- #1
zachjen
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I need to replace a switch that has printed on it 3A 250VAC or 6A 125VAC. Is it alright to replace it with a switch rated 3A 125VAC 1.5A 250VAC ? Thank you.
Replacing a 3A 250VAC Switch: Tips and Considerations | Your Guide
- Thread starter zachjen
- Start date
In summary, it is safe to replace the switch with the new one rated for 3A 125VAC and 1.5A 250VAC, as the device will only use less than 50mA. However, it is recommended to use a DC rated switch for low-voltage applications, which can be found at an auto store. Additionally, the separation of contacts in a DC switch needs to be greater than in an AC switch due to the difference in arc stopping capabilities. It is also important to consider the "forming" voltage and polarity when choosing a switch for long-term use.
- #2
Okefenokee
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Yes, no, maybe?
Those numbers are telling you how much power it can handle. The new switch can only handle half the power of the old switch. My prediction: it will work but the new switch will not last very long as it will heat up too much and wear out. It all depends on how much current the load will draw. Since the old switch is kaput, it's safe to guess that the old switch, which was twice as rugged, was overdrawn too.
Those numbers are telling you how much power it can handle. The new switch can only handle half the power of the old switch. My prediction: it will work but the new switch will not last very long as it will heat up too much and wear out. It all depends on how much current the load will draw. Since the old switch is kaput, it's safe to guess that the old switch, which was twice as rugged, was overdrawn too.
- #3
berkeman
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zachjen said:
Where is the switch used? Why are you replacing it?
- #4
zachjen
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It is for a FM modulator to hook up an ipod to my car. I attatched a photo of the package that illustrates what's going on here. The switch labeled switch is what I want to replace(the switch that came with it isn't round like pictured). The reason I am replacing the switch is because it is a rectangle shaped one and I wanted to get a round one because it would be easier to mount it into where I am putting it (just drilling a round hole instead of making a rectangle hole). I had this switch laying and was wondering if it could be used here. So I guess I need to know what ratings to look for to replace this switch.
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- #5
berkeman
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zachjen said:
Ah, that helps a lot. Since it's a low-voltage application, just be sure the switch is rated for the current that it will pass.
- #6
Studiot
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Strangely enough mains switches don't last very long in cars.
You should really use a DC rated switch - you will find these at a proper auto store.
This is because the requirements for contacts etc are totally different for DC switches, life is actually tougher for them.
You should really use a DC rated switch - you will find these at a proper auto store.
This is because the requirements for contacts etc are totally different for DC switches, life is actually tougher for them.
- #7
berkeman
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Studiot said:
No kidding -- I didn't know that. Is there some place I can read more about the differences? Thanks.
- #8
vk6kro
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zachjen said:
This device will only use less than 50 mA, so neither switch would be used to its maximum ratings.
The new switch will work perfectly.
- #9
Studiot
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Seeing your strapline I would suggest looking in one of the weighty tomes produced by the ARRL on components.
I think the RSGB also does something similar, I will try to look it up.
Google sometimes comes up with all sales stuff rather than technical articles and I fear this is a case in point.
I think the RSGB also does something similar, I will try to look it up.
Google sometimes comes up with all sales stuff rather than technical articles and I fear this is a case in point.
- #10
zachjen
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perfect. Thanks alot!
- #11
berkeman
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Studiot said:
Thanks, I'll do that when I get home tonight.
- #12
vk6kro
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Because an AC arc stops when the polarity reverses and a DC arc cannot do this, the separation of the contacts in a DC switch has to be greater than for an AC switch at the same operating voltage.
However, this is a 250 volt switch being used at 12 volts and it is being used at less than 5% of its rated current, so there is no problem with using it.
However, this is a 250 volt switch being used at 12 volts and it is being used at less than 5% of its rated current, so there is no problem with using it.
- #13
Mike_In_Plano
- 702
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In a prior life, I was in the HVAC designing business, and we had two issues with relay contacts.
One was the "forming" voltage. Essentially, you need a minimum amount of current and voltage to keep the contacts clean. The silver alloy contacts used in power relays will otherwise build up a layer of oxide and fail.
The other issue was related to polarity. Our microcontrollers were programmed to close / open the relays independent of line phase. Otherwise, continual operation at one point of the line phase can prematurely erode the contacts.
One was the "forming" voltage. Essentially, you need a minimum amount of current and voltage to keep the contacts clean. The silver alloy contacts used in power relays will otherwise build up a layer of oxide and fail.
The other issue was related to polarity. Our microcontrollers were programmed to close / open the relays independent of line phase. Otherwise, continual operation at one point of the line phase can prematurely erode the contacts.
1. What is an "Idiot with a simple question"?
An "Idiot with a simple question" is a phrase used to describe someone who may not have a lot of knowledge on a particular topic and is asking a basic or straightforward question. It is meant to be a lighthearted way of acknowledging that everyone has to start somewhere and that it is okay to ask questions.
2. Why do people use the term "idiot" in this context?
The term "idiot" in this context is not meant to be derogatory or insulting. It is simply used as a way to acknowledge that the person asking the question may not have a lot of knowledge on the topic and is asking a basic question. It is not meant to be taken literally or as a reflection of one's intelligence.
3. Is it okay to ask "simple" or "basic" questions as a scientist?
Yes, it is absolutely okay to ask "simple" or "basic" questions as a scientist. In fact, asking questions is an important part of the scientific process. It shows curiosity and a desire to learn, and can lead to new discoveries and advancements in the field.
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If someone calls you an "idiot" for asking a simple question, it is important to remember that their comment is not a reflection of your intelligence or worth. You can calmly explain that you are simply seeking clarification or more information on the topic, and that everyone has to start somewhere. It is also important to remember that it is okay to walk away from a conversation if it becomes disrespectful or uncomfortable.
5. Is there such thing as a "stupid" question in science?
No, there is no such thing as a "stupid" question in science. Every question has value and can lead to new insights and understandings. What may seem like a simple or basic question to one person may be completely new and thought-provoking to another. It is important to create a supportive and inclusive environment where all questions are welcomed and encouraged.
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