200 Amp residential service

[goldstar]

What I thought should have been a simple answer to a simple question turned out to have multiple answers from some of my EC colleagues of whom I asked several questions.

I'm repairing/replacing an existing 200A service on a residence. The service comes down the side of the house on the driveway side. The existing service had to be temporarily re-suspended using SEU cable due to a hardy-plank siding installation. The existing service had been run in 2" PVC with (3) 2/0 copper conductors. I want to install new 2" PVC and I'll be using a 90 and a PVC LB on the load side of the meter enclosure and into the existing MBP. The MBP is not being changed. FYI, NJ is still on the 2014 NEC

Here were my questions :

1. Can I use 2/0 copper THHN for the service ? (Most of my colleagues say no they always use 3/0 for all conductors)
2. Can I down-size the neutral 2 sizes to # 1? (most of my colleagues say no)
3. Can I use an LB on the load side of the meter where it enters the house ?
4. Do I have to use sch. 80 on the load side of the meter where it enters the house ? (Remember it's on the driveway side and can be hit by a car if the HO comes home drunk )
5. Is an LB rated for use with sch. 80 PVC ?

Some of my colleagues suggested that I use aluminum. That would mean I'd have to go to 4/0. My reason for wanting to use #2/0 copper is so it will fit easier inside the LB.

One of my colleagues also suggested I look at section 310.15 (B)(7)(1) thru (4)

310.15 Ampacities for Conductors Rated 0–2000 Volts.
(B) Tables.
(7) 120/240-Volt, Single-Phase Dwelling Services and Feeders.
For one-family dwellings and the individual dwelling units of two-family and multifamily dwellings, service and feeder conductors supplied by a single-phase, 120/240-volt system shall be permitted be sized in accordance with 310.15(B)(7)(1) through (4).
(1) For a service rated 100 through 400 A, the service conductors supplying the entire load associated with a one-family dwelling, or the service conductors supplying the entire load associated with an individual dwelling unit in a two-family or multifamily dwelling, shall be permitted to have an ampacity not less than 83 percent of the service rating.
(2) For a feeder rated 100 through 400 A, the feeder conductors supplying the entire load associated with a onefamily dwelling, or the feeder conductors supplying the entire load associated with an individual dwelling, unit in a two-family or multifamily dwelling, shall be permitted to have an ampacity not less than 83 percent of the feeder rating.
(3) In no case shall a feeder for an individual dwelling unit be required to have an ampacity greater than that specified in 310.15(B)(7)(1) or (2).
(4) Grounded conductors shall be permitted to be sized smaller than the ungrounded conductors, provided that the requirements of 220.61 and 230.42 for service conductors or the requirements of 215.2 and 220.61 for feeder conductors are met.

So, in reading this I see that if I have a service rated at 200A, 83% of that would be 166A wire rating. Can I then use 2/0 wire rated at 175A ? Can I also drop the neutral down to # 1 ?

Thanks

 

[Leespark57]

Yes, 2/0 CU or 4/0 AL is ok. No need for schedule 80, which would do you no good if a car hit it anyway. You will want to install a bollard of some type in the driveway in case my wife ever tries to park there. Personally I would run 4/0 AL (full size) in 2".

 

[infinity]

If using PVC then Sch80 is required where the raceway is subject to physical damage which IMO includes in a driveway. If you're using an LB check the maximum conductor size that is stamped inside of the LB, it is often smaller than what is permitted in the raceway.

 

[DBoone]

2/0 - 2/0 - 2 copper is common here

 

[goldstar]

2/0 - 2/0 - 2 copper is common here

Thanks. I thought you could only drop the neutral down 2 trade sizes.

 

[goldstar]

If using PVC then Sch80 is required where the raceway is subject to physical damage which IMO includes in a driveway. If you're using an LB check the maximum conductor size that is stamped inside of the LB, it is often smaller than what is permitted in the raceway.

I have stripped the sheath off SEU cable and installed the (2) 4/0's and the bare 2/0 in PVC to the MBP before but that's a bear. I was trying to avoid that. Do you happen to know what the cu in of a 2" LB is off hand ?

 

[goldstar]

Yes, 2/0 CU or 4/0 AL is ok. No need for schedule 80, which would do you no good if a car hit it anyway. You will want to install a bollard of some type in the driveway in case my wife ever tries to park there. Personally I would run 4/0 AL (full size) in 2".

I contacted several EI's. Some require the sch. 80 and some don't. For the few extra $$ I'll put in the sch 80 on the load side of the meter. Thanks for your reply.

 

[tortuga]

I have stripped the sheath off SEU cable and installed the (2) 4/0's and the bare 2/0 in PVC to the MBP before but that's a bear. I was trying to avoid that. Do you happen to know what the cu in of a 2" LB is off hand ?

Conduit bodies are mostly all sized based on a prescriptive listing which gives a maximum of 3 XHHW conductors. The conductor size depends on the conduit trade size. (Table 40 on page 121 of UL 514B)
So a 2" LB would be three 3/0 XHHW or 0.2642 IN your max fill then would be 0.7926 IN
Cheers

 

[ramsy]

I have stripped the sheath off SEU cable and installed the (2) 4/0's and the bare 2/0 in PVC..

