Generator install advice

[dwqman]

Hello all. I want to preface my question. My scope of work includes instrumentation, plc and motor controls. When my neighbor asked if I could help install his generator in his box truck, "maintenance van". I thought sure I can,It shouldnt be too complicated. I might have been wrong. I dont do this type of work every day and I am having trouble finding someone to give advice, hopefully you can help so this can be a safe install.

The generator is a 120V, 1 PH, 7.5kVA, with a max output of 62.5A.
It has a 2-pole 35A main circuit breaker and the neutral is bonded to the generator frame. It has a five connection output terminal block.
1 = L1 120v, 2= L2 120v, 3= neutral, 4= neutral, 5= ground.

This is where I get confused. The manual states " Because L1 and L2 from the genset are in phase, current in the Neutral conductors is the sum of the currents in L1 and L2. Wiring and equipment must be sized accordingly.

Question 1 - does the wire size of both individual neutral conductors from genset TB to panelboard have to be sized to carry 62.5A.

Question 2 - since the genset neutral is bonded to the genset frame and the genset frame is bonded to the vehicle frame do I have to apply a main bonding jumper between neutral and ground in the panelboard. Since the genset has a 2-pole 35A main he purchased a 6 space 100A main lug panelboard.

 

[steve66]

Hello all. I want to preface my question. My scope of work includes instrumentation, plc and motor controls. When my neighbor asked if I could help install his generator in his box truck, "maintenance van". I thought sure I can,It shouldnt be too complicated. I might have been wrong. I dont do this type of work every day and I am having trouble finding someone to give advice, hopefully you can help so this can be a safe install.

The generator is a 120V, 1 PH, 7.5kVA, with a max output of 62.5A.
It has a 2-pole 35A main circuit breaker and the neutral is bonded to the generator frame. It has a five connection output terminal block.
1 = L1 120v, 2= L2 120v, 3= neutral, 4= neutral, 5= ground.

This is where I get confused. The manual states " Because L1 and L2 from the genset are in phase, current in the Neutral conductors is the sum of the currents in L1 and L2. Wiring and equipment must be sized accordingly.

Question 1 - does the wire size of both individual neutral conductors from genset TB to panelboard have to be sized to carry 62.5A.

Question 2 - since the genset neutral is bonded to the genset frame and the genset frame is bonded to the vehicle frame do I have to apply a main bonding jumper between neutral and ground in the panelboard. Since the genset has a 2-pole 35A main he purchased a 6 space 100A main lug panelboard.

What is this panel going to supply? Since the two outputs are in phase, it can't run any 240V or 208V loads. Only 120V loads. So I definately wouldn't be hooking it up to any existing panels in a building. (You would also have issues with any shared neutrals, and some grounding issues would need to be addressed.)

It looks like each output has a 31 amp capacity. That fits with the 35A breaker rating. Then the total combined output is 62.5 amps. So for question #1, wouldn't you want to use a single neutral wire sized for 63 amps?

Question #2: No, you want the netural and ground bonded in one and only one place. I would suggest making sure the neutral is bonded at the generator.