wall intersections (No. 26 gage galv steel or equal)

CRC R903.2.2 – Chimney or similar roof penetration of 30” or more in width require a cricket or saddle on the ridge side.

CRC R903.2.3 – Parapet walls require a noncombustible and weatherproof cap

CRC R905.2.5 – Fastener length for asphalt shingles = 3/4” into the roof sheathing or at least as thick as the sheathing material

CRC R905.2.8.5 – Drip edge required on asphalt shingles. Nailed at 12” o.c. maximum with minimum 2” overlap at adjacent segments.  Underlayment under drip edge at eave but over drip edge at gables

CRC R908.1 – Reroofs are NOT required to meet the minimum slope requirements of 1/4:12 as long as there is positive roof drainage

CRC R908.3 – 2 roof coverings maximum, then remove all existing layers of roof coverings

CRC Table R905.1.1(2) – Underlayment to be attached using metal or plastic cap nails or cap staples ONLY IN REGIONS WITH WIND SPEEDS IN EXCESS OF 140 MPH

CRC Table R905.1.1(2) – Roofing materials and minimum slope:

Material Minimum Slope Double Underlayment
Asphalt Shingle 2:12 2:12 – 4:12
Clay and Concrete Tile 2-1/2: 12 2-1/2: 12 – 4/12
Metal Shingle Per Manufacturer’s Specifications Per Manufacturer’s Specifications
Roll Roofing
Wood Shingle
Wood Shake
Metal Roof Panel
(lapped w/o sealant)
Metal Roof Panel
(lapped with sealant)
Metal Roof Panel
(standing seam)
Modified Bitumen
Thermoset Single-ply
Thermoplastic Single-ply
Sprayed Polyurethane Foam
Liquid-applied roofing
Hot Mop (Built-up)
Built-up Coal-tar

CRC R905.3.7 – Tile roofing on roof pitch of less than 5:12 do not need tiles to be nailed to sheathing IF battens are used.  If equal to 5:12 and greater pitch, then 1 nail per tile is required.

110.10 Solar Ready Mandatory Measure – subdivisions of 10 homes or more. 250 square feet solar roof area, specific orientation required if roof slope >2:12 (110 – 270 degrees from North), No obstructions that would shade the solar zone, connection pathway for electrical or plumbing, electrical service 200 Amp minimum busbar and space for future solar breaker (with label).


CRC R202 – Flight of stairs is from one landing to the next landing.

CRC R 202 – By extension of the definitions, a stairway has 2 or more treads (3 or more risers).

CRC R302.11 #3 – Fireblocking required at wood stair stringers.

CRC R302.7 – ½” gypsum board required on walls and lid in accessible enclosed space under stairs.

CRC 303.7 – Landings and treads of stairway shall be illuminated (1 foot-candle min) with a wall switch at each floor level when there are 6 or more risers.

CRC R303.8 – Exterior stairways to be provided with illumination at the top landing; unless to a basement, then the light is to be at the bottom of the stairway.

CRC R308.4.7 – Glazing adjacent to the bottom stair landing is considered to be a hazardous location when: glazing is less than 36” above the landing, AND within a 60” horizontal arc of 180 degrees from the bottom tread.

CRC R311.3 – Landings depth to be not less than the width of the door served.

CRC R311.3.2 Exception – No landing required on exterior side of door where stairway is 2 or fewer risers ( 1 tread) and door does not swing over stairway.

CRC R311.3.3 – Storm and screen doors may swing over exterior stairs and landings.

CRC R311.4 – Egress stairway or ramp required in levels not at grade.

CRC R311.4 – Maximum travel distance to a stairway or ramp on floors above the second floor is 50’.

CRC R311.7.1 – Minimum stairway width of 36” required above the handrail to the required head clearance.

CRC R311.7.1 – Minimum stairway width at and below handrail is 31.5” if handrail on one side, 27” if handrails on both sides.

CRC R311.7.1 – Maximum handrail projection 4.5” for each side.

CRC R311.7.2 – Minimum headroom 6’-8” from nosing (except at point where head clearance passes through floor opening – reduced head clearance may project horizontally 4.75” from perpendicular line from nosing of step).

CRC R312.7.3Maximum vertical rise 12’-3” between floor levels or landings.

CRC R311.7.5.1 – Maximum riser 7.75”, max variance 3/8”, max slope on riser 30 degrees from vertical.

CRC R311.7.5.1Maximum open riser: 4” sphere cannot pass thru (Except risers 30” or less above grade)

CRC R311.7.5.2 – Minimum tread 10”, max 3/8 variance.

CRC R311.7.5.3 – Nosing required on treads less than 11” when closed risers, nosing to be between ¾” min to 1.25” max, nosing to be radius max 9/16”, beveling of nosing not to exceed ½”, max variance 3/8”.

