3/4" Conduit body with 4 #8 AWG

[SKSolar]

Based on conduit fill calculation, 3/4" conduit would be able to take 4 #8 AWG wires (L1, L2, N, G) and two pairs of CT wires. As need to use a conduit body to connect to an Eaton AC Disconnect Box and also to the Main Service Panel. Do you think I can get those wires through via a 3/4" conduit body easily at 90 degree?

 

[LarryFine]

I would think it would be fine unless your CT wires are #10s.

 

[infinity]

You're allowed (6)-#8's in a 3/4" EMT so as long as you 2 pair CT wires are no larger than a single #8 you're good. As far as the conduit body if you stay within the fill for the raceway with the size of your conductors there should be no issue.

 

[LarryFine]

Raceway Fill Calculator

 

[SKSolar]

I also bought a fuse able Eaton DG222NRB Disconnect Box from PV to MSP. The N terminals has 3 slots/nuts connections (1,2, 3 as shown on the picture. Dos that means I need to connect to the 3 slots? Can I just cut the wires and make connection to 1 & 3 ? I believe the other terminal is for Ground wire, correct? Why it did not use a Green Nut?

 

[LarryFine]

It's a neutral bus, not a grounding bus. You can use any terminal you wish.

The green screw in the cardboard is for bonding the cabinet to the neutral.

 

[jaggedben]

The 3/4 LB will be fine for that. (A 3/4 pulling elbow might not be, they often have a max below NEC fill allowance for the trade size.)

The disconnect is suitable for use as a service disconnect but I assume you're not going to use as one. (i.e. no line side tap). So it has provisions for bonding and grounding the neutral but you won't use those. To just use it as a disconnect you could:
- don't put a green screw to the box, and cut the neutral wire and land on the terminals
OR
- run the neutral straight through, install the green screw to the bar and use it as a *ground bar*
But not any screwy combination of those two. Keep ground and neutral separate.

 

[SKSolar]

The 3/4 LB will be fine for that. (A 3/4 pulling elbow might not be, they often have a max below NEC fill allowance for the trade size.)

The disconnect is suitable for use as a service disconnect but I assume you're not going to use as one. (i.e. no line side tap). So it has provisions for bonding and grounding the neutral but you won't use those. To just use it as a disconnect you could:
- don't put a green screw to the box, and cut the neutral wire and land on the terminals
OR
- run the neutral straight through, install the green screw to the bar and use it as a *ground bar*
But not any screwy combination of those two. Keep ground and neutral separate.

I am installing an Enphase PV system. The Disconnect is for disconnecting the AC current from Microinverter to the Backfeed breaker in Main Service Panel. The neutral has 3 terminal. You said I can run the neutral straight through 1, 2 and 3 terminal? That means I have to expose the wire in the neutral wire from 1 to 3?

 

[LarryFine]

You said I can run the neutral straight through 1, 2 and 3 terminal? That means I have to expose the wire in the neutral wire from 1 to 3?

No. You can run the neutral through the switch enclosure without stripping and terminating it at all.

Or, you can land the incoming neutral wire in one terminal, and the outgoing neutral wire in another.

In other words, neutral current would low through the neutral bus from one terminal to the other.

 

[jaggedben]

Why do you need a disconnect? The NEC doesn't require one. Utility requiring it? They don't require it to be fused do they?

Anyway if you had an unfused disconnect it would have no neutral bar and you'd pass the neutral right through.

 

[electrofelon]

. As far as the conduit body if you stay within the fill for the raceway with the size of your conductors there should be no issue.

Isn't the allowable conductors marked on a typical LB usually less than the raceway fill?

 

[SKSolar]

No. You can run the neutral through the switch enclosure without stripping and terminating it at all.

Or, you can land the incoming neutral wire in one terminal, and the outgoing neutral wire in another.

In other words, neutral current would low through the neutral bus from one terminal to the other.

Thanks Larry. Happy Thanksgiving Day to u & family.

 

[SKSolar]

Isn't the allowable conductors marked on a typical LB usually less than the raceway fill?

Yes Sir. Conductors area calculated is less than the allowable fill in this case. I am just wondering whether it can be pull through easily. Thank you.

 

[electrofelon]

Yes Sir. Conductors area calculated is less than the allowable fill in this case. I am just wondering whether it can be pull through easily. Thank you.

What I meant was that most LB's are marked with a number and size of conductors, and these markings are always less than the maximum allowable raceway fill. So you can have a conductor combination that has an allowable fill for the raceway but not for the LB. It's probably rarely enforced, but just be aware.

 

[SKSolar]

Why do you need a disconnect? The NEC doesn't require one. Utility requiring it? They don't require it to be fused do they?

Anyway if you had an unfused disconnect it would have no neutral bar and you'd pass the neutral right through.

Well, a Disconnect is required for a PV system in CA. The one I bought has two fuses for L1 & L2. There is a connection for N but it has 3 terminals as shown on the picture. I just wonder why it has 3. Maybe no no terminal would ok. The terminals only help to splice wires.

 

[jaggedben]

Isn't the allowable conductors marked on a typical LB usually less than the raceway fill?

For sizes up to 1", not so much.
For bigger sizes, much more so.

(As long as we're talking LBs and not pulling elbows.)

 

[jaggedben]

Well, a Disconnect is required for a PV system in CA.

No, it's not. But it is a very common utility requirement.

The one I bought has two fuses for L1 & L2. There is a connection for N but it has 3 terminals as shown on the picture. I just wonder why it has 3. Maybe no no terminal would ok. The terminals only help to splice wires.

The 3rd terminal would typically be for a grounding electrode conductor. Which you will not have.

 

[LarryFine]

Well, a Disconnect is required for a PV system in CA. The one I bought has two fuses for L1 & L2. There is a connection for N but it has 3 terminals as shown on the picture. I just wonder why it has 3. Maybe no no terminal would ok. The terminals only help to splice wires.

That's because it's a general-purpose switch, not one made just for your use. The three terminals are there for your convenience. There is no requirement to use them all.

For example, if used as a service disconnect, you would install the green screw to bond the enclosure, aand use the third terminal for a grounding electrode or the load EGC.

 

[infinity]

What I meant was that most LB's are marked with a number and size of conductors, and these markings are always less than the maximum allowable raceway fill. So you can have a conductor combination that has an allowable fill for the raceway but not for the LB. It's probably rarely enforced, but just be aware.

Good point due to the 6X rule but that only applies to conductors #4 and larger.

 

[don_resqcapt19]

Isn't the allowable conductors marked on a typical LB usually less than the raceway fill?

Only where the conductors are 4 AWG and larger. For 6 AWG and smaller the conduit body fill is the same as the trade size raceway that the conduit body is connected to. There may be a volume marked in the conduit body, but that only comes into play for splices and things like that using the rules in 314.16.