Automatic & Manual Transfer Switch Installation
When we install a Briggs and Stratton standby generator, the generator is only one half of the system. The other major component is the transfer switch, the equipment responsible for making sure the building receives power from the correct source.
At Pinellas County Electric, The Panel Pros™, we install manual and automatic transfer systems for residential and commercial properties throughout Clearwater and Pinellas County. Our projects range from 100- and 200 amp residential manual transfer systems to 100 and 200 amp residential automatic transfer switches to large three-phase commercial automatic transfer systems up to 1,000 amps and beyond when the project requires it.
We primarily install Briggs & Stratton standby generators. For larger commercial three-phase applications, particularly once we’re above the smaller transfer equipment range, ASCO Power Technologies is one of the transfer switch manufacturers we trust.
One thing I explain to customers is that a transfer switch isn’t simply a switch between two electrical sources. It is a critical part of the standby power system because it must prevent the utility and generator sources from being unintentionally connected together while safely transferring the building load from one source to the other.
Key Takeaways
A manual transfer switch requires a person to physically initiate the transfer from utility power to generator power. An automatic transfer switch, or ATS, monitors utility power and can signal a permanently installed standby generator to start and transfer the designated loads automatically when utility power fails.
For residential applications, we commonly work with 100 to 200 amp manual transfer arrangements and 100 to 200 amp automatic transfer switches. Briggs & Stratton currently offers residential automatic transfer equipment in 100, 150, 200 amp, and larger configurations.
Commercial systems can become substantially larger. Pinellas County Electric installs three-phase automatic transfer systems for commercial buildings, including systems approaching 1,000 amps where required by the facility. For many of our larger three-phase applications, we use ASCO transfer equipment with our Briggs & Stratton generator systems.
The correct transfer switch depends on much more than amperage. We evaluate voltage, phase, load, available fault current, short-circuit withstand and closing ratings, number of poles, neutral configuration, service entrance requirements, generator capacity, motor loads, and whether the system is optional standby, legally required standby, or emergency power.
Simple, Reliable Backup Power
A manual transfer system can be an excellent option for homeowners who want dependable emergency power but don’t necessarily need their home to automatically switch to generator power when the utility fails. It provides a more affordable way to operate important loads during an outage while keeping the generator system properly separated from the utility. But wait, there are some things you need to know.
With a manual system, someone needs to be present to safely position and start the portable generator, connect it to the approved generator 50amp inlet, and manually transfer the electrical system from utility power to generator power. When utility power returns, the process is reversed, and the generator can be disconnected and stored.
One of the biggest things we look at before installing a manual transfer system is what the homeowner actually expects the portable generator to operate. Refrigerators, AC units, freezers, lighting, televisions, internet equipment, receptacles, and other smaller loads are usually fairly straightforward. Air conditioning is a different conversation because the compressor can require a substantial amount of power for a fraction of a second when it starts. In some installations, an appropriately selected A/C soft-start device may be needed to reduce the compressor’s starting demand enough for the portable generator to successfully start the air conditioner. The generator still needs sufficient running and starting capacity for the equipment being supplied.
Manual Transfer Systems vs. Standby Generators
The important part of any manual generator installation is having a properly designed transfer method that provides a controlled means of selecting between utility power and generator power while preventing the two sources from being unintentionally connected together, using the appropriate tools for the installation. That’s completely different from someone attempting to backfeed their electrical panel through a dryer receptacle, range outlet, or another improvised connection. We want the generator connected through equipment specifically designed for the purpose.
For most residential portable-generator installations, 30 amp and 50 amp, 120/240 volt connections are the most common options. A 30 amp connection can provide up to approximately 7,200 watts at 240 volts, while a 50 amp connection can provide up to 12,000 watts at 240 volts, provided the generator itself is actually capable of producing that output. Installing a 50 amp inlet does not make a smaller generator capable of producing 50 amps. The generator’s rated output ultimately determines how much power is available to the home.
There are portable generators capable of producing more than 12,000 watts, but manufacturers may distribute that additional capacity across multiple receptacles rather than providing a single 100 or 200 amp residential plug-and-cord connection. This is why there comes a point where trying to make a portable generator operate an entire large home becomes less practical.
When a customer wants substantially more backup capacity, wants to operate larger loads without constantly deciding what can be turned on, or simply wants the system to work automatically whether they’re home or not, that’s when we generally recommend moving into a permanently installed Briggs & Stratton standby generator with a 100 or 200 amp automatic transfer system.
That’s really how I explain the difference to our customers. A manual transfer system is an economical and dependable way to provide selected backup power when you’re willing to manage the generator yourself. An automatic standby system is designed to take care of the process for you.
