City of Houston (TX)

Codes

NEC Code Version

2023

Fire Code Version

2018 Building Code

Code List

2021 International Residential Code (IRC) Houston Amendments

2021 International Existing Building (IEBC) Houston Amendments

2021 Uniform Mechanical Code (UPC) Houston Amendments

2021 Uniform Plumbing Code (UPC) Houston Amendments

2023 National Electrical Code (NEC) Administrative Amendments

2021 International Energy Conversation Code (IECC) Houston Amendments

2021 International Swimming Pool and Spa Code (ISPSC) Houston Amendments

ASCE Code Specification

ASCE 7-22

SolarAPP+ & submittal

SolarAPP+ Status

Adopted

Any SolarAPP+ Restrictions

1

SolarAPP+ Restrictions

Storage Systems,Existing Systems,Trenching,Derate

How Many Plansets Required

1

Revision Required

1

Rough Inspection

None

New Planset Required For Module Swap

0

Stamps

Ee Stamp Required On SLD

Yes

Wet Stamps Required

Digital Structural,Digital Electrical

Structural Calculations Required

Yes

Ee Stamp Notes

Stamped Documents

• Pages (4-7a) require an EE digital stamp. Include the PE’s firm name and license number and date signed on stamped pages.

Stamp Location On Plans

Unspecified

Date On Stamps

Date Plans are Stamped

Fire setbacks

Fire Setback Enforced

1

Setback Notes

Structural & loads

Wind Speed

999

Wind Notes

Exposure C

https://ascehazardtool.org

Risk Categories:

Ground Mount Systems Risk Category: 1

Roof Mount Systems Risk Category: 2

Wind Load Requirements

• Reference Source: Use the ASCE website to generate the address-specific wind load report based on ASCE 7-22 code.
• Attachment: Print the ASCE 7-22 report and attach it to the plans as a reference.
• Compliance: Ensure any manufacturer letters comply with the address-specific wind load report.

Instructions for Designers

• Provide the printed ASCE 7-22 report and attach it to the plans.
• Correct any incorrect wind load references on the plans.

Structural Letter

• Update wind load references to ASCE 7-22 code instead of ASCE 7-16.
• Manually update the code in the structural calculations tools to reflect ASCE 7-22.

Snow Load

999

Max Attachment Spacing

96

Structural Notes

Stamped Documents

• Structural plan pages and Structural Engineer Letter shall be sealed, signed, and dated by the same Engineer.

Wind Load and Ballast System Compliance

• ASCE 7-22 compliance is required; references to ASCE 7-16 or the Existing Building Code are not accepted.

Do not include disclaimers on PE or EE stamps, such as:

• "Stamped for existing roof and attachment only."
• "Stamped for structural code compliance of roof framing only; not stamped for water leakage. Racking and attachments by others."

Structural PE Letter

• Must confirm that all modifications, attachments, and racking are approved for installation.
• Wind Speed: Use 142 MPH, Exposure C (142 Vult) on all calculations and reference IBC only for consistency.
• Provide a stamped PE letter with calculations for the selected installation method, as outlined in the Tesla Install letter.

Battery Projects

• The City of Houston requires structural calculations, battery mounting calculations, and a Tesla compliance letter, all stamped by a PE.
• The PE letter should confirm the structure can support additional load from the battery and wind resistance (142 Vult).

Reference Letters and Examples

• 9/14/21 (MW): Approved PE and manufacturer letters are attached in the files section.
• 9/1/21 (LN): Include structural calculations, Tesla Powerwall compliance letter, and load details as shown in the attached example PE calculations.

Minimum Ground On Roof

#6

Electrical

Electrical Load Calcs Required

Derates

Allowed POI

Load Side Taps,Line Side Taps,Meter Adapter,PV Breaker

Panel Schedule Required

Partial Home Backup

Service Ground Requirements

#6 BARE COPPER REQUIRED WHEN FREE AIR. TYPICALLY SOLAREDGE PROJECTS. REVISE #10AWG TO #6 BETWEEN JUNCTION BOX AND PANELS

Temperature Rating

75

De Rating Ampacity

0.96

Battery / ESS

Unique Battery Placards Needed

0

ESS Notes

Battery Installation Requirements

If the project requires relocation of loads to either a Main Panel Insert upstream of the Gateway/Backup Interface/System Controller or to a Backup Loads Panel, choose the option that allows the minimum number of loads needing to be relocated.

• Most likely you are going to be relocating a few large loads from the Existing MSP(aka the NEW Backup Loads Panel) to the NEW Main Panel Insert between the Utility Meter and the Gateway/Backup Interface/System Controller.
• This does not count as an MPU and the Main Panel Insert Cost is included in the cost of the battery. no need for any additional adders.

Site Plan

• Indicate if batteries will be stored inside or outside.
• Specify the type of room (e.g., non-habitable room, exterior, garage).

Spacing and Room Protection

• Maintain a minimum 3-foot separation between ESS units.
• If installed in an unfinished room, walls and ceiling must have 5/8" Type X gypsum board for protection.

Documentation

• Provide battery manufacturer’s engineering specs for installation.
• Include a PE letter from the installer confirming adherence to manufacturer specs or detailing any approved deviations.

Disconnect and Impact Protection

AC Disconnect

• Install a single AC Disconnect (VLLD) to isolate all generation sources (solar panels and battery).
• Alternatively, use multiple VLLDs, one for each generation source.