CRC R311.7.6 – Stair landings minimum 36” in depth (can be shape of a ¼ circle w/min 36” radius).

CRC R311.7.6 Exception – Landing not required at top of interior flight of stairs provided door does not swing over stairs (including enclosed garages).

CRC R311.7.7 – 2% maximum slope on treads and landings.

CRC R311.7.9 – Stairs shall be provided with illumination (see R303.7, R 303.8).

CRC R311.7.10.1 – Spiral stairs shall have min clear width of 26” at and below handrails, 7.5” min tread depth at 12”, all treads identical, rise 9.5” max, 6’-6” min head room.

CRC R311.7.8 – Handrails required on at least 1 side if 4 or more risers.

CRC R311.7.8.1 – Handrail height 34” – 38” measured from nosing to top of rail (except at first step and also at the transition from handrail to guardrail and transition from flight to flight and transition at winders).

CRC R311.7.8.2 – Handrails to be continuous between flights and returned to wall or newel post and be 1.5” from wall.

CRC R311.7.8.2 – Continuous handrail can be interrupted by newel post at turns and at lowest tread.

CRC R311.7.8.3 – Handgrip size limitations:

Type I Type II
Circular Not circular Perimeter Greater than 6.25”
Cross-section Cross-section Perimeter Finger recess on both sides ¾” max from top, min 5/16” deep. Finger grip to be located 7/8” max below widest point, etc.
1.25”- 2” 2.25” 4” - 6.25”

CRC R312.1.1 – Guardrails required at walking surfaces more than 30” above grade or floor and within 36” horizontally of said drop.

CRC R312.1.1 – Insect screening NOT considered a guard.

CRC R312.1.2 – 42” minimum height above walking surface.

CRC R312.1.2 Exceptions – Guard height at stairs is minimum 34”.

CRC R312.1.3 – Openings in guards to be less than 4” (4” sphere shall NOT pass thru) Exceptions: triangular opening at tread/riser intersection = 6”, and along open side of stairs = 4-3/8”.

CRC R312.2.1 – Windows more than 6’ above surface below shall have minimum sill height of 24” OR the opening below 24” cannot allow a 4” sphere to pass (Exception: window fall prevention protection devices).

CBC 1607.8.1 - (200 lb point load) Connection details of guardrail and/or handrail on open side of balconies, decks, landings, and stairs to be adequate to support 50 pounds per lineal foot at a right angle to the top rail, or a concentrated load of 200 lbs, whichever is greater.

CRC Section R312.1.3 - (When cables are used) Open guards shall have balusters or ornamental patterns such that a 4-inch diameter sphere cannot pass through any opening.  Experience and some code interpretation suggests the when using cables the spacing should be 2-1/2” on center with vertical supports at 4’-0” on center due to the deflection of the cables. 

CBC 1607.8.1 - (Support Post at 4’ oc)  4x post shall be spaced at 4’ o.c. (which will result in a 200 lb concentrated load – 50#/ft X 4’ = 200# ) or else the post shall be designed and calculations shall be provided for a 50 lb per linear foot loading.  With an 8’ o.c. spacing of the 4x post, the result is a 400 lb concentrated load.

CEC 210.70(A)2(c) – Stairways with 6 or more risers require light switches at each floor level (and another at the landing level when the landing is an entryway). (Exception for automatic, central or remote-controlled lights).

CEC 240.24(F) – Breakers shall not be located over steps of a stairway.

CRC R311.8.1 – Maximum slope 1:12 or 1:8 where technically infeasible and/or not a required exit.

CRC R311.8.2 & R311.3 – Ramp landings 3’ X 3’ at top and bottom and doors at ramp and change of direction.

CRC R311.8.3 – Handrails required only when slope exceeds 1:12 and only on one side.

CRC R311.8.3.1 – Handrail 34”-38” in height.


CRC R105.2 #1 – If single story and no more than 120 square feet in floor area, then exempt from permit.

CRC R202 If incidental to the dwelling on the same lot, then may be unlimited area.

CRC R302.1 – If exempt from permit, then not required to comply with wall ratings nor overhang limits.


SCAQMD Rule 445 – Applicable to portions of Southern California. Wood burning fireplaces NOT permitted in new construction (except if above 3,000 in elevation or no infrastructure for natural gas service within 150’ of property). Rule applies to all permanently installed indoor and outdoor wood burning fireplaces or fire pits.

CRC R308.4.5 – Glazing within 60” horizontally of swimming pool or spa water’s edge AND less than 60” above the walking surface required to be safety glass (i.e. tempered).  Applies to all panes of a multi-pane window.

