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Discussion Starter · #1 ·
Just had a quick question on a single pole double throw switch. I know that it is when the switch is flipped one way one load is turned on and the other is off. Then when it is flipped the other way the one load is off and the other is on. I'm confused when I have to do this with three loads. My question says "three small appliance receptacles are controlled by a SPDT switch." I didn't know how to make it work with three. Any help would be great, thanks.
 

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If you connect the line to the common terminal and switch leg to one of the remaining two terminals(nothing on the third) you now effectively have a single pole switch. You can now turn them all on and off at once. This might not be what the question is asking but you weren't too clear.

You could also have two receps on one side and one on the other.
 

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Discussion Starter · #5 ·
I am a junior in high school taking a vocation class. Sorry for not phrasing correctly. My teacher gave me these specs: "Three small appliance receptacles are controlled by a spdt switch that is energized by the load side of a GFCI receptacle. This circuit is one of two circuits that come from the 240 volt 100 amp 20 circuit panel." What we have been doing is making diagrams for all of our circuits. I hope this clarifies my question.
 

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The spdt switch can only interrupt two appliances. (And you can not have both on at the same time.) If the spdt switch was powered from the line side if the GFCI receptacle then the third appliance could be controlled by tripping the GFCI. The problem with that is the two appliances controlled from the spdt switch have no ground fault protection.

Seems like a silly question to me.:001_huh:
 

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I don't think they are saying that the 3 appliance outlets are on separate circuits. I read it as the 3 appliance outlets are on the same circuit, on the load side of the GFCI.

Use the single pole switch to switch both the hot line from the GFCI to the appliance outlets. As Vintage Sounds said, connect the line (hot) from the load side of the GFCI to the common switch terminal and switch leg going to the appliance outlets to one of the remaining two terminals (nothing on the third).
 

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Why would you use a SPDT switch?? All you need is a SPST switch.
Just to add a variable to the problem. It will confuse those that really don't grasp the concepts. Those who do get it, know how to use a SPDT switch in a SPST application (due to color matching, I've had to use a 3-way (SPDT) in a standard (SPST) switch application).
 

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I've always hated these types of word problems. They never make any sense and require too many presumptions.

Basically this. To the OP, any number of diagrams you draw could be characterized as "correct."

This isn't a terribly realistic problem. Perhaps the instructor just wants to know if you understand certain concepts. Kitchen small appliance circuits are generally constantly fed, as opposed to being switched.

Here's one possible configuration, as was mentioned previously:

Connect the load side of the GFI to the common on the switch. Connect one of the "throw" terminals on the switch to the first in the daisy chain of receptacles. Done.

Essentially, this is a stupid question, so just get it done and move on.
 

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. My teacher gave me these specs: "Three small appliance receptacles are controlled by a spdt switch that is energized by the load side of a GFCI receptacle. This circuit is one of two circuits that come from the 240 volt 100 amp 20 circuit panel." .
Tell your teacher that 220 said to use real life examples in his questions. :jester:
 

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I am a junior in high school taking a vocation class. Sorry for not phrasing correctly. My teacher gave me these specs: "Three small appliance receptacles are controlled by a spdt switch that is energized by the load side of a GFCI receptacle. This circuit is one of two circuits that come from the 240 volt 100 amp 20 circuit panel." What we have been doing is making diagrams for all of our circuits. I hope this clarifies my question.
You are reading too much into this, which is likely the intent of the question; to get you to simplify OR to know that you need to ask more questions!

There is nothing in the way the question is worded that implies that the devices must work ALTERNATELY! You just have a switch feeding a circuit that has 3 outlets on it.
 

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When I think of a spdt switch, I am thinking of a toggle switch that has three positions.

Up= on load 1
center= off
down= on load 2

Not like the 3 ways we use all the time, which I guess could be called a spdt.
 

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I think the question mentioning the panel is a red herring as well as the switch type. It talks about three "*small* appliance" receptacles which would presumably be 120v, given that they are fed from the load side of a GFCI in a kitchen.

This is a case of too much information presented and it is the student's job (as it would be in the real world dealing with a talkative customer) to parse out the info and consider (ask if not clear) the actual goal. In this case, it sounds like the goal is to switch three 120v kitchen receptacle on/off from one switch. One side of the switch and the common terminal will do it. The other is unused.

Remember- the simplest answer is usually the most correct.
 
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