I have a small project installing a connex box with the following installed inside. A 3 phase 480 volt panelboard, a small transformer for a sub panel 240/120. and some misc motors and compressors. My question is that the connex will be fed from a generator installed next to the connex, all of which will be use for about a year. What are the grounding requirements and the requirments for bonding the generator grounded conductor. Since this connex will be fed from the generator there will be a provided 3 phase 5 wire pin and sleeve male connector from the main panelboard for plug in to the generator.
Out building generator feed.
- Thread starter TDevries
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- Lockport, IL
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- Semi-Retired Electrical Engineer
What is a connex?
A storage container, like the ones used on cargo ships.
If you have seen those Pods containers you can rent from I think Home Depot, that is like a connex only smaller. They use them a lot in Iraq/Afghanistan.
You would bond at the 240/120 transformer and at the disconnect that the transformer feeds into. I assume the generator is 480 v Delta, so there is no grounded conductor. Need to know the gen voltage rating.
Please correct to me if I am wrong, I was up late with a crying baby.
Starting with the generator supplying power to the building we need to know if it's a portable unit or permanetly installed and if it has a breaker. If its a portable unit and the power feed is hard wired from the gen set, a grounding electrode system is required at the generator. (250.34(B).If there is a pin and sleeve on the gen set, no electrode required.
At the connex 250.32(B) requires a grounding electrode system be installed. If a rod is used, an additional rod is required. If a ring is used at least 20' is required and also requires encircling the connex 30" deep.
Since this is a stand alone power supply, it is considered a seperately derived system and requires the neutral to be grounded. If there is a breaker on the unit the system bonding jumper gets installed on the gen set. If not, the jumper goes at the first OCPD. If on the unit, the neutral and grounds seperate past the system bonding jumper going into the connex. The grounding electrode system gets connected to the equipment ground with the supply feed to the building. Hope that answered it.
At the connex 250.32(B) requires a grounding electrode system be installed. If a rod is used, an additional rod is required. If a ring is used at least 20' is required and also requires encircling the connex 30" deep.
Since this is a stand alone power supply, it is considered a seperately derived system and requires the neutral to be grounded. If there is a breaker on the unit the system bonding jumper gets installed on the gen set. If not, the jumper goes at the first OCPD. If on the unit, the neutral and grounds seperate past the system bonding jumper going into the connex. The grounding electrode system gets connected to the equipment ground with the supply feed to the building. Hope that answered it.
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