chadwi
New User
- Location
- Oshkosh WI
- Occupation
- Trailer builder
Hello thank you for having this forum. I consider myself a decent handyman but I'm still on the fence on a hookup for a build I'm doing.
Here are the basics:
Project is a mobile food truck
"sorry I know this topic is prob beat to death"
Truck is running 120v only appliances.
I'm using gfci breakers not outlets in panel.
3 pole double throw manual transfer switch.
Older onan emerald 3 genset "6500watt"
Questions are as follows.
1) there are 4 wires coming from genset. 2 black hots, 2 whites, 1 ground. It has a 30 amp brkr and a 20amp brkr even tho both hots are the same gauge wire. Since this generator will only power 120v outlets I read in the manual I can simply tie the 2 hots together and 2 neutrals together so it draws power equally I assume from both windings? It also said I can change the 20amp brkr to a 30amp if I wire it this way. I'd have to up the wire gauge obviously from generator to switch and from switch to panel but does this sound correct? I've read differing opinions on tying hots versus bringing 2 legs up and also opinions on not tying neutrals together "unsure why in this case".
2. Since this is an older unit am I correct in assuming the genset is neutral/ground bonded already? Factory as is out of a motorhome. All I see is the large copper ground strap from generator to the case and which in turn will be through truck frame.
3. Regardless if I tie hots vs 2 legs or tie neutrals at the generator BEFORE running into transfer switch and out to the panel how do I hook up the neutral/ground in the transfer switch? The panel is good to go "unbonded neutral bar" and will rely on the shore powers correctly wired feed panel.
Ive heard so many differing opinions on this... especially with using gfci brkrs/outlets. Which I do understand that gfci reads neutral and hot and any drop trips it and I know if using gfci there can be no neutral/ground bond anywhere in the system... so how does gfci work if the gen is neutral bonded internally? Especially if tying ground and neutral together at the transfer switch as so many others have suggested. Others have said leave the generator ground off in the switch and others have said leave the neutrals off in the switch "effectively saying don't even run them-which sounds bad/dumb to me" am I missing something here? It's almost like reading a no win. I don't want patrons touching truck and getting 20amps running through them when on gen power.
I do fully understand the shore power hookup and have that down pat. It's this generator into transfer switch ground and neutral wire hookup location I'm dealing with.
The transfer switch does not have a ground bar or neutral bar "I know I can buy them but do I need them?"
The shore power to transfer switch I assume would be the 2 hot legs going to 1 each of the terminals "220v with each side of panel getting 120v" and the neutral using the third terminal "switch neutral when using the switch", and the main panel aswell as the truck in multiple places is already grounded "shorepower outlet is already grounded to panel and truck" Or do I need to make sure to carry ground out through the transfer switch also instead of grounds being tied at the switch and panel for any reason? That being said since I ONLY need 120 but most shore power at 50amp is split can I also tie the 2 hots together at the switch "2 hots on 1 transfer switch lug" and run that into the main panel so I get even distribution of the available amps or am I over thinking this and it will then be 220v on both sides of the main panel lol? I have an uneven amp distribution in the main panel is what I'm trying to get at... All under 50 amp but one side is going to want to draw 30amps no matter how I switch due to how customer wants certain things to run. Hence my wanting to tie generator hots together to hopefully get the full amp draw over to either side of the panel that wants it. "Think as this way. Both sides of panel are distributed evenly at about 20amps of use on each side at same time continuously including overage for compressor kick ins etc... however each side also has an intermittent large amp draw appliance on it that when needed will draw an additional up to 10-12amps. One has a large a.c. unit the other has an electric water heater." Customer knows he can't have full use of everything on the truck and both of those large amp draw appliances at the same time but I gotta give him at least one lol... And I don't want to have him switching breakers in panel to use either one so that's why I want 30 amps available to each side of the panel and why switching the gen 20 amp brkr out for a 30amp and tying both leads before the switch makes sense. But how to do it on shorepower? Cuz bringing 50amp in over 2 120v legs means a max of 25amps is only available to each side of the panel instead of 30amps.
