Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: Willabe on February 12, 2016, 11:55:52 am
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Should I be using a GFI wall outlet in my work shop and an ISO PT for any amps I'm working on?
GFI > ISO PT > Variack (when needed) > light bulb limiter (when needed) > amp
And should my oscilloscope (and signal generator, when I finally buy 1) be plugged into the same GFI and the ISO PT when I use it?
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GFI
Not sure if you gain anything because of your iso, they *sense* issues tween ground - neutral(?) and your iso I believe *isolates* your bench ground from house ground. IF you try, make sure your wires from *bench* to *box* are correctly wired
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I believe a GFI is a smart thing to put in your workshop. I've worked in industries were all power tools needed to be gfi'ed. I have even seen electrical inspectors cite someone because their coffee pot was not grounded.
To me, the key word is "workshop"
Could suggest a quad box where, one half the box is not GFI'ed, just in case, some of your electronics do not like the GFI.
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> just in case, some of your electronics do not like the GFI.
On the one hand, most stuff that "does not like GFI" is defective, should be fixed or replaced.
Large (>1/2HP) motors are a traditional exception, because of the high starting current (>40A). This requires 1000:1 balance of the lines to avoid crossing the 50mA short-term trip of a US GFI. Some older wires (and GFIs) were not that perfect. Yet I have been running large motors on GFIs, no problem except when a plug was in the mud (then it should trip!).
That said.... I just took one device off a GFI and I am thinking about another.
The furnace quit. It drips (condensing) so has a small pump to lift the condensate out of the cellar. The pump was dead. I'd wired it to kill furnace before it overflowed on the floor. Furnace was non-GFI but pump was GFI. Random trip? Annoying, and there isn't that much danger (pump is all plastic). I moved the pump to a non-GFI outlet. (Still have GFI right-there for worker power tools.)
The internet went out. The modem-thing is in the cellar, so GFI had seemed wise. But I had been working around it, the plug overlaps the test button, and apparently I had bumped it enough to trip-out the GFI and kill the internet. For now I use a different plug, but I just may mount a network-only non-GFI outlet high in the joists, where it can't be used casually for lamps or vacuums. Leave the existing GFI where it is (chest level) for those things.