A lot of people on this forum swear by Variacs. A simple and likely dumb question. Would the Variac plug into the GFCI, or would you put the GFCI(s) on the output side?
3 posters
Variacs and GFCIs
deepee99- Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho
corndog71- Posts : 840
Join date : 2013-03-19
Location : It can get windy here
deepee99 wrote:A lot of people on this forum swear by Variacs. A simple and likely dumb question. Would the Variac plug into the GFCI, or would you put the GFCI(s) on the output side?
Well, think about it this way: Whatever you plug into the GFCI will be protected by the GFCI. If you want to also protect your variac then plug your variac into the GFCI.
deepee99- Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho
Thanks. The reason I asked was I had a variac that developed a ground fault all on its own...corndog71 wrote:deepee99 wrote:A lot of people on this forum swear by Variacs. A simple and likely dumb question. Would the Variac plug into the GFCI, or would you put the GFCI(s) on the output side?
Well, think about it this way: Whatever you plug into the GFCI will be protected by the GFCI. If you want to also protect your variac then plug your variac into the GFCI.
Peter W.- Posts : 1351
Join date : 2016-08-07
Location : Melrose Park, PA
deepee99 wrote:Thanks. The reason I asked was I had a variac that developed a ground fault all on its own...corndog71 wrote:deepee99 wrote:A lot of people on this forum swear by Variacs. A simple and likely dumb question. Would the Variac plug into the GFCI, or would you put the GFCI(s) on the output side?
Well, think about it this way: Whatever you plug into the GFCI will be protected by the GFCI. If you want to also protect your variac then plug your variac into the GFCI.
Variacs are Variable Autotransformers - meaning that they are NOT isolation transformers - there is only one (1) winding, with a variable take-off to control voltage. Those who expect them to behave as a standard transformer could be unhappily surprised. And, if tested as a standard dual-or-more-winding transformer, they will display faults right down the line.
http://www.electronics-tutorials.ws/transformer/trans33.gif?x98918 Variac Schematic.
Multi-winding multi-tap transformer: http://www.learnabout-electronics.org/ac_theory/images/Power-txfmr-shematic.gif Note that there is no connection between the primary and the secondary.
NOTE: Unless you have a metered variac - volts and amps - it is, really, not very useful, and in fact can be genuinely dangerous.
Similar topics
