My current house has a 200 AMP Main Panel. I added a new guesthouse and will be moving the overhead incoming electrical line underground going to a new 400 AMP main panel in the guest house (because it's closer to the utility pole) and then run a new 200 AMP underground to my current house and will need to convert the existign 200 AMP main panel to a subpanel without a meter. I don't want to rewire everything there, so my thoughts are they will pull the meter and provide a cover, but then it's up to me to make the main connections from the new main.

Can I just wire the 2/0 wires into the old lugs and get some type of jumper bars to close the gap where the meter used to be, or can I buy such jumper bars, or what is best? Thanks for th advice.

Sorry, but you will have to do some work to that 200A panel.

First off, you will have to run 3 2/0 cables and a ground (don't have the code book here to get the size) from the 400A panel to the 200A sub panel. Conduit sizing, fill and whatnot come into play here. There are also some grounding issues that will have to be done correctly. I won't go into all that, I don't know the physical layout and distances.

The neutral conductor will have to be connected to the buss bar that now has the neutrals and grounds in it. The bonding jumper and all the ground wires will have to be removed from that buss bar. ONLY neutrals go into that one and it must be electrically isolated from the panel case.

IF your panel has the room and is rated for it, another buss bar will have to be installed for the ground wires. It will have to be bonded to the panel case like the other one was. If you can't do this you will have to replace the panel.

Some panels have two neutral/ground buss bars in them already and can be split for exactly this setup. Somewhere on the label there will be some information on this.

Do it right, because you are going to have to get this inspected. Do it right even if you don't get it inspected. If you are unsure of all the requirements, call an electrician.

EPM

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Originally Posted by EPMiller

Sorry, but you will have to do some work to that 200A panel.

First off, you will have to run 3 2/0 cables and a ground (don't have the code book here to get the size) from the 400A panel to the 200A sub panel. Conduit sizing, fill and whatnot come into play here. There are also some grounding issues that will have to be done correctly. I won't go into all that, I don't know the physical layout and distances.

The neutral conductor will have to be connected to the buss bar that now has the neutrals and grounds in it. The bonding jumper and all the ground wires will have to be removed from that buss bar. ONLY neutrals go into that one and it must be electrically isolated from the panel case.

IF your panel has the room and is rated for it, another buss bar will have to be installed for the ground wires. It will have to be bonded to the panel case like the other one was. If you can't do this you will have to replace the panel.

Some panels have two neutral/ground buss bars in them already and can be split for exactly this setup. Somewhere on the label there will be some information on this.

Do it right, because you are going to have to get this inspected. Do it right even if you don't get it inspected. If you are unsure of all the requirements, call an electrician.

EPM

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Thanks for the answer. I think I understand what you are saying about the neutral and ground separation. Certainly don't want to have to install a new panel and redo all the wiring going into it - that would be a big job and I wasn't planning on tearing up the stucco. I'll have to take another look at the panel and rig something. I already have the 2/0 wiring and ground installed and inspected... it's just the hookup at the panel that is left.

The new guest house panel is a Siemens 400amp main with two 200amp breakers in it - one for the guest house and one for the main house. Attached are photos of the older Murray 200amp main panel that I need to convert into a subpanel. It only has a single ground/neutral bar.

In the first photo you can see the whole panel with the new feeds and greeen ground wire coming in from the bottom... unattached thus far. You can also see the existing feeds coming in from the top, then looping to the connection as shown in the second photo.

For a new neutral bus to separate grounds and neutral, how do I attach it and where do you suggest?

Wow, that will be a miserable panel to use as a sub panel. I am unfamiliar with that meter base/panel so I can't speak authoritatively to whether it is acceptable for that use or not. Stanfortyman?

First off, I can hardly see the existing neutral/ground bar, and there's no room for another bar unless there is enough space above the meter assembly to use for that purpose. It also appears that the existing neutral lug (with the white taped cable) is not able to be isolated electrically from the panel case, so that will become the new ground connection (green wire). If you CAN remove a bonding jumper and isolate that bar, do it, and attach the WHITE marked cable to that lug.

It is much easier to install a new ground bar. Mount it securely to the case and bond it like the old one was. (Make certain there is no paint underneath that connection) and connect the green cable and all the ground wires to it. Otherwise the white marked cable will have to connect to the new neutral bar, which must be electrically isolated from the panel case and all the neutral (white) wires will have to be moved to it. Since this is a detached structure, the existing grounding cable and stake will stay connected to the GROUND buss, whichever one that is.

The connections for the new red and black cables are the two lugs right above the yellow sticker. You will have to get two bars to insert in the meter sockets to connect them to the breaker buss bars. I have never done that myself, but I would think you could get something to use at an electrical supply house. Just don't use some random pieces of aluminum or rusty steel. You must have really good electrical contact there. If there is resistance, the connections will heat up, possibly causing your feeder cables to ultimately burn off or something equally bad. Of course then you can replace the whole thing with a more suitable panel. :eek:

Quote:

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Originally Posted by EPMiller

Wow, that will be a miserable panel to use as a sub panel. I am unfamiliar with that meter base/panel so I can't speak authoritatively to whether it is acceptable for that use or not. Stanfortyman?

