Resource Center
Transfer Switches FAQ
What is a generator transfer switch and why do I need one?
A transfer switch is the key to safe and convenient operation of portable generators for backup power. A manual transfer switch isolates those circuits using generator power during an outage, and eliminates the risk of back feeding the electrical utility which can cause injury to utility workers and property damage. Using a transfer switch for backup power also eliminates the need to run extension cords around the home or office to operate certain appliances.
How does a small transfer switch tie into my circuits?
A transfer switch transfers the load after the branch circuit breakers on the load side of the circuit. This allows the transfer switch to be installed without the labor and expense of moving the branch circuit breakers to another panel. It further allows the transfer to be made using a "light switch" type of toggle switch rather than switching a series of circuit breakers. Finally, a transfer switch can feed some of the circuits from the utility and others from the generator.
Why can't I just run extension cords from my generator to my appliances?
This can be done as long as no connection exists between the generator and the utility and the appliance and the utility, i.e. there is no chance of back feeding the utility. The advantage of a transfer switch over cords is that you can run devices that are not cord connected such as a furnace blower motor or wall and ceiling light fixtures. A transfer switch provides the convenience of utility power and eliminates the need to run extensions cords throughout the house. A transfer switch with meters can also help in managing power and balancing the generator load to make sure you maximize the available generator power
Are most small transfer switches automatic?
No. They are manual transfer switches designed for a homeowner or small business owner to use with a 5000-12,000 watt standby generator.
Are transfer switches pre-wired?
Yes . Most small transfer switches come completely pre-wired with a Red and Black wire for each circuit, plus a White neutral and Green ground wire. A 6-circuit unit has a total of 14 wires and a 10-circuit unit has a total of 22 wires, and so on.
I want to connect my well pump to my generator via a transfer switch. How many 2-pole circuits (commonly called 220, 230 or 240 volt) are provided on each transfer switch?
Generally the 6-circuit models can be configured for one (1) 2-pole circuit for use on one 240-volt circuit, and are provided with one (1) handle tie. The 8-circuit models can be configured for up to four (4) 2-pole breakers, and one (1) handle tie is provided. The 10-circuit models can usually be configured for up to five (5) 2-pole breakers, and two (2) handle ties are usually provided.
Additional handle ties can be purchased from the factory. See the replacement parts list.
If no 240 volt circuits are needed, the handle ties may be removed and discarded.
What type of connection is required to connect my generator to my transfer switch or Power Inlet Box?
A 4-wire, twist-lock connector is needed. We have all-rubber Power Cords with a male connector on one end and a female connector on the other end. 12 gauge wire is required for 5000 watt models, and 10 gauge wire is required for 7500 watt models.
Can I use a transfer switch on any 20 amp circuits in my house?
Yes. The switches and wires in each transfer switch are rated for 20 amps. However, in the generator mode, each circuit is limited to the amperage of the circuit breakers in the transfer switch. Some of these breakers are 15 amps and some are 20 amps. The circuits with 15 amp transfer switch breakers can be connected to either 15 or 20 amp circuits in the main panel. The circuits with the 20 amp transfer switch breakers must be connected to 20 amp circuits in the main panel. The 6 circuit models have a total of two 20-amp breakers and four 15-amp breakers, the 8 circuit models have a total of two 20-amp breakers and six 15-amp breakers, and the 10 circuit models have four 20-amp breakers and six 15-amp breakers.
What is the maximum load on EACH LEG?
The watt meters on a transfer switch allow you to balance the load on EACH LEG in order to gauge how much capacity is being used and to maximize generator performance. See the chart for each series to see what the actual limits are. Generally, see the typical switches below.
20 (5000 watt) amps for the 6-circuit. |
30 (7500 watt) amps for the 6-circuit. |
30 (7500 watt) amps for the 10-circuit. |
30 (7500 watt) amps for the 8-circuit. |
No meters are needed for balancing on the 4-circuit models since they have only one leg. On other models wattmeter’s can be added by installing the optional Watt Meter Panel |
Can I connect my water heater, electric range or central air conditioner/heat pump to a transfer switch?
Yes . Items such as a water heaters, central air conditioners or electric ranges can be powered through a transfer switch if the breakers used to control these appliances are adequately rated. Do not try to run these appliances on underrated switches or breakers or you will burn up the wiring, weld the switches, trip the circuit breakers and you will void the switch warranty.
What type of connection is required to connect my generator to my Reliance Pro/Tran® transfer switch or Power Inlet Box?
A four-wire, twist lock connector is needed. We supply suitable power cords with a male connector on one end and a female connector on the other end. The four wires consist of two 120-volt "hot" lines, one neutral and one ground.
Can I hard-wire my transfer switch instead of using a power cord?
Yes. Even the cord-connected models can be hard-wired. Use the cover plate supplied with every unit to cover the inlet hole.
A qualified electrician may be able to install the other standard transfer switches in a hardwire configuration, however, this will void the UL and CSA Listings, and will therefore void the warranty. In addition, if an accident occurs with a unit that has been improperly installed (voiding the UL listing); this may void any insurance claim made after the accident.
Can I use a generator whose wattage exceeds the wattage on the Transfer Switch?
