Panel upgrade - confused about ground/neutral buss bars

[binovc]

I have an outdoor breaker cabinet (Zinsco) / meter socket combination. The indoor panel used to be a fuse box, but was converted to a breaker box. The wiring is as shown in the image. There is a breaker switch on the outdoor panel and also a main breaker on the indoor panel. (The outdoor panel has several other brekers not illustrated, that will eventually be relocated to the indoor panel). The only wires from the outdoor breaker panel to the indoor one are the two main legs and the newtral leg. The neutral is connected to the same bus bar that the ground is connected to (that goes to a ground rod). The indoor panel has the neutral and the ground bus bars connected with a bridge. My question, is this correct? Or should the neutral bar and ground bar be separated (by removing the bridge), and the neutrals all connected to the neutral bus bar, and the grounds all connected to the ground bus bar. If separated, should the ground bus bar be bonded to the cabinet with the bonding screw? And should the ground bus bar then be connected to --- where?
Later this year the existing service entrance will be re-located due to building an addition to the house. When relocated, the Zinsco panel will be discarded and there will be only a meter socket (no breakers). Local code does not require an outdoor disconnect - apparently the fire department simply removes the meter should a disconnection become necessary.
Thanks for the assist!

 

[pattenp]

With the way it is now the ground and neutral should be isolated in the main breaker box inside and the bridge be removed. A ground wire then needs to go from the main breaker panel box ground bar to the Neutral/Ground Bus Bar at the meter box. The meter box at this point should be the only place the neutral and grounds are bonded. Once the change is done with just having a meter socket then the neutrals and ground will be bonded in the main breaker panel with the bridge being replaced.

 

[binovc]

Ok, I will make the modifications to the new breaker panel and add the additional ground wire (as in the new image). What about adding the bonding screw to bond the ground bar to the cabinet?
Can you explain what the difference is between the two wiring jobs? Seems to me the grounds and neutrals all end up at the same place in both cases - right at the ground buss bar in the outdoor cabinet. The old fuse panel was wired as in the first image - probably because the code was different back then. I simply wired up the new breaker panel the same as the old fuse panel. The old fuse panel only had one neutral/ground buss bar.
Thanks.

 

[pattenp]

The new panel box does need to be bonded to the ground bar.

All I can say is code now allows the neutral and grounds to be bonded only at the first service point after the meter base. The combo meter/ breaker box is the first service point.

 

[binovc]

Ok, thanks again.

 

[Charles (in GA)]

I would consider putting a disconnect outside when you move the meter. Its handy to have and there are situations where you may need to disconnect the power from outside. Pulling the meter is generally dangerous and not advisable. Being able to kill the power outside also makes it safer for you to work in the inside panel if you need to.

Charles

 

[pattenp]

I'll second that motion.

I would consider putting a disconnect outside when you move the meter. Its handy to have and there are situations where you may need to disconnect the power from outside. Pulling the meter is generally dangerous and not advisable. Being able to kill the power outside also makes it safer for you to work in the inside panel if you need to.

Charles

 

[D.J.]

It has been most common to not pull the meters at structure fires for several years now as local utilities now send personnel out to disconnect the wires at the poles or ground mounted transformers.

 

[Norcal]

Pulling meters can be very hazardous, there is no overcurrent protection between the transformer & the meter can, + the avail. fault current can be high, so it can be a recipe for disaster, so make me vote #3 for a outside disco.

 

[binovc]

Glad you all are chiming in about the disconnect. It was my original intention to have one (because I assumed they were required, and also the safety/convenience of working on the inside breaker panel), but I couldn't even find one at local Lowes, then found out about the local code of not being required. So I figured maybe that's just the common thing to do. I will either find a meter socket with a built-in disconnect (if that exists), or a separate disconnect.

 

[Charles (in GA)]

Glad you all are chiming in about the disconnect. It was my original intention to have one (because I assumed they were required, and also the safety/convenience of working on the inside breaker panel), but I couldn't even find one at local Lowes, then found out about the local code of not being required. So I figured maybe that's just the common thing to do. I will either find a meter socket with a built-in disconnect (if that exists), or a separate disconnect.

There are several ways to go, meter with built in disconnect, and meter, built in disconnect and also place for about 4 or 6 breakers. Which is good as it allows you to take power to a outside A/C unit, outbuilding, garage, etc, without having to take the wire in the house..

Meter box in the top pics is a Siemens with a 200 amp disconnect under the lid on the RH side of it.

Charles

 

[VRR]

Outside disconnect between the main panel and secondary panel along with ground rod at both panels is code as of 2009. Your pdf diagram doesn't show the ground rod at the secondary panel or the disconnect.

 

[binovc]

VRR - I do show a ground connected from the neutral/ground bus bar to a ground rod at the outdoor main panel. This panel has a single neutral/ground bus bar. My 2nd pdf (located in post #3) shows a ground conductor coming back from the sub panel to that neutral/ground buss bar. So you are saying I would need a second ground rod (which would be pretty much the same location as the existing ground rod) to run the ground conductor from the inside sub panel? Thanks for clarifying exactly where I need ground rods, and where the ground conductors should be connected differently from the pdf.

 

[pattenp]

An additional ground rod is not needed for the secondary panel if the secondary panel is located within the same building as the primary panel. Additional ground rods are needed if only one ground rod is used and the one ground rod does not meet the required 25 ohms or less of resistance to earth (NEC 250.53). The common practice is to use 2 ground rods at the building because it’s easier than having to do a resistance test to show that one ground rod meets the 25 ohm or less requirement. If the secondary panel is being placed in a separate building such as a detached garage then a ground rod(s) would be required at that building (NEC 250.32).

Outside disconnect between the main panel and secondary panel along with ground rod at both panels is code as of 2009. Your pdf diagram doesn't show the ground rod at the secondary panel or the disconnect.

 

[binovc]

Ok, and I also found out the following (from mikeholt.com), which answers my question about putting the ground rods next to each other:
"When the resistance of a single ground rod is over 25 ohms, an additional electrode is required to augment the ground rod electrode, and it must be installed not less than 6 ft away. No more than two ground rods are required, even if the total resistance of the two parallel ground rods exceeds 25 ohms."
Thanks.

 

[binovc]

Lowes guy advised me that it is better to run my 220 breakers from the extra spaces available inside my combination meter socket/ load center rather than from the inside breaker cabinet. He said if I run everything from the inside cabinet, I would notice things like the lights dimming when a 220 equipment kicked in (like A/C compressor, dryer, welder in the shop). Is there anything to this? Why would my 110 circuits care where my 220 circuits are placed, don't they all feed off the main service entrance? The meter/load center combo I have has a main 200 amp breaker plus 4 additional spaces (I can run two 220 breakers there). The available circuits are downstream of the main 200 amp breaker - so all the circuits I could ever install would all be downstream of this breaker.