CPC 1210.1.1 – Gas pipe burial depth is 12” minimum for steel (18” for PE plastic pipe per IAPMO IS12-2006) unless located where damage from external sources is likely, whereas it is 18” minimum.  Where 12” cannot be provided, the gas pipe is to be installed in a conduit or shielded (such as a nominal 4” thick concrete slab extending 6” beyond the pipe).

CPC 1210.1.7.2 – Plastic gas piping requires a corrosion resistant tracer wire to be minimum #14 AWG and continuous, extending above the riser at one end.

CEC 680.8 – Vertical clearance above a swimming pool to service drop conductors is 22.5’

CEC 680.10 – Underground wiring not allowed within 5’ of pool edge unless part of pool electrical wiring OR if there is insufficient space to re-route, then must be in conduit (Rigid, Intermediate, Nonmetallic)

CEC 680.10 – Burial depth for underground conduit for pools/spas is 18” for non-metallic conduit OR 6” burial depth minimum IF 4” thick concrete cover with NO vehicle traffic and concrete extends 6” beyond the conduit.

CEC 680.12 – Disconnect to be within sight of equipment, readily accessible and NOT closer than 5’ to inside wall of pool unless separated by a wall which makes the reach path 5’ min.

CEC 680.21(C) – GFCI protection required for 120 or 240 volt / 15 and 20 amp circuits for pool motor equipment.

CEC 680.22(A)(1) – Dwelling to have at least (1) general purpose receptacle outlet between 6’ to 20’ from water’s edge (not more than 6’-6” above grade or floor).

CEC 680.22(A)(2) – Receptacle outlets for pump motors to be located at least 10’ from pool water’s edge (exception for 6’ if single receptacle of grounding type and GFCI protected).

CEC 680.22(A)(3) & 680.22(D) – Receptacle outlets OTHER THAN for the pumps shall be at least 6’ from water’s edge.

CEC 680.22(A)(4) – GFCI protection required for all 125 volt / 15 and 20 amp receptacles within 20’ of inside wall of pool.

CEC 680.22(B)(1) – Lights NOT allowed within 5’ horizontally of the inside wall of the pool unless 12’ above the high water line.

CEC 680.22(B)(4) – Lighting between 5’ to 10’ from inside wall of pool to be protected by GFCI, UNLESS installed 5’ or more above the high water line and rigidly secured a structure or enclosure.

CEC 680.22(C) – Switches to be at least 5’ from water’s edge unless separated by a solid fence or wall (with exceptions for special listings, etc).

CEC 680.26(B) - #8 AWG minimum for bonding pool steel

CEC 680.26(B)(2) – Equipotential Bonding.  3’ horizontal pool perimeter (deck) to be bonded at 4 points (minimum) uniformly spaced.  If no reinforcing steel in deck, then #8 wire 18” – 24” from inside pool wall (in concrete or 4” – 6” below grade)

CEC 680.26(B)(7) – All fixed metal parts to be bonded (includes: metal sheathed cables and raceways, metal pipe, metal awnings, metal fences, metal door and window frames, etc.)  EXCEPTION: if more than 5’ horizontally from water or more than 12’ vertically from water or diving platform, etc.

CEC 680.26(C) – Minimum 9 square inch conductive surface shall be in contact with pool water (could be part of pool equipment, metal fittings, etc.)

Health & Safety Code 115920 – 115929 Pool Fence and Gate regulations (Swimming Pool Safety Act):

-Applicable to pools and spas over 18” deep


(A)   Enclosure (i.e. fence) to be minimum 60” tall

-Any access gates to swing out (away from pool) and have self-latching and self-closing device placed at least 60” above ground (NOTE: Self-latching device height conflicts with 54” height in CBC 1010.1.9.2 Exception and CBC 3109.4.1.7)

-Vertical clearance from bottom of fence to ground is 2” maximum

- Gaps or voids in fence not to allow the passage of a 4” diameter sphere

- Outside surface of fence to be free of handholds or footholds that would allow a child under 5 years old to climb.

(B)   Exit alarms mounted no less than 54” above the floor on doors providing access to the pool.

(C)   Self-closing/self-latching devices with release mechanisms mounted no less than 54” above the floor on doors providing access to the pool.

(D)  Removable mesh fence with self-closing and self-latching gate with key lockable device.

(E)   Approved pool safety cover (ASTM1346)

(F)   Swimming pool alarm which goes off when a body enters the water.

Local ordinances and interpretations will supersede the State regulations.

Health & Safety Code 115928 – Anti-entrapment regulations:

  1. Special grates on drains less than 12” across
  2. At least (2) circulation drains per pump plumbed thru a “T” fitting with drains at least 3’ apart

110.4(a)1 – On-off switch required outside of heater and to be readily accessible.

110.4(b)1 – At least 36” of pipe shall be installed between the filter and the heater OR suction and return lines OR built-in connections for future solar heating equipment.