Yes. This is acceptable for peak wattage but not recommended for running wattage. . As long as you do not pull more than the maximum wattage through the transfer switch at one time while in the generator mode. The two wattmeter’s can help you determine how much wattage you are using, and can help you balance the load on each leg in the generator mode. Pulling more than the rated wattage through the transfer switch could burn out the watt meters, burn out the neutral wire, overheat the main wiring in the transfer switch and cause a fire. To insure proper safety precautions, a suitable double pole breaker should be installed between the generator and the transfer switch when the running wattage of the generator exceeds the rating of the transfer switch.
What happens when the Utility Power is restored?
When your utility power is restored, other lights and appliances in your home (not connected to generator power) will turn on, alerting you go to the transfer switch and flip the switches back to "LINE" mode and shut down your generator. Since those circuits using generator power are isolated from the rest of the house, there is no danger of back feeding the utility power.
How long does it take to install a transfer switch?
About an hour by a qualified electrician familiar with residential wiring electrical codes. If installed with a power inlet box, the installation could take slightly longer. Since each unit is pre-wired, the installer simply needs to determine which circuits will be needed in an emergency/outage, wire each set of wires in the transfer switch to those circuits, install the neutral and the ground, and test the installation under load.
Where can I find a 200 amp Double-Pole, Double-Throw switch?
To install a switch of this type, it is usually, necessary to have your local utility pull your meter, and shut off power to your home for several hours during installation. Reliance developed a transfer switch that is installed after the mains for faster, easier installation resulting in a much lower cost. The only limitation with this method is that you cannot have all your circuits in your main panel available for generator power; a limitation most people feel is not a problem. For those that do, Reliance has developed the Panel/Link® TW Series as a less expensive alternative to the double pole transfer switch. The TW Series can transfer either 150 amp or 200 amp service and will handle generators up to 30 kW. Contact the factory for more information.
Why are generators rated in watts when most electric tools are labeled in amps?
Generators are rated by output in wattage which takes into account the amperage at both 120 and 240 volts. NOTE: Volts x Amps = Watts (i.e.: 10 amp motor x 120 volts = 1200 watts continuous + starting watts) OR Watts/Volts = Amps.
Can I make a make a splice in my main breaker panel?
Yes . Under most conditions. Article 373-8 of the National Electrical Code states "Enclosures for switches or over-current devices shall not be used as junction boxes, auxiliary gutters, or raceways for conductors feeding through or tapping off to other switches or over-current devices, unless adequate space for this purpose is provided. The conductors shall not fill the wiring space at any cross section to more than 40 percent of the cross-sectional area of the space, and the conductors, splices, and taps shall not fill the wiring space at any cross section to more than 75 percent of the cross-sectional area of that space."
How does a Reliance Panel/Link ® manual transfer panel differ from a standard Load-Side® transfer switch?
The transfer panel accommodates from 4 to 36 circuits, is designed for use with higher capacity, medium-duty generators, up to 30 kW, and installed like a "sub-panel" after the Main. The branch circuits you want to run on the generator must be relocated from the main panel to the transfer panel. Each Panel/Link® transfer panel includes one utility breaker and one generator breaker, but the individual circuit breakers are generally not provided. The exception is the TRC Series suffix "P" panel which comes with 12 pre-wired circuits including the branch circuit breakers. Reliance also has a full line of Generator-Ready™ Main Breaker Panels that are ideal for new construction or when an electrical service is upgraded. The TW Series is ideal for making your entire existing panel available to generator power.
What are the available configurations of the Panel/Link®?
There are many configurations of the Panel/Link® line. The TR Series Type C (TRC Prefix) is as follows, each available with a range of generator and utility breakers:
"A" SUFFIX- Includes 2 watt meters and power inlet. |
"B" SUFFIX - Includes only the power inlet. |
"C" SUFFIX - Includes only the watt meters, no power inlet. Designed for hard-wiring. |
"D" SUFFIX - Include neither watt meters nor power inlet. Designed for hard-wiring. |
All of the above with an additional SUFFIX "P" - Includes all branch circuit breakers and all the necessary wiring and conduit. Different breaker combinations are designated by a number following the suffix "P" such as "P1".
Other models include smaller and larger sub-panels in the TR Series, 150 and 200 amp transfer panels, and 100, 150 and 200 amp main breaker panels with up to 36 branch circuits. Meters are available as an option on all main breaker panels up to 60A. An inlet can be added to main breaker panels with generator breakers up to 50A using the optional Power Inlet Kits (see accessories section). |
Are the individual circuit breakers included with the transfer panels?
With the Suffix "P" Models only. See question above. Otherwise, the owner or installer must provide the individual branch circuit breakers necessary for installation.
What type of circuit breakers can I use on the Panel/Link®?
All Reliance Panel/Link® transfer panels are UL Listed for use with the following interchangeable branch circuit breakers: |
Siemens Type QP, QT, QPH, HQP, QPF, QPHF, QFP, QE, QEH |
Square D Series HOM (100A Max.) |
Murray Type MP |
Westinghouse Series BD, BR, BQ, GFC (All 100A Max.) |
Which Power Inlet Box can I use with a transfer panel?
You may use any Power Inlet Box up to 50 amps that are available through Reliance.
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