Backup Power Without Someone Being There
An automatic transfer switch changes the entire experience. When utility power fails, the system detects the loss of normal power and signals the standby generator to start. Once the generator reaches acceptable operating conditions, the ATS transfers the designated building load from utility power to generator power.
When utility power returns and stabilizes, the ATS transfers the load back to the utility. The generator then completes its programmed cooldown sequence and returns to standby.
Briggs & Stratton describes this same basic sequence in its current standby-generator documentation. That means the property owner doesn’t need to be standing beside the electrical equipment when the outage occurs.
For a home, that means the air conditioning, refrigeration, lighting and selected household loads can return automatically.
For a commercial property, automatic operation can be considerably more important. Refrigeration, security, pumps, access control, communications, lighting, HVAC, computer systems and other important equipment may need power even when nobody is at the building.
Residential Automatic Transfer Switches, 100 to 200 Amps
For our residential standby generator installations, we primarily use Briggs & Stratton generators and compatible transfer equipment. Briggs currently offers residential ATS configurations including 100, 150, and 200 amp equipment, as well as larger split distribution solutions for certain applications.
This works extremely well with the residential generator systems we install. But a 200-amp electrical service doesn’t automatically mean every appliance in the house can run simultaneously on whatever generator is connected to it.
We still need to size the generator properly and determine whether load management is necessary. The transfer switch determines where the power comes from. The generator still has to be capable of producing the power we’re asking it to supply.
Commercial Automatic Transfer Switches Up to 1,000 Amps
Commercial transfer systems are where these projects become considerably more involved. Pinellas County Electric works with commercial automatic transfer equipment up to 1,000 amps, including large three-phase systems.
Once we’re getting into larger three-phase commercial applications, ASCO Power Technologies becomes an important part of our equipment strategy.
In fact, Briggs & Stratton itself has previously partnered with ASCO for transfer equipment supporting its light commercial standby generator lineup, describing ASCO as an established leader in power transfer and citing its reputation for transfer equipment designed to manage large electrical loads.
That relationship makes sense to me. We’re comfortable pairing Briggs & Stratton generation with ASCO transfer equipment where the project design calls for it.
Why We Like ASCO Transfer Switches
When I’m putting a transfer switch on a large commercial building, I’m not looking for the cheapest switch I can find.
I’m looking at what that switch may be expected to do years from now during a hurricane when utility power disappears.
ASCO has a long-established product line dedicated specifically to power transfer equipment, including the Series 300 and Series 7000 families for commercial and critical power applications. One of the things I particularly like about serious commercial transfer equipment is the attention given to withstand and closing ratings, switching capability, controls, serviceability and UL 1008 testing.
UL 1008 is particularly important for transfer equipment. ASCO explains that UL 1008 testing evaluates transfer equipment under demanding overload, endurance and short circuit conditions, including its ability to withstand and close on fault current under its rated conditions.
When we’re transferring hundreds of amps of three-phase power between two sources, those details matter to me.
Manual Doesn't Mean Improvised
There’s another distinction I want customers to understand. Just because a transfer switch is manually operated doesn’t mean it should be an improvised switching arrangement.
ASCO specifically discusses the differences between transfer switches evaluated under UL 1008 and ordinary enclosed switches evaluated under UL 98. UL 1008 transfer equipment undergoes substantially different testing associated with transferring loads between power sources. That is why we select transfer equipment according to the application.
A transfer switch is doing something very important: It is deciding which electrical source is connected to the building. I want equipment designed and listed for that purpose.
NEC Article 702, Optional Standby Systems
Many of the residential and commercial generator systems we install fall under NEC Article 702, Optional Standby Systems. These are systems installed for reasons such as business continuity, convenience, refrigeration, HVAC, property protection, or maintaining operations during an outage when the loads aren’t otherwise classified as emergency or legally required standby loads.
Article 702 addresses the standby system, including its transfer equipment and capacity requirements. A transfer system must prevent inadvertent interconnection of the normal and alternate sources unless the equipment is specifically designed for permitted parallel operation, utilizing appropriate tools to ensure safety and efficiency.
That’s the fundamental safety principle behind the entire transfer system. Utility and generator power can’t simply be tied together.
NEC Articles 700 & 701
Not every commercial generator installation is optional standby. NEC Article 700 covers Emergency Systems, while NEC Article 701 covers Legally Required Standby Systems.
Those classifications can significantly change the requirements for the transfer equipment and overall standby system.
For emergency systems, NEC 700.5 requires transfer equipment to be automatic, listed, and marked for emergency use. It also requires the equipment to prevent inadvertent interconnection of the normal and emergency sources.