First off, I can hardly see the existing neutral/ground bar, and there's no room for another bar unless there is enough space above the meter assembly to use for that purpose. It also appears that the existing neutral lug (with the white taped cable) is not able to be isolated electrically from the panel case, so that will become the new ground connection (green wire). If you CAN remove a bonding jumper and isolate that bar, do it, and attach the WHITE marked cable to that lug.

It is much easier to install a new ground bar. Mount it securely to the case and bond it like the old one was. (Make certain there is no paint underneath that connection) and connect the green cable and all the ground wires to it. Otherwise the white marked cable will have to connect to the new neutral bar, which must be electrically isolated from the panel case and all the neutral (white) wires will have to be moved to it. Since this is a detached structure, the existing grounding cable and stake will stay connected to the GROUND buss, whichever one that is.

The connections for the new red and black cables are the two lugs right above the yellow sticker. You will have to get two bars to insert in the meter sockets to connect them to the breaker buss bars. I have never done that myself, but I would think you could get something to use at an electrical supply house. Just don't use some random pieces of aluminum or rusty steel. You must have really good electrical contact there. If there is resistance, the connections will heat up, possibly causing your feeder cables to ultimately burn off or something equally bad. Of course then you can replace the whole thing with a more suitable panel. :eek:

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Thanks for the info. Now that's more of what I was thinking. Yeah, it won't be the prettiest panel in the world... mainly due to some cramped space, but on the other hand... I have a lot of extra wire bundled up on the left of the breakers, so it looks uglier now than it is.

I think this is my plan:
1. Either jumper across where the meter was, or (preferred) move the lugs from the lower part to the upper part of the meter connector, thus eliminating the need to jumper across a gap and at the same time making more room in the left side of the enclosure.
2. Possibly punch a hole in the separation panel to fed the neutral wires though and attach the neutral bus bar on the left side where I'll have plenty of room. The separation between the left and the right is only needed when it was a main panel. As a "sub" panel it really isn't required for code requirements (just a guess :confused: ).
3. Attach a new neutral bus, not bonded to the panel.
4. Separate the neutral lug from the connecting bar and attach it using a plastic separator plate to the panel. Connect it to the neutral bus bar using some insulated wire (#6 gauge?)
5. Remove all the neutrals off the existing shared bus bar and attach the neutrals to the new neutral.

Given that, it may not be that bad. It will take a little bit of metal work and grinding, but it would be a lot less work than having to install a new panel and doing stucco work. Plus I'd never be able to match up the stucco color, so next on the list would be a whole house (or wall) paint or re-stucco to make it look right.

Sound OK? (Yeah, I know... I take full responsibility. Duh.. ) :rolleyes:

Good news!
The contractors from the power company came (a bit late as usual) and hooked me up on my guesthouse and while it took me many hours to take down the old wires (off the roof riser), clean up the mess and fabricate some stuff, I'm happy with the result and feel it's clean and safe. I'll post a photo maybe tomorrow or the next day when I get a chance and you folks can judge for yourself. The guys switching the power to the new panel said they see folks converting mains to subs all the time. I hear it's quite common in commercial areas as well to do some panel modifications. I'll report back if an inspector tells me otherwise and makes me redo the whole thing. At least for now, I don't have to work on any stucco. Next on my list is to fabricate a new panel to cover both left and right sides of the panel to make ti look like a regular "sub"-panel.

Well, it sounds like you are getting it done. I applaud you getting it inspected. That way you know you are OK. As to fabricating a new cover, sounds great. I wish I could do that kind of metal work.

EPM

HO32,

Would you please append the model number of the new main panel from Siemens? I'd like to take a look at its design and schematic. Thanks

I finally got a photo of the completed panel for those of you who are interested in the final result. The key was to remove the guts that were there to hold the meter. Once that was removed there was plenty of space to mount a neutral bar - isolated from the panel. I added another ground bar to keep things clean - so there is a ground bar up on the left and another one basically where the combined neutral/ground bar was before - down to the right, both connected via a #6 ground wire, connected to the main panel and also grounded locally to a rebar in the ground. I also cut off one the copper bars and then moved the main lugs over. I still want to redo the left panel cover or maybe make a new cover for the whole thing.

Thanks for posting the picture back. Looks like you accomplished what you set out to do. You were wise to get rid of all that meter base mechanism, gave you lots of room to work.

The only criticism I have is those neutrals that run under the hot lugs. I'd like to see them moved away a bit. And I'd still like to see some sort of guard so those hot lugs aren't so easy to accidentally contact if you ever have to work in there. Of course you SHOULD kill the power at the main panel first when doing that.

Congratulations.

EPM

Yes, I agree with both your comments and am not completely done with this yet. Those 2 items (neutrals running under lugs and plastic cover for main lugs) are still on my list.