250.92 bonding of services
- Thread starter Dexie123
- Start date
- Status
- Occupation
- Licensed Electrician
No to 250.92, but 250.97 may come into play.
Dang you old man! You beat me to it.
Dang you old man! You beat me to it.
Last edited:
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I agree, if the voltage is over 250 volt to ground, like in a typical 480-208/120 volt transformer then the 480 volt circuit would require a bonding bushing if there were concentric or eccentric KO's. If all KO's are full size for the raceway entry then no bonding bushings are required. I see transformers every day with FMC entries and bonding bushings which is just a waste of someone's money.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
IMO, yes the separately derived system should follow the bonding requirements of 250.92 assuming the voltage is less than 250 to ground
- Location
- Massachusetts
A supply-side [equipment] bonding jumper is required for a separately derived system. There is no equivalent requirement for services.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
No I realized that was for services but I see a separately derived system as a service (in a sense) That's why I stated IMO. I could not find a code that directly linked a sep. derived system but it seems that it should follow 250.92.
If a separately derived system is not considered a service then 250.92 applies. Why does every sep. derived trany need connection to the gec? Seems to IMPLY what I am thinking.
Looks like a lion BUT it's a dog,
Looks like a service but it's not
At first thought it would seem the Code would add ther 250.92 requirements to SDSs but as Smart$ notes with an SDS we have a supply side bonding jumper and if the primary is over 250 vtg 250.97 bonding is required.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I agree, I hear it all the time treat the transformer like a service but not all of the requirements are the same.
- Location
- Massachusetts
I agree in many ways they are similar.
But 250.92 specifically says services and article 100 tells us a service can only come from a utility.
That said, I like Gus's way of putting it.
- Occupation
- Licensed Electrician
I'll be honest, I put a bond bushing on the raceway for the secondary at the tranny. I know I don't have to, it's just the way I was taught. That probably had to do with the fact that the guy who taught me always bonded the neutral at the first disconnect, "It's just like a service", he would say. I keep the tradition going in his honour.
I have done many remodels on stores and seen bond bushing on both ends of the conduit with a continuous jumper from the case of the tranny and to the panel and on over to a EGC buss. I'm glad I didn't learn that.
I have done many remodels on stores and seen bond bushing on both ends of the conduit with a continuous jumper from the case of the tranny and to the panel and on over to a EGC buss. I'm glad I didn't learn that.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
The response we got in Raleigh from the cmp member is this..
Yes 250.90 and 250.96 were the references. This is sort of all encompassing but that was the response.
Yes 250.90 and 250.96 were the references. This is sort of all encompassing but that was the response.
- Status