electrical wiring questions

[timO']

I am upgrading my service form 100A to 200A to accommodate the new air handler. Although there is an existing 100A breaker panel, I am putting two 100A breakers after the new meter, and branching one to the old breaker panel and the other to the air handler. There is a ground electrode outside adjacent to the existing meter. It a #8 copper and it goes to the old breaker panel. The clamp is loose, and it looks pretty crappy, but it is definitely in the ground. don't I need to restore the integrity of the clamp and connect it elsewhere. Where and how? The new air handler has two CB's in it; a 60A and a 30A. It is a 220V appliance. What size wire and what type of box goes in the crawl space to power this? the air handler mounted on a pad, with clear space all around it. How close to the unit does the box goe and what type of wire between the box and the air handler? Can the new box be mounted directly to the air handler? I was previously advised that an indoor disconnect would suffice. Dose it need have overload (CB) in it even though the air handler has its own pair of CB's? I was planning to run a 100A branch circuit to the air handler off the meter and another

100A branch to the existing breaker panel. Comments and advice are welcomed.

[RBM]

You probably need to talk to a local electrician for local service requirements. Normally you would either come off of the meter with a 200 amp feeder into a main panel, then run the 100 amp feeder out of that panel . You could also run a 200 amp line off the meter into a panel with two 100 amp disconnects, then run 100 amp feeders to the two sub panels. It would seem to me that if the "air handler" has disconnects built into it, you would run the 100 amp feeder directly to main lugs inside the unit, and no other disconnect would be required at or near the unit

[timO']

thanks for the ideas.

I had them install the heat pump based on the advice that it wouldn't be necessary to upgrade the old breaker panel. I'm thinking that a disconnect will suffice at the air handler since it has its own CB's. what's the generic description for the item that connects to the meter to create two branch circuits? I'll document what I've got planned and ask the inspector. I already got a permit, and the electricians in my area are all rip off artists because it's a high growth rural area and they can get away with it. but not with me.

[John Grabowski]

If the ground rod is your only ground connection then you need at least a #4 copper wire for your grounding electrode conductor on a 200 amp service. You should also have two ground rods at least six feet apart (Sixteen feet is optimal). If you have a copper water pipe for your water service (Not a well) then you would run the #4 to that and the ground rods can be connected with #6. The grounding electrode conductors must be joined in the main service panel (Not subpanels) or the meter to the neutral conductor. All of your interior metal piping must be bonded together and #6 is sufficient for that.

Probably a four conductor #2 copper cable is best. I'm not 100% sure that the 60 and 30 amp CB's in the unit would suffice as the only disconnects. Check the installation manual. One of the reasons for the disconnects is for the safety of service people working on the unit. If those two circuit breakers don't isolate the power from where servicing needs to be performed, then you should have a 100 amp disconnect within sight of the unit. Sometimes it can be mounted directly on the unit, but care must be taken to not damage internal components when mounting.

the air handler mounted on a pad, with clear space all

Check the installation manual for wire size and temperature requirements. Also check the nameplate.

Can the new box be mounted

No since you will have a 100 amp circuit breaker outside under the meter. That will protect the whole line.

I was planning to run

You will also need a GFI 120 volt 15 amp receptacle near the unit for servicing. I think a light is required as well.

John Grabowski

[John Grabowski]

Depending on how you plan to do the installation it would be distribution panel or a weatherproof trough with two 100 amp weatherproof main breakers.

[Bud--]

Note your original service panel is now a subpanel. The neutral bar is likely connected to ground/enclosure in the original panel - often by a green screw. That bond should be removed and ground wires, if any, on the neutral bar moved to a ground bar which may have to be installed.

The air handler should have instructions that should be consulted. The wiring requirements for the air handler are based on information on the name plate, which is not supplied here. Advice given based on unit circuit breakers, which is all we have, is likely heavier than if based on nameplate. The air handler includes a compressor, which is a major electrical motor load, and rules for motor loads are somewhat arcane.

-- bud--

[John Grabowski]

Good important point about the ground wires Bud. I forgot about them needing to be moved over.