That’s an excellent example of why a manual transfer switch isn’t automatically acceptable everywhere simply because it can transfer power. We first determine what classification of standby system we’re actually designing.
NEC Article 445, Generators
NEC Article 445 covers generators themselves and works alongside the applicable standby-system article.
The generator has requirements involving matters such as disconnecting means, overcurrent protection, conductors, equipment ratings and shutdown provisions.
When we’re installing a Briggs & Stratton standby generator, we’re evaluating the generator and transfer equipment as a complete system rather than treating them as unrelated pieces of equipment.
NEC Article 250, Grounding & Bonding
Transfer switches also play a major role in determining how the generator system is grounded and bonded.
One question we need to answer is whether the generator will operate as a separately derived system. That can depend on whether the transfer equipment switches the neutral conductor.
This is why the difference between a three-pole and four-pole transfer switch can be much more important than somebody realizes. The neutral arrangement affects grounding and bonding, which brings NEC Article 250 directly into the design.
We don’t simply install another ground rod beside the generator and consider the grounding system finished. The generator, transfer switch, service equipment, grounded conductor, and equipment grounding system all need to work together correctly.
NEC 110.9, 110.10 & Available Fault Current
On larger commercial transfer switches, available fault current becomes another major consideration. NEC 110.9 addresses interrupting ratings, while NEC 110.10 addresses circuit impedance, short circuit current ratings and the characteristics necessary for the electrical system to safely clear faults.
This connects directly to the withstand and closing rating of the transfer switch. If the utility transformer is located directly beside the electrical service, we may have substantial available fault current at the transfer equipment.
That’s another reason we use commercial transfer equipment designed for the electrical conditions at the building instead of selecting an ATS solely because its amp rating matches the service.
NFPA 110 & Standby Power Systems
Depending on the building and classification of the standby power system, NFPA 110, Standard for Emergency and Standby Power Systems, can also become part of the project.
NFPA 110 addresses emergency and standby power systems where reliability, performance, installation, and maintenance become particularly important. This can affect the generator, transfer equipment, controls, testing and overall system design.
Not every generator installation falls into the same NFPA 110 classification, which is why we determine the requirements of the facility before ordering equipment.
NFPA 37 & Generator Installation
Transfer switches also play a major role in determining how the generator system is grounded and bonded. One question we need to answer is whether the generator will operate as a separately derived system.
That can depend on whether the transfer equipment switches the neutral conductor. This is why the difference between a three-pole and four-pole transfer switch can be much more important than somebody realizes.
The neutral arrangement affects grounding and bonding, which brings NEC Article 250 directly into the design. We don’t simply install another ground rod beside the generator and consider the grounding system finished.
The generator, transfer switch, service equipment, grounded conductor, and equipment grounding system all need to work together correctly.
NEC 110.9, 110.10 & Available Fault Current
On larger commercial transfer switches, available fault current becomes another major consideration.
NEC 110.9 addresses interrupting ratings, while NEC 110.10 addresses circuit impedance, short circuit current ratings and the characteristics necessary for the electrical system to safely clear faults.
This connects directly to the withstand and closing rating of the transfer switch.
If the utility transformer is located directly beside the electrical service, we may have substantial available fault current at the transfer equipment.
That’s another reason we use commercial transfer equipment designed for the electrical conditions at the building instead of selecting an ATS solely because its amp rating matches the service.
NFPA 110 & Standby Power Systems
Depending on the building and classification of the standby power system, NFPA 110, Standard for Emergency and Standby Power Systems, can also become part of the project.
NFPA 110 addresses emergency and standby power systems where reliability, performance, installation, and maintenance become particularly important.
This can affect the generator, transfer equipment, controls, testing and overall system design.
Not every generator installation falls into the same NFPA 110 classification, which is why we determine the requirements of the facility before ordering equipment.
NFPA 37 & Generator Installation
NFPA 37 can also apply to the installation of stationary combustion engines such as generator engines.
This brings the physical generator installation into the conversation, including fire safety and installation considerations.
- The electrical plans may show where we'd like the generator to go.
- That doesn't automatically mean we can physically put it there.
And on commercial generator projects, that’s where the crane, concrete pad and site logistics become a major part of our planning.
Setting a Commercial Generator Usually Requires a Crane
A 125 kW commercial generator is not something four electricians pick up and carry around the side of a building.
These are substantial pieces of equipment. For many of our larger Briggs & Stratton commercial generator installations, we coordinate a crane to set the generator onto its prepared concrete equipment pad.
Before I approve a generator location, I’m already thinking about how we’re going to physically get it there.