Location and Protection

• ESS should not be installed where it may be impacted by a vehicle.
• Place ESS at least 3 feet from any doors or windows inside a garage.
• Provide impact protection (e.g., guard posts) if the ESS is vulnerable to vehicle impact.

Guard Post Specifications

• Construct posts from steel, minimum 4 inches in diameter, and filled with concrete.
• Space posts no more than 4 feet apart, set 3 feet deep in a concrete footing (minimum 15 inches in diameter).
• Ensure posts extend 3 feet above ground and are positioned at least 3 feet from the ESS.

Equipment and Compliance (NEC and City Codes)

General Requirements (Powerwall and Gateway 2)

• Charge controllers for PV systems must be listed or field-labeled for PV use (Article 690.4, NEC 2023).
• Submit listings of approved equipment for review.
• Ensure spec sheets contain a stamped logo or a certificate from a recognized testing laboratory.

Labels and Markings (NEC 2023)

• Provide labels, code references, and specs compliant with NEC 2023 articles 690 and 705.
• Include a "Caution: Multiple Sources of Power" plaque per NEC 705.10, clearly showing each power source’s location.
• Attach the PW2 VoC 1741, PW2 1741SA, Backup Gateway 2 Voc, and PW2 UL9540A Test Result PDFs (available in the Files section).

Separate ESS Disconnect Required

Local Disconnect

ESS Elevation Detail Required

Yes

Plan set

Plan Set Requirements

ALL DESIGNERS MUST INCLUDE A COPY OF THE BELOW CHECKLIST WITHIN FILES SECTION OF LIGHTSPEED BEFORE COMPLETING DESIGN OR DESIGN REVISION.

City of Houston Checklist - YOU MUST DOWNLOAD A COPY TO EDIT - Google Sheets

ALL PLANS

• Spec sheets must contain a stamped logo, or a letter of certificate from an approved recognized testing laboratory.
• When a combiner box is to be used, provide a spec sheet

Add the following PDFs to ALL relevant projects (uploaded below)

1. REVISED UNIRAC Table Design Criteria (2 pages) to plans. Verify that the pitch matches the plan-set on the Appendix B Pressure Lookup Table.
2. City of Houston Current MFR Engineer Letter
3. 2017 SolarEdge Intertek document.

All Electrical sheets 4-7a shall include the Master Electrician’s signature, master's license number, and dated.

Cover Page

[ALL PLANS] Include Wind Speed/Snow Load/Exposure information on COVER PAGE

Site

ALL PLANS

• Add Fire setback dimensions to SITE PLAN
• Include and label all structures on property on SITE PLAN
• Include Wind Speed/Snow Load/Exposure information on SITE PLAN

Site Notes

All Jobs [NO ENCROACHMENT INTO EASEMENTS BY NEW SCOPE OF WORK (SOLAR PANELS, RACK/RAIL SYSTEM, EQUIPMENT // 142 VULT WIND SPEED]

Roof Plan

ALL PLANS

• SHOW DIMENSIONS ON EVERY FIRE SETBACK
• Include Wind Speed/Snow Load/Exposure information on ROOF PLAN

Roof Plan Notes

All Jobs [OVERCURRENT DEVICE AT PV SYSTEM DISCONNECT WILL BE LOCATED WITHIN 10' OF POINT OF CONNECTION TO THE SERVICE]

Attachment Detail

ALL PLANS

• Show Wind Speed/Snow Load/Exposure information on attachment detail
• Call out the specific attachment type to be used.
• IF USING ROCKIT ATTACHMENTS, INCLUDE THE "ROCKIT INSTALL GUIDE" WITHIN THE SPEC SHEETS ON ALL PROJECTS.

Attachment Detail Notes

Electrical Diagram

• All in one MPUs are not allowed
• ONLY MPUs require Surge Protection Device to be called out on ELD
• Branch does not allow derate to 175A Main Breaker
• If MSP is located on the interior, the Branch preferred POI is to add a Main Breaker Enclosure to the exterior of the home and and tap within the new enclosure. add a fused disconnect.
• All Taps must be within Main Breaker Enclosure.
• If we are combining with an existing pv system, please remove the existing systems ac disconnect and combine into a load center, then add a generation combined system pv disconnect to control the entire pv system. existing and new

Electrical Diagram Notes

All Jobs [Overcurrent device at PV system disconnect will be located within 10' of point of connection to service]

Label Page

ALL PLANS

• Provide all labels, code references, and specifications in compliance with 2023 N.E.C. article 690 N.E.C. Solar Photovoltaic Systems and article 705 Interconnected Electric Power Production System.
• Directory placard must have this verbiage - MULTIPLE SOURCES OF POWER LOCATED AS SHOWN. 
• See 2023 NEC Labels in file section - VERIFIED (3/29/24 by SGR)

Label Page Notes

All Jobs [MULTIPLE SOURCES OF POWER LOCATED AS SHOWN] 

Custom Placards Required

1

Placards Notes

Directory placard must have this verbiage - "MULTIPLE SOURCES OF POWER"

Non Standard Revision Requirements

All Designs must include 63A breaker for BUI and the BUI Spec Sheets. Please confirm these docs are on attached to your planset prior to uploading to files section. These Docs are within the AHJ Files Section.

Ground mount

Ground Mount Fencing Required

Mesh/Scrim