Okay, good morning! Let's break down these questions and provide some insights for your budget estimate on the temporary power for this demolition project.

Understanding the Scope



Complete Interior Demo

This is significant. It means everything is coming out, and the existing electrical system will likely be compromised quickly.

Budgetary Phase

Accuracy is still important, but you can make assumptions and include contingency based on possible equipment requirements.

Eight Floors, Three Buildings (Quadrants)

This helps size the overall power needs and plan distribution.

Working Top-Down

This simplifies some logistics, as debris and materials will be moving downwards.

Question Breakdown and Answers


Tools/Equipment Used by Other Trades for Demo/Gut

This is the crucial question. You need to have a good idea of this to determine the load for your temporary power. Here's a breakdown of likely equipment:

Demolition



Jackhammers/Breakers

These are power hogs! Consider the size (15-20 amp commonly) and quantity operating simultaneously per floor.

Saws

Reciprocating saws (Sawzalls), circular saws, concrete saws. 10-15 amps each.

Grinders

For cutting metal, concrete, etc. 7-10 amps.

Hammer Drills

For concrete and masonry demolition. 6-8 amps.

Air Compressors

If pneumatic tools are used. Depending on the tool being used, you might need a separate circuit for the compressor if it is a larger unit.

Debris Removal



Conveyor Belts

If used to move debris out of the building (unlikely for upper floors). 10-15 amps.

Small Electric Skid Steers/Wheelbarrows

If used to move debris on each floor. Probably battery-powered.

Dust Control/Air Quality



Negative Air Machines (HEPA Filters)

These are critical for safety. 5-10 amps each. The quantity depends on the area being demoed on each floor.

Fans

For ventilation.

Water Sprayers/Hoses

To suppress dust. No power needed here.

Lighting



High-Output LED Work Lights

They will be used in dark spaces during demo.

Determining Power Needs



Talk to the Demolition Contractor

Get their equipment list and expected usage. This is the most reliable way to get accurate information.

Estimate Based on Floor Area

Assume a certain number of tools per square foot/meter being demoed simultaneously.

Example

Let's say on each floor of each quadrant, they'll have: 2 Jackhammers @ 15 amps each = 30 amps 3 Saws @ 12 amps each = 36 amps 2 Grinders @ 8 amps each = 16 amps 2 Negative Air Machines @ 7 amps each = 14 amps Lighting = 5 amps (LED is efficient)

Total per Floor (Example)

30 + 36 + 16 + 14 + 5 =

101 amps per floor, per quadrant (This is just an example - get real numbers!). Add a Safety Factor

Increase this by 20-25% to account for simultaneous use, starting/surge currents, and unexpected needs.

Based on this example, you would need a temp service capable of 121 amps per floor, per quadrant.Therefore, you will need more than just light stringers and drop cords. You are almost guaranteed to need additional power.2. Temporary Riser and Panels

Based on the likely power needs identified above, this is the right approach. Stringers and drop cords alone will not be sufficient.

Temporary Riser

Yes, one riser per quadrant/building is the most logical and safest approach.

Panel Placement

Every other floor sounds reasonable to minimize voltage drop and distribution length. However, the best placement depends on the physical layout of the floors and where the demolition is actively happening. Consider: Accessibility of the panels. Minimizing long runs of cords. Safe routing of cords (away from foot traffic, potential damage).

Panel Size

Calculate the load per floor (as above) and size your panels accordingly. Don't forget to include spare breakers. 100 amp or 125 amp panels might be necessary, but that depends on the actual demand.

Wiring

Use appropriate gauge wire for the amperage and distances involved to minimize voltage drop. THHN/THWN in conduit is typical for this type of temporary power.3.

Using Existing Power

You are correct. Do not rely on the existing electrical system for temporary power during a complete demo. It will be unreliable, unsafe, and likely get damaged quickly.4.

Killing Existing Power

Absolutely. Once your temporary power is in place, de-energize the existing service at the main disconnect. Verify that everything is dead with a meter. Clearly label the disconnect as "Do Not Energize - Temporary Power in Use." Lockout/Tagout procedures are critical here. Coordinate with the demolition contractor to ensure everyone is aware of the switchover.

Additional Insights and Recommendations



Permitting and Inspections

Temporary power installations always require permits and inspections. Factor this into your budget and schedule.

Grounding

Ensure proper grounding of the temporary power system. This is critical for safety.

GFCI Protection

Use GFCI protection on all temporary circuits, especially those serving wet locations or power tools.

Weather Protection

If any temporary equipment is outdoors, ensure it is weather-rated (NEMA 3R or better).

Cord Management

Implement a cord management system to prevent tripping hazards. Use cord protectors where necessary.

Regular Inspections

Inspect the temporary power system regularly for damage, loose connections, and overloaded circuits.

Emergency Shut-Off

Consider adding a main disconnect switch that would kill the entire temporary power system in case of an emergency.

Security

Secure the temporary panels to prevent tampering or theft.

Lighting

Don't underestimate the need for good temporary lighting. Well-lit work areas are safer and more productive. LED is the way to go for efficiency.

Communication

Maintain open communication with the demolition contractor throughout the project to address any changing power needs.

Generator? Determine if the client would be open to use of a generator. With the right size generator you could provide power for 1-3 floors for demo.

In Summary:

You're on the right track with your thinking. The key is to get accurate* information about the power requirements of the demolition equipment. Talk to the demolition contractor, create a detailed load calculation, and then size your temporary power system accordingly.Good luck with the estimate! Remember to include a contingency in your budget to cover unforeseen costs or changes in scope. Flag for review