200 Amp residential service

[goldstar]

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.

Just an FYI, it was done that way originally and passed inspection. That doesn't necessarily make it right though. I don't know how it passed on the original installation based on how poorly it was installed. When I got to the job the first day the service was hanging on by a thread. The meter pan wasn't even attached to the house. The sheathing under the siding was dry-rotted. AND, that was only done 3 years ago.

 

[kwired]

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

~RJ~

The cost to do that justifies using RMC in the first place, though the bollards would protect more then just the raceway.

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".

NEC only says the neutral needs to be able to handle the load it will carry, but never can be smaller then the required grounding electrode conductor. There are jurisdictions that won't question the load as long as you don't go less then two sizes smaller then the ungrounded conductors.

 

[goldstar]

The cost to do that justifies using RMC in the first place, though the bollards would protect more then just the raceway.

Granted, but it's not going to protect me from my wife who wouldn't want an ugly bollard in the driveway. Houses in the area where this installation is are fairly close together. Taking up a foot or so of the driveway at the service location could present a problem for the HO.

 

[don_resqcapt19]

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

That was last in Note 3 in the "Notes to Ampacity Tables of 0 to 2000 Volts" in the 1993 code. The note was changed to eliminate the specific permission for the the neutral to be two sizes smaller in the 1996 code.

 

[don_resqcapt19]

The change was the result if a proposal submitted by Charlie Trout with the following substantiation:

SUBSTANTIATION: The NEC provides adequate requirements for the sizing of the grounded conductor. Note 3 correctly requires compliance with Sections 215-2, 220-22, and 230-42. The additional restriction of being permitted to be not more than two AWG sizes smaller than the ungrounded conductors has no relevance to grounded conductor sizing. Using Note 3 as presently written requires a larger grounded conductor than not using Note 3.

 

[goldstar]

Thanks for doing that research Don.

 

[newservice]

I've always found that 2 1/2" is better all around for the 200a entrances when negotiating turns and radius changes etc. My 2 cent.
Also I believe the POCO here which is National Grid, specs that it be in 2.5" conduit for a riser, I know this isnt a riser just sayin.

 

[Dennis Alwon]

I have never seen anyone run 2 1/2" conduit for a dwelling service. I have seen LB's increased in size for se cable.

 

[don_resqcapt19]

I've always found that 2 1/2" is better all around for the 200a entrances when negotiating turns and radius changes etc. My 2 cent.
Also I believe the POCO here which is National Grid, specs that it be in 2.5" conduit for a riser, I know this isnt a riser just sayin.

Utility riser conduit specs are typically based on the mechanical strength required to support their service drop.

 

[Dennis Alwon]

I always considered the riser as the conduit or cable from the meter to the point of attachment on the building. The mast was the conduit- 2"rmc around here, that went thru the roof and supported the service drop. 230.28 seems to support the mast statement.

 

[don_resqcapt19]

I always considered the riser as the conduit or cable from the meter to the point of attachment on the building. The mast was the conduit- 2"rmc around here, that went thru the roof and supported the service drop. 230.28 seems to support the mast statement.

Both utilities around me call it a riser, and the size is specified based on the size and length of their service drop conductors, but you are correct, the term should be mast.