Thanks guys hopefully someone has some more insight for me
Here are the basics:
Project is a mobile food truck
"sorry I know this topic is prob beat to death"
Truck is running 120v only appliances.
I'm using gfci breakers not outlets in panel.
3 pole double throw manual transfer switch.
Older onan emerald 3 genset "6500watt"
Questions are as follows.
1) there are 4 wires coming from genset. 2 black hots, 2 whites, 1 ground. It has a 30 amp brkr and a 20amp brkr even tho both hots are the same gauge wire. Since this generator will only power 120v outlets I read in the manual I can simply tie the 2 hots together and 2 neutrals together so it draws power equally I assume from both windings? It also said I can change the 20amp brkr to a 30amp if I wire it this way. I'd have to up the wire gauge obviously from generator to switch and from switch to panel but does this sound correct? I've read differing opinions on tying hots versus bringing 2 legs up and also opinions on not tying neutrals together "unsure why in this case".
2. Since this is an older unit am I correct in assuming the genset is neutral/ground bonded already? Factory as is out of a motorhome. All I see is the large copper ground strap from generator to the case and which in turn will be through truck frame.
3. Regardless if I tie hots vs 2 legs or tie neutrals at the generator BEFORE running into transfer switch and out to the panel how do I hook up the neutral/ground in the transfer switch? The panel is good to go "unbonded neutral bar" and will rely on the shore powers correctly wired feed panel.
Ive heard so many differing opinions on this... especially with using gfci brkrs/outlets. Which I do understand that gfci reads neutral and hot and any drop trips it and I know if using gfci there can be no neutral/ground bond anywhere in the system... so how does gfci work if the gen is neutral bonded internally? Especially if tying ground and neutral together at the transfer switch as so many others have suggested. Others have said leave the generator ground off in the switch and others have said leave the neutrals off in the switch "effectively saying don't even run them-which sounds bad/dumb to me" am I missing something here? It's almost like reading a no win. I don't want patrons touching truck and getting 20amps running through them when on gen power.
I do fully understand the shore power hookup and have that down pat. It's this generator into transfer switch ground and neutral wire hookup location I'm dealing with.
The transfer switch does not have a ground bar or neutral bar "I know I can buy them but do I need them?"
The shore power to transfer switch I assume would be the 2 hot legs going to 1 each of the terminals "220v with each side of panel getting 120v" and the neutral using the third terminal "switch neutral when using the switch", and the main panel aswell as the truck in multiple places is already grounded "shorepower outlet is already grounded to panel and truck" Or do I need to make sure to carry ground out through the transfer switch also instead of grounds being tied at the switch and panel for any reason? That being said since I ONLY need 120 but most shore power at 50amp is split can I also tie the 2 hots together at the switch "2 hots on 1 transfer switch lug" and run that into the main panel so I get even distribution of the available amps or am I over thinking this and it will then be 220v on both sides of the main panel lol? I have an uneven amp distribution in the main panel is what I'm trying to get at... All under 50 amp but one side is going to want to draw 30amps no matter how I switch due to how customer wants certain things to run. Hence my wanting to tie generator hots together to hopefully get the full amp draw over to either side of the panel that wants it. "Think as this way. Both sides of panel are distributed evenly at about 20amps of use on each side at same time continuously including overage for compressor kick ins etc... however each side also has an intermittent large amp draw appliance on it that when needed will draw an additional up to 10-12amps. One has a large a.c. unit the other has an electric water heater." Customer knows he can't have full use of everything on the truck and both of those large amp draw appliances at the same time but I gotta give him at least one lol... And I don't want to have him switching breakers in panel to use either one so that's why I want 30 amps available to each side of the panel and why switching the gen 20 amp brkr out for a 30amp and tying both leads before the switch makes sense. But how to do it on shorepower? Cuz bringing 50amp in over 2 120v legs means a max of 25amps is only available to each side of the panel instead of 30amps.
Thanks guys hopefully someone has some more insight for me
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