ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals

Topic Options
Rate This Topic
#18417 - 12/09/02 07:41 PM Transfer switch feeder
sparkync Offline
Member
Registered: 10/17/02
Posts: 809
Loc: NC
I think I'm missing something..must be because I'm tired tonight... If I have a 8000 wt. generator and using 120 volts circuits it can handle 66.6 amps, and on 240 volts it can handle 33.3 amps, should not the feeder and main breaker be rated at 66.6 amps..at the maximum capacity?? I think I might be missing something here.. awfully tired I feel like this is probably a dumb question, but just can't get my head to work right, right now Is the sizing different on generators?? Thanks....Steve
Top
Work Gear for Electricians and the Trades
#18418 - 12/09/02 10:21 PM Re: Transfer switch feeder
Trumpy Offline


Member
Registered: 07/05/02
Posts: 8211
Loc: SI,New Zealand
Steve,
Sit down with a coffee, do your calc's again,
I am sure that you have missed something.
Have you figured Power Factor(Cos Phi), in to your calcs?.
How about losses?.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin
Top
#18419 - 12/10/02 05:33 AM Re: Transfer switch feeder
jdevlin Offline
Member
Registered: 08/07/02
Posts: 402
Loc: welland ontario canada
Think double pole. 33.3 x 2 =66.6
Top
#18420 - 12/10/02 01:00 PM Re: Transfer switch feeder
pauluk Offline
Member
Registered: 08/11/01
Posts: 7520
Loc: Norfolk, England
Assuming that the generator's 120V output is split across each half of the 240V winding, then loading 4000 watts on each leg (ignoring power factor concerns) would result in 33.3A on each side of the breaker. The neutral in this case would carry no current, just as if the supply were from a xfmr.
Top

Member Spotlight
Member Since: 04/03/02
Posts: 6776
New in the Gallery:
SE cable question
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box


Who's Online
1 registered (sparkyinak), 44 Guests and 9 Spiders online.
Key: Admin, Global Mod, Mod
 
New in the Gallery:
SE cable question
 
Top Posters (30 Days)
Admin 51
HotLine1 43
gfretwell 17
Trumpy 16
Ruben Rocha 13
 
Newest Members
clee512, Jdscott2005, FAIZAN, Regitest2, sureshazhagai

ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals