Home |
Search |
Today's Posts |
|
Home Repair (alt.home.repair) For all homeowners and DIYers with many experienced tradesmen. Solve your toughest home fix-it problems. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
Posted to alt.home.repair
|
|||
|
|||
Voltage drop
I have heard in the trade as a general rule if you are using #12 wire
for a 20A circuit you should go to #10 if the run is over 100 ft. The fan #14 or #12 thread prompted me to just do a quick check at one of the voltage drop web pages. http://www.csgnetwork.com/voltagedropcalc.html If you use this web page and try using 16A which would be the max on a 20A circuit you get 5% voltage drop in just the branch circuit. |
#2
Posted to alt.home.repair
|
|||
|
|||
Voltage drop
In article , Terry wrote:
If you use this web page and try using 16A which would be the max on a 20A circuit you get 5% voltage drop in just the branch circuit. The maximum load on a 20A circuit is... any guesses? ...wait for it... 20A. 16A is the maximum *continuous* load on a 20A circuit. -- Regards, Doug Miller (alphageek at milmac dot com) It's time to throw all their damned tea in the harbor again. |
#3
Posted to alt.home.repair
|
|||
|
|||
Voltage drop
Terry wrote: I have heard in the trade as a general rule if you are using #12 wire for a 20A circuit you should go to #10 if the run is over 100 ft. The fan #14 or #12 thread prompted me to just do a quick check at one of the voltage drop web pages. http://www.csgnetwork.com/voltagedropcalc.html If you use this web page and try using 16A which would be the max on a 20A circuit you get 5% voltage drop in just the branch circuit. My copy of NEC (1990 -- somewhat obsolete) only mentions voltage drop in FPN's (non-manditory notes). It recomends a max of 3% on branch circuits "at the farthest outlet of power, heating, or lighting loads", and a max of 5% on both feeder and branch circuit. 10ga copper is about 1.25 ohms / 1000', and 12ga copper is about 2 ohms / 1000', and 14ga copper is about 3.1 ohms / 1000' 3% of 120v is 3.6v. 100' of 12ga is actually 200' (hot & neutral) is .4 ohms so 3.6/.4 = 9 amps for 3% voltage drop at 100'. 10 ga. will give you 14.4 amps at 100' and 14 ga. will give you 5.8 amps at 100'. Of course you may be willing to withstand greater voltage drops. (and yes, you get 5.33% voltage drop at 16A on 100' of #12: .4*16/120) |
#4
Posted to alt.home.repair
|
|||
|
|||
Voltage drop
On Jul 10, 8:25 pm, (Doug Miller) wrote:
The maximum load on a 20A circuit is... any guesses? ...wait for it... 20A. Just to be anal, the maximum load on a 20A circuit can be far greater than 20 amps, at least for a short period of time. According to the Trip Curves on the Square D web site, their QO series of breakers can handle a 2x load (or in this case, 40 amps) for just under 10 seconds before tripping. |
#5
Posted to alt.home.repair
|
|||
|
|||
Voltage drop
|
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Will my voltage drop? | Home Repair | |||
Low voltage lights - voltage drop/cable size | UK diy | |||
I need a reminder, what causes voltage drop.. | Electronics Repair | |||
Voltage Drop Under Load | Home Repair | |||
Voltage drop switching relays? | Electronics |