Voltage on PSU? Red switch?

SyncroScales

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Jan 1, 2011
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Hi. I have a PSU. There is a red switch at the back. I live in Canada. What should the switch be set at? What will happen if I change it? From reading, it seems some peopel can change them, and I always leave it alone.

The PSU is older a 300W unit from 2006.
 
I'm Canadian, too. I guarantee your standard household outlet is 120 VAC. The total supply to your house is often called 120 / 240 VAC with Grounded Neutral. That is so certain high-power appliances (stove, electric dryer, electric water heater, central A/C) can be wired for the 240 VAC supply, but ALL standard wall outlets and light fixtures are 120 VAC, usually on circuits with a 15 amp breaker. It's the same system as in the USA, although various provinces and states have small details different.

Set your PSU switch to 120.
 

Isn't an electic cooking range and electric clothes dryer considered normal North American appliances? They both have 240 Volt plugs and require a 240 Volt outlet.

If you're recharging your electric vehicle it's quicker to use a 240 Volt outlet.
 


Well, yes, I guess so, lol, but I was talking about TV's, microwaves, refrigerators, and other smaller electronics. I'm pretty sure that it's a forgone conclusion that an oven and dryer are different (if you know ANYTHING about household appliances), so that's why I didn't make that distinction.
 

That's a NEMA 5–20R receptacle used when wiring a single receptacle on a 20 Amp circuit.

What you're use to seeing is the NEMA 5-15R, the most common electrical outlet in North America.
 
In many Canadian provinces, standard wall outlets are rated at 15 amps and the outlets look like the ones you are used to, with two parallel vertical slots (one larger than the other) and a third round hole for Ground. An outlet for 20 amps (with appropriate wiring in the wall and breaker rating) has the left slot horizontal, instead of vertical. This ensures that you don't try to mix up sockets with devices with different requirements. Although the link may not be obvious (see below), there is another type of outlet used in Canada and elsewhere known as a "split duplex" receptacle, that looks exactly like the ones you are used to. But inside and in the wiring, it's a little different so that each half (top and bottom) is on a separate 15 amp breaker. Thus, you can plug TWO high-power devices (up to 15 amps each, like a toaster and a microwave) into the two halves and they both work just fine. These are required in certain places in a kitchen where you are likely to use many appliances.

In many states of the USA, they have a different solution to this need for plugging in several devices in a kitchen. They use the type of outlet you have pictured, which is designed to allow you to plug in EITHER a 15-amp plug or a 20-amp plug - both will fit. The wall wiring and breaker are rated for 20 amps. BUT both upper and lower halves of the duplex outlet are off the same 20-amp breaker, just like our 15-amp duplex outlets. Thus you CAN plug two high-power appliances into this duplex outlet and they will work IF the total current is less than 20 amps. If it's more than that (say, two 13-amp loads at once), the fuse will blow. Not quite as sure to work as a split duplex 15-amp outlet, but it usually works OK. And since the wiring is really capable of 20 amps anyway, the outlet is configured to allow a proper 20-amp plug and device to be plugged in. The other "weakness" of this compared to the duplex 15-amp system is that you are able to plug a 15-amp device into a circuit protected by a 20-amp breaker, so it is possible for that devices' internal wiring to be overloaded without tripping the breaker. On the other hand, the breaker and wiring for this 20-amp circuit is a bit cheaper, and it consumes one less breaker position in a breaker box.