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Anything I should know about putting GFCIs at a work bench?
paulca:
My office and workbench are on several RCDs.
The whole house is on a 100mA trip at the 'tails'. The workbench circuit is power off an inverter with mains transfer switch and RCD.
Install them, forget they are there. Maybe, maybe they might save you, but never rely on them.
EDIT: I tested my main RCD in anger accidentally one day. I pulled the fuse for the lights with the intent on cutting the light feed wire for the garage out of the 240V circuit and converting it to 12VDC.
Fuse out I cut through the 1.5mm T&E and Boom, power off. Why?
The cutters shorted N to E, enough potential exists in the voltage drops to cause current to flow. Trip.
EPAIII:
Why on earth would you deliberately provide 1/2 of a circuit that could kill you?
In addition to years as an electronic hobbyist, I worked over 45 years with all types of electric and electronic equipment, including high powered (high Voltage) commercial transmitters. In all of that time the worst shock I ever got was when about 40,000 Volts passed through my body, through my shoes, and into the grounded, METAL workbench I was working at. I know that was the path it took because I found the burn holes in my hand and on the bottom of my foot.
IMHO, the last thing you want is a grounded workbench. And I think I know what I am talking about. I don't even like those grounded mats for the top of the bench that are supposed to prevent static damage. When I find one I either disconnect it or toss it away. In that same time period I have never seen anything damaged by static discharge. Those mats serve NO PURPOSE.
Oh, and when you see a Voltage specification on a probe, BELIEVE IT. That 40,000 V also went through or around a meter probe I was using. The meter, a Simpson 260, was OK.
--- Quote from: LabSpokane on April 07, 2015, 06:28:50 pm ---The US standard GFCI is designed to trip about 5mA, not 30mA. They are an excellent idea. Consider grounding your workbench, etc if it is metal. I specifically chose metal pegboard mounted to Unistrut so that I would have a solid ground in case devices mounted there faulted.
--- End quote ---
watchmaker:
In my "lab" area (corner of the basement) the bench is powered by (2) 12 output switched 120 v strips. These are in turn plugged directly into a GCGI/AFI which is wired to the panel protected by a whole-house surge protector. After burning up two microwaves in Maryland lightning storms, I learned the value of the latter. Also, I found one of my switched machine tools smoking. Had no problems for ten years after that.
I do use an ESD mat/strap on a wooden bench (doors on saw horses, I am a "farmer" at heart); in defense, my setup is temporary as I figure out what I need (MORE space!). But I avoid (emphasis on avoid) probing over 120 vac.
This set did save me when I was troubleshooting a BK501a and I knocked the collector of a high voltage transistor to the grounded frame. The GFCI/AFI reacted in time to save the device and scope and the one-hand rule protected me.
The central switching at the bench is highly convenient, inexpensive, reduces electricity usage, and adds another layer of equipment protection.
As to whether the ESD protection is overkill and risky, I accept current industry practice. This is all as an extremely raw amateur.
soldar:
--- Quote from: free_electron on April 07, 2015, 06:37:21 pm ---arc fault interrupter in the fuse box. gfci in the outlets.
standard breakers work on a thermal principle. create a short : heat up the internal element and they pop
AFCI are magnetic. create a hard short and the current spike sets of a magnetic system the pops the breaker. so these things react to huge inrush currents. if you have an intermittent arc a thermal breaker may 'average out' the current and not trip. an AFCI will trip because the arc current is much higher.
the american power system is retarded.
in europe you can get GFCI + AFCE + breaker in 1 combo element. my parents home is 50 years old and already has such devices installed. AFCI are just now becoming avaialble in the Us but not mandated by code.
same stupidity as running double insulated wire inside drywall ... one rodent and the house goes up in flames. power cables need to run in conduit.
--- End quote ---
I believe you are confusing things.
European and American circuit breakers both can be tripped by a bimetallic element heating up and by a solenoid. The heat element is slower acting and the magnetic element is faster acting. Between the two elements they provide a certain trip time as a function of the overcurrent.
GFCI are generally provided in America at the outlet level whereas in Europe they are generally in the general panel. Each option has its pros and its cons.
And AFCI are ARC Fault Circuit breakers, totally unrelated to the previous ones.
Edit: https://www.realpars.com/blog/circuit-breaker
AVGresponding:
The most important thing to remember when you have GFCI/RCD/RCBO protection is that THIS DOES NOT MAKE YOU SAFE. It only reduces your risk.
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