- Can the crane get onto the property?
- Is there enough room for the truck?
- Can the outriggers be deployed safely?
- How far does the boom need to reach?
- What's between the crane and generator pad?
That’s why generator placement isn’t simply an electrical decision.
Power Lines Can Change the Entire Generator Plan
Overhead electrical lines are one of the biggest obstacles during a crane pick.
A crane company isn’t simply going to boom over energized power lines because that’s the shortest route to the generator pad. Crane operations around energized lines are subject to strict clearance and safety requirements.
So before we finalize the pad location, I want to understand the crane path. A crane may be capable of lifting a generator over portions of a building when the lift plan, crane capacity, reach, and site conditions allow it.
But overhead utility lines can eliminate what otherwise looks like the easiest route. That’s something we need to discover before the generator and crane arrive.
The Concrete Generator Pad Needs to Be Engineered Correctly
Before the crane sets the generator, the concrete pad needs to be ready. For our larger commercial installations, this normally means coordinating with the general contractor and, where required, the engineer for the equipment foundation.
The pad isn’t something I want somebody pouring from a rough measurement taken off a generator brochure.
The project may require drawings showing the generator footprint, concrete dimensions, reinforcement, equipment weight, anchor locations, elevation, structural requirements, and the specific tools necessary for each stage. Depending on the project and jurisdiction, structural documentation and concrete strength information or testing may also be required.
The exact foundation design needs to follow the generator manufacturer’s requirements, engineered plans, and local permitting requirements.
The Concrete Has to Cure Before We Set Thousands of Pounds on It
This also affects scheduling. Pouring the pad doesn’t mean we’re setting the generator the next morning.
Concrete needs time to develop the required strength before we’re comfortable placing thousands of pounds of generator equipment onto it and anchoring that equipment.
The required strength and timing should follow the approved structural design and project specifications. This is why commercial generator projects need to be scheduled in stages.
Permitting first. Site work. Pad construction. Concrete curing. Generator delivery. Crane set. Electrical work. Gas work. Startup. Testing. Inspection. Trying to compress all of that into a couple of days is how expensive mistakes happen.
Anchoring the Generator to the Pad
Once the generator is positioned, it also needs to be properly secured.
On the larger commercial generator installations we perform, we’re commonly dealing with a substantial anchoring system, often involving 5/8 inch or larger anchors, depending on the manufacturer’s requirements and the engineered foundation design. The anchor system is part of the engineered installation, not something we decide after the generator is already sitting on the concrete.
Commercial Generator Permitting Takes Planning
One of the biggest things I want customers to understand is that a commercial generator project isn’t normally an instant permit.
On our projects, I tell customers to plan for the permitting and review process to potentially take several weeks, and in some cases around six weeks or longer, depending on the municipality, completeness of the drawings, engineering, review comments, and workload.
Pinellas County itself explains that commercial permits can involve review by several different disciplines and may require architectural, structural, mechanical, electrical, plumbing and life-safety documentation. Its published initial commercial plan-review target is approximately 10 to 20 working days, but that is the initial review and does not guarantee final permit issuance within that period. Corrections and resubmittals can extend the overall process.
That’s why I would rather tell a customer early: Don’t order the crane for next Friday because we submitted the permit yesterday.
The Electrical Contractor Often Becomes the Lead Contractor
Commercial generator projects normally involve several trades. There is the electrical contractor, the gas contractor, and often a general contractor responsible for the concrete foundation and associated construction work.
On many of our generator projects, Pinellas County Electric carries the largest portion of the project scope and cost because we’re supplying and installing the generator, transfer equipment, and major electrical infrastructure. In those situations, we commonly function as the prime or lead contractor for the project, while the appropriately licensed gas contractor and general contractor participate under the permitting structure required by that jurisdiction.
Exactly how permits and associated contractors are structured can vary by building department, so we confirm the process before submitting.
Pinellas County specifically identifies generator work as an electrical permit type while also maintaining separate permit categories for concrete slabs or foundations and new or extended gas systems. That gives you an idea of why these projects can involve several different reviews.
Every Municipality Is Different
This is something we’ve learned through experience working throughout Pinellas County.
Clearwater may want something presented one way. St. Petersburg may have a different process. Largo may require additional documentation or review steps. Other municipalities may handle generator projects differently again.
From our experience, Largo, FL & Pinellas Park, FL can be one of the more demanding jurisdictions for complex generator and electrical permit packages, so when we’re working there, we plan accordingly. That’s our experience dealing with the permitting process, rather than a statement that Largo officially has longer review times than every other city.
The important thing for the customer is that we know going into the project that commercial generator permitting requires documentation.
