I was hoping to get some opinions on this. I have a situation where we have a prefab conex box that comes with a bunch of equipment in it. I provided a 100 amp, 240/120 volt single phase service to it. The service disconnect is a fused, doublethrow switch with center off position. The double throw switch is essential a manual transfer switch so that we could mount a portable generator connection plug on the outside of the conex box. I ran #3’s rated for 100amps out to the plug. The project is essential done and we were just provided information on the portable generator that they have on site and will be using to power this conex box should they need to. Its name plate says it’s a 54KVA genset and has selectable outputs at 480 volts as well as at 240and 208. The 240 and 208 volt connection points have a circuit breaker rated for 175 amps. I have been asked to size the conductors for a whip/generator cord that they can keep in the conex box so that when needed they can pull it out and connect the generator to the plug. The question is what size does this whip need to be. Do I size the whip at 115% of the nameplate current rating of the generator per 445.13. If I do this, it would obviously be larger than the conductors that are already inplace from the generator plug to the double throw fused switch(maybe 5 feet long) so would these conductors need to be bumped up to? Or do I size the whip to the generator breaker and again would the conductors from the plug to the switch need to be upsized? Or because this is a temporary installation and outside can I just size the whip based on the 100 amp service already in place?
Generator Whip Conductor Size
- Thread starter BHGBHG
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qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
If it is a fused (100 amp) manual transfer switch I would size the cord at 100 amps. Keeping in mind that sometimes multi conductor cable ampacity is different than individual conductors.
david
Senior Member
- Location
- Pennsylvania
you stated the first over current device was a gen. breaker 175 amps (115 % conductors)
i would provide 100 amp over current protection for the conductors supplying the feed to the 100 amp panel
or change the conductors to a min of 175 amps
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ceb58
Senior Member
- Location
- Raeford, NC
245.13 (A) states that if you DO NOT have overcurrent protection then 115%. You have overcurrent protection by the breaker on the generator so you must go with 245.13 (B)
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
ceb58
Senior Member
- Location
- Raeford, NC
Do you mean 445?
Yes, backwards fingers:rant:
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