First, lets discuss what GFCI protected means. GFCI stands for ground-fault circuit interrupter. You will recognize the outlets in your home, they are the ones with test and reset buttons. This is to eliminate the risk of an electric shock. On many of our generators, GFCI protection is part of the main line circuit breaker.
You can use a transfer switch with a full panel GFCI protected generator. When looking at transfer switches, you will need one with a switched neutral.
3-POLE SWITCHED NEUTRAL
A 3-pole transfer switch with a switched neutral is single phase. The switching mechanism will break the two hot legs of the circuit, in either direction, before the neutral is broken. It will then close the neutral before the two hot legs close, preventing the generator’s circuit breakers from nuisance tripping and protects inductive motors and sensitive loads.
This style of switched neutral transfer switch is also recommended for safe use with any generator that has a bonded neutral.
When you think of an item being “secure”, like us, you probably think that something is lockable. In most circumstances, you are right. However, when ASCO says their switch has a secure enclosure, they are saying that the enclosure has extra protection from UV rays. All ASCO transfer switches require a key, tool or both to gain access to live parts. Not all ASCO transfer switches are protected from potential harmful effects of UV radiation.
Non-Secure
These enclosures have a single door access to the inside equipment. Controls and displays are mounted in the door, thus they are exposed to direct sunlight and other environmental conditions.
If you are installing the transfer switch in an area where UV protection isn’t a main concern, the non-secure enclosure would be a great choice.
Secure
Secure enclosures have a door-over-door construction, therefore, protecting the controls and displays from sunlight with some extra protection from precipitation.
Solar Radiation Exposure Map
High UV radiation levels, extreme temperatures, and conditions such as elevated humidity, high altitude, and air pollution, may increase the rate of degradation of display and control materials.
A transfer switch can be damaged or create dangerous conditions if it is exposed to dirt or water. Therefore, it is essential that the transfer switch has an enclosure designed for the location and the risks it will be exposed to.
NEMA stands for National Electrical Manufacturers Association. NEMA represents nearly 325 electrical equipment and medical imaging manufacturers who make safe, reliable, and efficient products and systems.
For those who like the full technical definition keep reading. We included some pictures for the visual learners.
NEMA 1
For indoor use only.
The NEMA 1 enclosure protects personnel from gaining easy access to hazardous parts. Also, it will protect the equipment inside the enclosure of falling dirt.
NEMA 3R
For indoor or outdoor use.
The NEMA 3R enclosure protects personnel from gaining easy access to hazardous parts. Also, it will protect the equipment inside the enclosure of falling dirt, and the formation of ice. It also has an ingress protection of rain, sleet, snow.
NEMA 4
For indoor or outdoor use.
The NEMA 4 enclosure protects personnel from gaining easy access to hazardous parts. Also, it will protect the equipment inside the enclosure of falling dirt, windblown dust, rain, sleet, snow, and the formation of ice. It also has an ingress protection of splashing water, hose directed water.
NEMA 4X
For indoor or outdoor use.
The NEMA 4X enclosure protects personnel from gaining easy access to hazardous parts. Also, it will protect the equipment inside the enclosure of windblown dust, rain, sleet, snow, additional level of protection against corrosion, and the formation of ice. It also has an ingress protection of splashing water, hose directed water.
NEMA 12
For indoor use only.
The NEMA 12 enclosure (without knockouts) protects personnel against access to hazardous parts. Also, it will protect the equipment inside the enclosure of falling dirt, circulating dust, fibers. It also has an ingress protection of dripping and a light splashing of water.
Where you install the transfer switch will depend on the type of switch and what type of generator you will be using. The following installations will work for both manual and automatic transfer switches.
Emergency Distribution:
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The transfer switch is installed between a main panel and a sub panel. The main panel connects to the non-essential loads. The sub panel connects to the essential loads. In the event of an outage, the transfer switch will only transfer power to the essential load panel.
This type of installation allows you to purchase a smaller generator and a smaller amperage transfer switch. As a result, it will keep costs down.
Full Load (Non-SE Rated):
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The transfer switch will be located after the service disconnect panel of the building. There is the option to manually switch breakers off on any load you do not want to power.
You will want to size your generator and transfer switch amperage to match the load.
Full Load (SE Rated):
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An SE rated transfer switch has a service disconnect breaker installed. Therefore, the switch will be installed directly to the utility power entering the building. The main panel will have the essential loads connected. There is the option to manually switch breakers off on any load you do not want to power.
You will want to size your generator and transfer switch amperage to match what will be powered with the generator.
Multiple Services:
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One generator can provide backup power to multiple services. You can install the transfer switches in any variation of the three installations mentioned above.
You will want to size the generator large enough to run normal loads and start large motors.
Transfer switch as a Load Control Device:
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Starting large motors at the same time will require a large generator to deal with the inrush. A cost effective solution is to install multiple transfer switches. By setting the transfer delay in staggered intervals each load will be added to the generator separately reducing total inrush. You can install the transfer switches in any variation of the three installations mentioned above on each load.
Be sure to size the generator so it will be able to run all connected loads and also have enough amperage to start the last motor.
Manual and automatic transfer switches are an important accessory when it comes to safely switching from utility power to backup power.
How they work
1. Manual transfer switch
When the power fails you need to get your generator set up. Normally you wheel it outside an place it where exhaust fumes cannot seem into windows, doors or vents. Next you need to connect the power cord between the generator and transfer switch. Once you have the generator running you will go to the transfer switch and manually switch from utility to generator power. Once you notice the utility power is back on you reverse the process.
2. Automatic transfer switch
The transfer switch will detect a utility failure and send a signal to the generator to start up. When the generator is at the correct voltage, usually within about 10-30 seconds, the transfer switch will connect power.
As soon as utility power is detected, the switch will signal the generator to shut down, and switch back to the utility power source.
Pros and cons of each system
1. Manual Transfer Switch
Pros –
Your generator is most likely a portable generator and you will be able to move it around.
Cost effective.
You have full control.
Cons –
You have to be present to switch between power sources.
More work.
Requires a little technical skill.
You can run on generator power long after utility power is restored if you aren’t paying attention.
2. Automatic Transfer Switch
Pros –
Easy to use.
You do not have to be on site.
Automatically tests itself.
Less down time between transfer.
Cons –
More expensive.
Generator is permanently mounted.
Matching a transfer switch to a generator
Manual and automatic transfer switches can work with any type of generator. Generally, if you have a portable, towable, or PTO generator, you will select a manual transfer switch. Standby models, such as our PSS or diesel units, you will use an automatic transfer switch. If you have any questions or concerns, give us a call or contact your local electrician.
