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Discussion Starter #1
Hi

I'm in IT but I do fix minor electronic things sometimes, so I bought a 30V 5A bench power supply, my questions:

1- How dangerous is to work with such power supply?

2- My bench is covered with Anti-Static grounded mat, is that a good idea to work on or not?

3- Should my legs touch ground while I'm working or I better be isolated from ground?

I know those are basic questions, but I'm not electrical so I better know.
 

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A 5V 30A supply poses no shock hazard at all (as long as the 120V input wiring is not exposed). It can start fires and heat things up very quickly in case of a short circuit though. You can work on an anti-static mat, but if you are working with circuits that are sensitive to small leakage currents the mat may be a problem. They are really designed for handling electronics, not testing them. Your isolation from ground is irrelevant at 5V. It makes no difference aside from static dissipation.
 

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Discussion Starter #3
I'm talking about 30V 5A not 5V 30A! Is your answer still valid?

A 5V 30A supply poses no shock hazard at all (as long as the 120V input wiring is not exposed). It can start fires and heat things up very quickly in case of a short circuit though. You can work on an anti-static mat, but if you are working with circuits that are sensitive to small leakage currents the mat may be a problem. They are really designed for handling electronics, not testing them. Your isolation from ground is irrelevant at 5V. It makes no difference aside from static dissipation.
 

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1. It isn't. As mpoulton said, the only way it can hurt you is if you heat something up and burn yourself on it. If you properly set your Imax relative to your load you can't even do that.

2. The mat and other ESD equipment has many megohms impedance to ground to ensure you can't be hurt even if you come in contact with line voltage while touching it. The output(s) on your supply won't even be referenced to ground unless you intentionally do so (that's what the green grounding terminal is for).

3. Even at 30V fully referenced to ground it isn't an issue. Work with your bare feet on the ground or work standing on a 10 kV insulating sheet. Anything in between is OK, too.
 

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Discussion Starter #5
Thank you,
so even at 5A is safe? I mean 30V with max 5A?

1. It isn't. As mpoulton said, the only way it can hurt you is if you heat something up and burn yourself on it. If you properly set your Imax relative to your load you can't even do that.

2. The mat and other ESD equipment has many megohms impedance to ground to ensure you can't be hurt even if you come in contact with line voltage while touching it. The output(s) on your supply won't even be referenced to ground unless you intentionally do so (that's what the green grounding terminal is for).

3. Even at 30V fully referenced to ground it isn't an issue. Work with your bare feet on the ground or work standing on a 10 kV insulating sheet. Anything in between is OK, too.
 

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I'm talking about 30V 5A not 5V 30A! Is your answer still valid?
Yes, perhaps even more so because 5A is less of a burning hazard than 30A. You can feel a small tingle from 30V under the right circumstances, but it's not a high enough voltage to be harmful unless you somehow jam electrified needles through your skin - so just avoid doing that and you'll be fine!
 
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Generally, the risk of such a supply is low, but make sure water stays away from your workbench – even coffee. Even low voltages can be dangerous in contact with wet skin. Other than that, as previous commentators have said, the main risk is starting fires: 30v x 5a = 150 w, and that, if shorted, is more than enough to heat wire red hot in a minute or two, if not less.
 

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Discussion Starter #8
What about human shock with 30V 5A regardless fire risk! Is it dangerous?

Generally, the risk of such a supply is low, but make sure water stays away from your workbench – even coffee. Even low voltages can be dangerous in contact with wet skin. Other than that, as previous commentators have said, the main risk is starting fires: 30v x 5a = 150 w, and that, if shorted, is more than enough to heat wire red hot in a minute or two, if not less.
 

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JOATMON
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What about human shock with 30V 5A regardless fire risk! Is it dangerous?
You will be fine. It might tingle a little if you stick your tongue to the wires, but otherwise, no danger.
 

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Keep yourself and your shop dry and treat electricity with respect and you should be fine; turn off the power supply when you are working on the connections and so on.

Don't be careless, though, and do not put 30v through your tongue! I haven't tried the experiment, and I suspect it would hurt a lot, if not burn quite seriously.
 

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JOATMON
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Keep yourself and your shop dry and treat electricity with respect and you should be fine; turn off the power supply when you are working on the connections and so on.

Don't be careless, though, and do not put 30v through your tongue! I haven't tried the experiment, and I suspect it would hurt a lot, if not burn quite seriously.
he would only do it once
 

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Discussion Starter #12
Thank you, I work with my hands so I won't try the tongue thing for sure :vs_laugh:

Keep yourself and your shop dry and treat electricity with respect and you should be fine; turn off the power supply when you are working on the connections and so on.

Don't be careless, though, and do not put 30v through your tongue! I haven't tried the experiment, and I suspect it would hurt a lot, if not burn quite seriously.
 
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