Does that void the SEU listing for outdoor wet locations in raceway?

 

[goldstar]

Conduit bodies are mostly all sized based on a prescriptive listing which gives a maximum of 3 XHHW conductors. The conductor size depends on the conduit trade size. (Table 40 on page 121 of UL 514B)
So a 2" LB would be three 3/0 XHHW or 0.2642 IN your max fill then would be 0.7926 IN
Cheers

Thanks.:thumbsup:

 

[Dennis Alwon]

There is no rule that states you can drop the neutral 2 sizes. I have heard that for years but that is just an old wise tale.
You can actually drop the neutral as small as the grounding electrode conductor. However, you need to make sure the calculated load is small enough for the conductor used.

 

[goldstar]

Does that void the SEU listing for outdoor wet locations in raceway?

Sorry, let me explain a little better. On the load side of the meter, between the meter enclosure and the MBP, and if the PVC is continuous I have stripped off the sheath of 200A SEU cable and used the single conductors (4/0, 4/0 and bare 2/0) and never had a problem. The 4/0's are XHHW and are marked. I have had cases where running PVC continuous between the meter enclosure and the MBP was not practical so I've stubbed a piece of 2" PVC out of the back of a 2" LB into the house just above the sill plate, I then installed a length of SEU cable with a 2" squeeze connector on the end (and enough of the single conductors to get to the meter enclosure), threaded it onto the end of a female adapter and glued it onto the PVC stub. Again, never had a problem.

 

[goldstar]

There is no rule that states you can drop the neutral 2 sizes. I have heard that for years but that is just an old wise tale.
You can actually drop the neutral as small as the grounding electrode conductor. However, you need to make sure the calculated load is small enough for the conductor used.

Dennis, I checked with an EI (who is also one of our CEU instructors and on the licensing board for the State) and he advised me that on a single family residence the norm is to drop down 2 sizes on a service.(at least that's here in NJ). If you look at SEU cable that's the way it's constructed. Shouldn't make any difference if you're using single CU or AL conductors.

I started this thread because I generally use SEU cable and haven't installed a 200A service using PVC and single conductors in a long time. I wanted to check with some of my colleagues on wire sizes before placing an order. I was surprised to find out how many didn't know about 310.15(B)(7) and down-sizing the wire. After hearing their answers I started thinking "Maybe there was something I missed".

 

[romex jockey]

On the driveway physical protection , why can't a few pillars be installed for 'vehicular' safety?

~RJ~

 

[goldstar]

On the driveway physical protection , why can't a few pillars be installed for 'vehicular' safety?

~RJ~

I suppose you could do that but if you're married ask your wife is she wouldn't mind having 2 concrete bollards installed for protection

 

[romex jockey]

LOL, you got me there Goldone..... ~RJ~

 

[Dennis Alwon]

Dennis, I checked with an EI (who is also one of our CEU instructors and on the licensing board for the State) and he advised me that on a single family residence the norm is to drop down 2 sizes on a service.(at least that's here in NJ). If you look at SEU cable that's the way it's constructed. Shouldn't make any difference if you're using single CU or AL conductors.

I started this thread because I generally use SEU cable and haven't installed a 200A service using PVC and single conductors in a long time. I wanted to check with some of my colleagues on wire sizes before placing an order. I was surprised to find out how many didn't know about 310.15(B)(7) and down-sizing the wire. After hearing their answers I started thinking "Maybe there was something I missed".

My point is that the code doesn't state that you drop 2 sizes. That may be the norm but it can be misleading.
Go to Southwire.com and see that they also make 4/0, 4/0, 4/0 seu cable

 

[infinity]

I have had cases where running PVC continuous between the meter enclosure and the MBP was not practical so I've stubbed a piece of 2" PVC out of the back of a 2" LB into the house just above the sill plate, I then installed a length of SEU cable with a 2" squeeze connector on the end (and enough of the single conductors to get to the meter enclosure), threaded it onto the end of a female adapter and glued it onto the PVC stub. Again, never had a problem.

The problem with installing SEU in an LB is that you cannot maintain the required minimum 5X bending radius of the cable. To comply with the 5X requirement you have to use an elbow instead.

My point is that the code doesn't state that you drop 2 sizes. That may be the norm but it can be misleading.

Go to Southwire.com and see that they also make 4/0, 4/0, 4/0 seu cable

I agree, but I seem to remember hearing about the two size reduction too.

 

[goldstar]

The problem with installing SEU in an LB is that you cannot maintain the required minimum 5X bending radius of the cable. To comply with the 5X requirement you have to use an elbow instead.



I agree, but I seem to remember hearing about the two size reduction too.

I'm sure you're correct. The problem I have with using an elbow is that the hole you would have to cut in the siding would have to be oblong to accommodate the sweep. If I did that in this new Hardiplank siding the builder will go ape.

 

[infinity]

I'm sure you're correct. The problem I have with using an elbow is that the hole you would have to cut in the siding would have to be oblong to accommodate the sweep. If I did that in this new Hardiplank siding the builder will go ape.

I agree and admit that the LB is easier to install for that reason and looks better when finished. There is always a chance with the LB that an inspector could make you change it.