800 A service
- Thread starter AndyA
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Why did you run the conduit before you checked the wire size? That is risky
Your choices are 4 parallel sets of 300 kcm with 2 sets in each conduit which will give you a total of 736 amps. So if the calculated load is 736 or less you could connect to an 800 amp breaker.
For a full 800 amp service you need 4 parallel runs (2 in each conduit) of 350 kcm
I didn't check to see if they would fit but it seems it will.
Edit...
I made some error in my math but I can't even duplicate it so I must have typed in the incorrect number... Infinity has the correct answer below.
Your choices are 4 parallel sets of 300 kcm with 2 sets in each conduit which will give you a total of 736 amps. So if the calculated load is 736 or less you could connect to an 800 amp breaker.
For a full 800 amp service you need 4 parallel runs (2 in each conduit) of 350 kcm
I didn't check to see if they would fit but it seems it will.
Edit...
I made some error in my math but I can't even duplicate it so I must have typed in the incorrect number... Infinity has the correct answer below.
Last edited:
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I get 4 sets of 300 kcmil Al in two raceways for the full 800 amps. 260*2*80%*2=832 amps. Raceway fill isn't an issue.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
600 kcmil Al= 340 amps*2= 680 amps, no good next size up is 700 amps. Those conductors are too small for 800 amps.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Is that a high-leg delta? (Neutral and high leg could be smaller)
Metal or PVC conduit? (Metal could be EGC)
Service or feeder? (Will there be an EGC?)
My calc shows that eight 400s will fit in a 4" PVC conduit.
I think my best bet is to run 500MCM copper
no High leg. Running 4” PVC
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Hope you already have the gear, I’m looking at almost 10 months lead time for an 800 amp fusible 600 volt disconnect, and an 800 amp 277/480 three phase MB panelboard. Found two new 800 amp disconnects at a salvage place in Wisconsin, so instead of a 800 amp panelboard, I’m doing a wireway with off the shelf disconnects. Got to have the engineer re-draw it for the inspector.
Yes I have everything ready and mounted. Had to shop all over on line to collect it all.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
That will work. 380*2=760 next size up rule 800 amps. You could also use two sets of 750 aluminum. 385*2=770 amps.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
Just curious, why do you think 500 copper is better? I would much prefer the smaller aluminum personally. Can your equipment handle for sets per phase?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
I would probably reduce the neutral a couple sizes too
Why isn't this engineer specifying the conductors?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Good question. And if he wants the full 800 amps then the installer will have to provide it. Since he already install the equipment he might be limited as to the wire size and how many sets he can actually use.
If he specked 500 CU that is what he wants. If he does allow you to go with AL he'll probably be wanting a credit for the customer.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
The gear will probably only have double lugs, triple is special order. My engineer specs three sets of 300 kcmil AL. I probably need to go back and have him change it to two sets of 750. I haven’t ran any pipe yet because it took so long to get the prints.
- Status