Splicing oversized wires due to voltage drop
- Thread starter arnettda
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Sierrasparky
Senior Member
- Location
- USA
- Occupation
- Electrician ,contractor
you can splice a smaller wire at the point just before the breaker.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Just curious, does the DB cable have an overiszed EGC?
Sierrasparky
Senior Member
- Location
- USA
- Occupation
- Electrician ,contractor
Just had to throw that one on the fire
Now that you jogged my memory It needs to be? It also needs to be when you parallel conductors?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Could be, take a look at 250.122(B).
ptonsparky
Tom
- Occupation
- EC - retired
Outside direct bury. Where is the 100 amp breaker? Line, load, or both? Answer the questions correctly and forget the larger EG proplem.
By reading 250.122 I would have to say yes. There seems to be a other opinions though?
- Occupation
- Licensed Electrician
ptonsparky made a good point. It all depends on where the first 100A breaker is, i.e. you can put 4/0AL on a 200A breaker and run it ten feet on up to ten miles or more and not have to use a larger EGC. Put the same wire under a 100A breaker or less and you need to upsize the EGC.
Make sense? Of course not.
What's important is- Why did you upsize to 4/0? What is the connected load? If you need 100A at a great distance from the source then voltage drop is a real concern and the EGC should be upsized.
- Location
- Massachusetts
It is only with 15, 20 & 30 amp circuits that 250.122(B) causes real heartache.
Once you get above those sizes things make much more sense.
Once you get above those sizes things make much more sense.
60 amp load 560 feet away.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
It gets better but doesn't go away. Take a 40 amp circuit and increase conductors and you are supposed to increase EGC by same proportion, yet if same ungrounded conductors were part of a 60 amp circuit the EGC could easily be smaller than what may required by the 40 amp circuit.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Bringing a 4/0 conductor into a space intended for 60 or 100 amp conductors may have wire bending space issues and the reduction may still need be done in a separate enclosure.
- Location
- Massachusetts
Did I say it went away?
Do you think I am unaware of the rules?
It just seems every time you quote me it is to correct me over things I did not say
ptonsparky
Tom
- Occupation
- EC - retired
Arnettda:
Making assumptions.
A 60 amp load would use #4 al. A 100 amp CB would require a #6 al for an EG. Increasing the size of your phase conductors to 4/0 al would require a proportinal increase in size for the EG resulting in a 2/0 Al. 4/0-4/0-2/0 is a typical cable configuration that we bury.
4/0 AL could be protectecd by a 200 Amp CB and only require a #4 AL EG. Table 250.122
4/0 AL SE conductors, #2 Al. Table 250.66
Making assumptions.
A 60 amp load would use #4 al. A 100 amp CB would require a #6 al for an EG. Increasing the size of your phase conductors to 4/0 al would require a proportinal increase in size for the EG resulting in a 2/0 Al. 4/0-4/0-2/0 is a typical cable configuration that we bury.
4/0 AL could be protectecd by a 200 Amp CB and only require a #4 AL EG. Table 250.122
4/0 AL SE conductors, #2 Al. Table 250.66
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kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Did it ever occur to you that maybe I was just adding my own $.02 and was talking to the entire forum and not just you?
Sorry for peeing in your Cheerios.
- Location
- Massachusetts
Well you quoted me so I tend to take it as aimed at me. I don't think that is odd.
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