110.4(b)2 – Pool cover required if pool heater provided

110.4(b)3 – Programmable time switch or similar control required for water circulation motors

150(p)1(C) – Filtration pumps shall be sized (or programmed) so that the flow rate is NOT greater than the rate necessary to turn over the pool water volume in 6 hours or 36 gpm, whichever is greater.

150(p)1(D) – Pump motors used for filtration with a capacity of 1 horsepower or more shall be multi-speed.

150(p)2(A) – A length of straight pipe that is greater than or equal to 4 pipe diameters shall be installed before the pump.



CRC R317.1 – Wood to earth separation: to bottom of girders in crawl space = 12”, to bottom of joists in crawl space = 18”.

CRC R408.1 – Ventilation of underfloor spaces to be (1:150) 1 square foot for each 150 square feet of underfloor area (or 1:1500 if ground covered by a Class 1 vapor retarder material). One vent required to be within 3’ of each corner of the building.  Vent openings to be covered with a material that does not exceed ¼” maximum opening (i.e. heavy wire mesh screen).

CRC R408.4 – Access to underfloor space shall be either through the perimeter wall (16” X 24” minimum) or through the floor (18” X 24” minimum).

CRC R408.6 – Finish grade of under floor surface permitted to be located at the bottom of the footing.

CRC R408.6 – Finish grade of under floor surface permitted to be located at the bottom of the footing.

CEC 210.8(A)(4) – If receptacle outlets are installed in crawl spaces at or below grade, then GFCI protected receptacles are required.

CEC 210.70(A)(3) – At least (1) lighting outlet controlled by a switch required when there is storage or equipment requiring servicing in the underfloor space.

CPC 609.11 – All hot water pipes regardless of pipe size to be insulated with wall thickness of insulation equal to the pipe diameter up to 2”.

CPC 707.9Underfloor cleanouts must to within 5’ of underfloor access opening.

150.0(j)2) – R4 (1”) pipe insulation required on all HOT water pipes ¾” or larger to point of use and all HOT water pipes (regardless of size) to kitchen fixtures.  Also first 5’ of hot and cold water pipes at the water heater. Pipe insulation NOT required at framing penetrations.  Pipe in insulated wall cavity is acceptable ONLY if Quality Insulation Installation (QII) standards (HERS verification) are met.  Pipe in attic is exempt IF buried by at least 4” blown insulation.  Pipe Insulation to be 4” min from water heater flue.  Hot and cold water lines should be at least 2” apart (to allow 1” insulation on each pipe).  CPC 609.11 more restrictive – all hot water pipes regardless of pipe size to be insulated with wall thickness of insulation equal to the pipe diameter up to 2”.


Results from Last Test

In the last issue, we asked readers to email responses to this question: “What’s wrong with this picture?”

The first person to correctly identify the problem was James Moore, Electrical Plans Examiner and Electrical Inspector for the City of Vernon, California.  James correctly identified that the Inter System Bonding Terminal was missing, which was discussed in an article in Issue #52 of the Willdan Letter. 

The Intersystem Bonding Terminal is required by NEC 250.94.  Below are a few examples of Intersystem Bonding Terminals.

Thanks to ALL of those who emailed responses to the “TEST” question.

200-amp electrical panel

UFER Ground: Where did that name come from?

I was doing inspections on a tract of new homes the other day and the superintendent asked me where the name “UFER” came from.  I responded, “That’s a great question…. I don’t know.”  And being plagued with the “I gotta know” ailment (which affects many Building Inspectors), I set out to discover where the name came from.

First, let me describe what the National Electrical Code calls it.  NEC Article 250.52(A)(3)(1) describes the requirements for “Concrete-Encased Electrodes” of an electrical grounding system which has “One or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (1/2 in) in diameter, installed in one continuous 6.0 mm (20 ft) length …”.   To simplify, it is a 20-foot length of #4 rebar located in the footing.  Nowhere in the NEC (as far as I could find) is the word UFER used to describe a concrete-encased electrode.  So why do we call it a UFER ground?

Herbert Ufer was an engineer and a vice president for Underwriters Laboratories in the 1940s. At that time, the U.S. military was experiencing some grounding problems at their ordinance depots in Arizona. The military required low-resistance (5 ohms or less) grounding connections for its ammunition storage sites.

Mr. Ufer developed and tested a design that worked quite well in the dry climate conditions of Arizona. His design was to place a 20-foot long by ½” diameter steel reinforcing bar near the bottom of a 2-foot deep concrete footing. Tests over a 20-year period showed consistent resistance values of 2 to 5 ohms. His work eventually resulted in what we know today as the Concrete-encased electrode discussed in the NEC.


For a list of legislative actions which may have an impact on local building departments, visit the CALBO Legislative Watch page.