We would much rather give the municipality a complete package the first time than lose weeks going back and forth because something was missing.
NEC & NFPA References for Transfer Switch & Generator Installations
Depending on the project and locally adopted code edition, we may evaluate NEC 110.3(B) for listed equipment and manufacturer’s instructions, NEC 110.9 for interrupting ratings, NEC 110.10 for short circuit current and equipment ratings, NEC 110.26 for electrical working space, Article 220 for load calculations, Article 230 where the transfer equipment interacts with the service, Article 240 for overcurrent protection, Article 250 for grounding and bonding, Article 445 for generators, Article 700 and 700.5 for emergency systems and transfer equipment, Article 701 for legally required standby systems, Article 702 for optional standby systems, and Article 708 where Critical Operations Power Systems are involved.
Depending on the facility, we may also need to consider NFPA 37 for stationary combustion engines, NFPA 110 for emergency and standby power systems, UL 1008 for transfer equipment, UL 2200 for stationary generator assemblies, Briggs & Stratton installation requirements, ASCO installation requirements, Florida Building Code requirements, fuel-gas requirements, engineered foundation requirements, and the requirements of the local authority having jurisdiction.
The point isn’t to overwhelm the customer with code numbers. The point is to show why a properly installed standby power system requires more than buying a generator and connecting a few wires.
Automatic & Manual Transfer Switch FAQs
What is the biggest difference between a manual and automatic transfer switch?
A manual transfer switch requires someone to initiate the transfer between the utility and generator sources. An automatic transfer switch monitors the normal source and can automatically start the standby generator and transfer the designated loads when utility power fails. Which system makes sense depends on the property, generator, and importance of maintaining power.
What size transfer switches does Pinellas County Electric install?
For residential applications, we commonly work with 100 to 200 amp manual transfer systems and 100 to 200 amp automatic transfer switches. For commercial properties, we install much larger three-phase automatic transfer systems, including applications up to 1,000 amps, depending on the electrical system and facility requirements.
Why does Pinellas County Electric use ASCO for larger commercial transfer switches?
ASCO specializes in power transfer equipment and offers commercial products designed around demanding transfer, fault-current, and reliability requirements. ASCO transfer switches are available with UL 1008 ratings and commercial configurations suitable for large electrical systems. Briggs & Stratton has also partnered with ASCO for transfer equipment used with portions of its commercial standby generator lineup.
Why does a commercial generator project take longer than a residential generator installation?
The generator itself may require engineering, a concrete foundation, crane access, electrical drawings, transfer equipment, gas design, structural review, permitting, and coordination between several licensed trades. Commercial permits may also pass through multiple plan-review disciplines before they are issued.
Should I call Pinellas County Electric before ordering the generator or transfer switch?
Absolutely. I want to look at the service voltage, amperage, phase, calculated load, available fault current, generator location, crane access, overhead power lines, gas supply, transfer switch location, concrete pad requirements, and permitting jurisdiction before thousands of dollars of equipment gets ordered.
Service Areas
- Pinellas County Electric installs automatic transfer switches
- manual generator transfer systems
- Briggs & Stratton standby generators
- ASCO commercial transfer switches
- three-phase generator systems
- commercial standby power systems throughout Clearwater
- Clearwater Beach
- St. Petersburg
- Largo
- Pinellas Park
- Safety Harbor
- Dunedin
- Palm Harbor
- Tarpon Springs
- Seminole
- Belleair
- Belleair Beach
- Indian Rocks Beach
- Indian Shores
- Madeira Beach
- Redington Beach
- Redington Shores
- North Redington Beach
- Treasure Island
- Gulfport
- Oldsmar
Surrounding communities throughout Pinellas County, Florida.
Planning a Generator or Transfer Switch Project?
Call us before you order the equipment.
At Pinellas County Electric, The Panel Pros™, we look at the entire project before deciding what belongs there.
For a residential project, that may mean a 100 or 200 amp manual transfer system or a Briggs & Stratton automatic standby generator system.
For a commercial property, it may mean a three-phase Briggs & Stratton generator, a large ASCO automatic transfer switch, engineered concrete foundation, crane placement, fuel system, load calculations, grounding and bonding, permitting, and coordination between several contractors.
I would rather identify those requirements before we give you the final scope than surprise you with change orders after construction begins.
Show the customer the entire picture upfront. Explain the options. Plan the project correctly. Then build the system the way we said we would.
Pinellas County Electric, The Panel Pros™ Automatic & Manual Transfer Switches Residential & Commercial Standby Power Systems Clearwater & Pinellas County, Florida 727-269-1982
