Safe low voltage

The closest I know of might be, step and touch potentials as used in power distribution, building, and transit trades. And in my experience all of those vary depending on locality/property. Anything from 40V to

80V are numbers I'm used to seeing in specs. In past attempts I have been unable to trace these to a national or international standard.

Would you feel better about your 60VDC if it was balanced around ground?

Tim.

According to

, "Hazardous Energy Level

A stored energy level of 20J or more, or an available continuous power level of 240 VA or more, at a potential of 2V or more.

Hazardous Voltage

A voltage exceeding 42.4V peak or 60V d.c., existing in a circuit which does not meet the requirements for either a Limited Current Circuit or a TNV Circuit."

This was the first of "about 97,600" results on

It might be different in different countries.

Hope This Helps! Rich

Not a lot:)

I'll order the up to date IEC standard tomorrow. £234 or about $375. Expensive at half the price.

Indeed, 36V DC has been fatal in at least one instance.

Slot-cars and model trains run at about 12V, and _some_ people find contact with that unplesant.

Those halogen lamps with exposed wiring also seem to use 12V bulbs (but probably AC)

Apple's magsafe chargers may have exposed 16.5V contacts.

--
?? 100% natural

48VDC is a common backup system voltage.

The deal with AC is if you pass the current from arm to arm, it tends to make the heart pump at 60Hz if the current is sufficient. If you just touch AC mains with one hand, the risk is more from the jolt your body makes as you pull away. Of course kids, don't try this at home.

All that said, I don't know when DC is really dangerous, but for something you are not going to sell and it is going to be used in a lab environment by people who aren't drooling, I doubt going up to

60VDC is much worse than 48VDC.

Testing a 4.5 V or 9 V battery with your tongue can be a bit uncomfortable, if the battery is still fully charged :-).

The problem with dc is that the muscles tend to lock on to what is being gripped, whereas ac tens to throw you off. Hv dc has always been recognised as the greater danger, especially across the chest.

As someone else said, you can isolate or even centre tap to halve the effective voltage to gnd, which I what do for the lab ac supply. 3Kva

240->240 isolation transformer, with centre tap to ground, also allows the use of 115volt kit as well.

I think the latest auto design thinking is for a 42 volt bus, whereas telco kit is rated at 40-60 volts. This takes care of lead acid cell bank discharged / on charge. I wouldn't want much more than that floating around anywhere in the lab and that's from hard learned lessons in the old days with valve (tube) equipment...

Regards,

Chris

So DC stops your heart and AC beats it to death. I think I'll pass on both!

Mercedes was pushing 42V. However, the higher the voltage, the greater the chance of battery failure since it takes more cells.

I was digging through a surplus shop today. Lots of 48V to "whatever" supplies, but mostly PC type.

I've had to design to IEC61010 too and my understanding is that:

any current is OK (for electrocution purposes) up to 42.4V dc or the equivalent AC. My suspicion is that this level was chosen because there are a lot of 24V AC power buses in industrial equipment, with a 10% tolerance. That just happens to be 42.4V peak. Note that high currents begin to impact choice of connectors, wire etc which must be rated by a recognised body as fire-safe at that current.

Above that voltage you need to limit the current, OR use special connectors which are inaccessible to standard fingers; and there are further complications if the area is wet, etc.

I've not designed medical stuff, but I think the limit on things attaching to (or perhaps implanted in) the body is just 6V, which gives you an idea of how sensitive our bodies can be in the wrong conditions.

Just received the 2010 standard. For normal conditions it states 33V rms, 46.7V peak and 70V dc.