Transfer Safety Switches & Code Requirements
The major ice storm in January 2005 was the worst outage ever experienced by your cooperative. Since then, many Firelands Electric members have called to inquire about standby generators. Their questions range from what size generator is required to what is needed for a proper and safe installation.
Firelands Electric Cooperative carry several styles of transfer safety switches. This equipment is only sold to members of the cooperative. Transfer safety switches become property of the member (as is any equipment beyond the weather head).
All of the switches described below will allow for the safe operation of an emergency generator. Your particular needs and size of service dictate the type of switch you should purchase.
Here are several important points about the installation of a double-throw or transfer switch:
Figure 1 -- Typical Double-Pole, Double-Throw Transfer Switch
The double throw transfer switch is installed under or in place of the customer’s meter base, before the entrance cable enters the building to the breaker panel. This switch will allow the operation of any circuit in the breaker panel—up to the limitation of the generator’s capacity. Double throw transfer switch installations for 120/240 V, single-phase service, must be bonded according to National Electrical Code requirements and local regulations:
- The double throw or transfer switch must have a capacity (100AMP or 200AMP) equal to or greater than the capacity of the breaker panel (i.e., if you have a 200AMP breaker panel you must use a 200AMP transfer switch.
- Firelands Electric will only install the double throw switch on the exterior of the building or on the meter pole. The double throw switch is normally installed at the meter location. The member is responsible for assuring that the point of attachment is substantial enough for the switch to be secured to the building or meter pole.
- The double throw switch will allow the member to safely energize any circuit in the house with an emergency generator while assuring that the generator cannot back-feed into Firelands' power lines. The number of circuits that can be energized at one time is determined by the output capacity of the customer’s generator.
- Although the double throw and transfer switch/meter base combination is more costly, it is highly recommended. This combination has a much better appearance and should eliminate the problem of shifting the meter base on the house to allow room to install the double throw switch. Although the double throw or generator switch/meter base combination will usually cover siding, holes or marks left from old equipment, there may be some instances when it will not. If this occurs, Firelands will not be responsible for repairs.
For single-phase, 120/240 volt power, the transfer safety switch should be a double-pole, double-throw type. Double pole means that there are two pairs of wire lugs available for connection of hot conductors. The third wire (neutral wire) is continuous through the transfer enclosure, and is typically not switched (NEC Article 230-83). The ground wire also passes through the switch enclosure to provide a safe and continuous ground connection.
A three-phase generator would require a three-pole, double-throw switch. Some electric services use current transformer (CT) metering. This may require the use of a pole-top transfer safety switch. The operation of these switches is essentially the same, except that an extended manual switch lever is needed to allow the user to operate the switch from ground level.
Figure 2 -- Double-Throw Switch, Controlling Individual Circuits
The term double-throw means that the operator can place or "throw" the switch into two different positions. One position feeds power from the utility system to the load. The other position feeds power from the standby generator to the load. Such a switch will prevent electricity, generated by the standby unit, to flow simultaneously to both the customer's home or farmstead, and to the utility's system. This is essential to protect utility personnel and to prevent generator equipment damage.
Figure 3 -- Generlink Safety Device
Firelands offers the new GenerLink safety device, which provides convenience and security to members using standby generators.
GenerLink is a transfer switch that isolates your generator from the cooperative's power lines whenever your generator is generating electric current. This prevents your generator from backfeeding current onto our lines and endangering the lives of our personnel. If you do not have a double-pole/double-throw switch installed, the backfeed from your generator onto the main electric lines could seriously injure or kill personnel as they try to restore power -- even if you are miles away from where line crews are working.
Firelands Electric offers a simple, safe and reasonably priced device to allow you to connect a standby generator to your home's electric system at the electric meter. The GenerLink makes it easy to connect your generator and supply standby power (maximum of 30AMP) to any circuit in your home. The GenerLink is a meter collar device that is installed by Firelands' technicians behind your electric meter.
You simply plug one end of a power cable into the Generlink and plug the other end into your generator. When your generator is running, the GenerLink automatically disconnects your home from Firelands' main electric lines -- preventing hazardous backfeeds. It also protects your generator from being damaged when the main line power is restored.