residential- tapping onto main breaker

Status
Not open for further replies.
T

thomasjohnschulte

Member
I've checked NEC 110.14A --as per L.A. code inspector's recommendation. No clear answer.
The on-site and retired electrical engineer.....oh, forget him.
Can I connect a second wire to the Load of a 150A main breaker?
I would use a #6 or #8 stranded copper. Both load feeds would be copper, and both secured with one set screw/bolt. Copper and AL cannot be on the same 'tie-in' even with use of an anti-oxidant.
I do not see this issue addressed in my NEC code book. Perhaps 110.14-C2 allows a Kearney bolt. Your interpretation.
Tom -- California C-10 430915 (lapsed), S.Carolina RBE2453 (active)
 
You cannot connect to conductors to any terminal unless the terminal is rated for that purpose. Most terminals are not so rated.
 
Basic rule is one wire per lug, unless mfg lists the lug for more than one, as Don pointed out, very few are. Correct code rule is 110.3 (B)
 
There is no reason you cannot connect two conductors to the same pole of a CB.

But typically you cannot land two wires on the same terminal of that CB.

Bring your two wires in and connect them to a single larger wire that connects to the CB terminal. perfectly code legal.

Incidentally, it sounds from your description of what is being planned that you may have one or more tap conductors. There are some rules you need to follow for tap conductors.
 
petersonra said:
...
Bring your two wires in and connect them to a single larger wire that connects to the CB terminal. perfectly code legal.
Click to expand...
That's what Power Taps and Polaris Connectors are for.

But yes, read all of the "Tap Rules" in the NEC to see which one(s) applies to your situation, they are too complex to be based on any speculation from here because they are based on a number of mitigating factors of the installation and use. So if you find one that applies to your situation, be prepared to defend your position to the inspector.
 
electrofelon said:
The two lugs I have seen in the last few years that are listed for 2 conductors per hole are square D L frame circuit breakers, and Eaton CT mounting bases.
Click to expand...
Generally it will be a 400 amp device or larger if it is designed for more than one conductor per terminal.

Some cases lugs can be replaceable or some sort of adapter lug can be utilized that has multiple ports.

If talking about the main breaker in an existing 200A or less load center, making such a tap may not be impossible but may be simpler to find a sub feed plug on unit to install into the load center branch breaker spaces.
 
kwired said:
Generally it will be a 400 amp device or larger if it is designed for more than one conductor per terminal.

Some cases lugs can be replaceable or some sort of adapter lug can be utilized that has multiple ports.

If talking about the main breaker in an existing 200A or less load center, making such a tap may not be impossible but may be simpler to find a sub feed plug on unit to install into the load center branch breaker spaces.
Click to expand...
most of the lugs I have run across that allow two wires are #10 and smaller.
 
I know you said load side, but you can tap the line side of the main breaker with one of these: insulation piercing tap.

Your conductor would then have to connect to a circuit breaker rated for the conductor. These are commonly used to connect small solar inverter panels to much larger main panels.
 
petersonra said:
most of the lugs I have run across that allow two wires are #10 and smaller.
Click to expand...
There are many of those as well. But for 10 AWG and larger (like on the OP's 150 amp breaker) you usually only find multiple conductor rated terminals on devices rated over 225-250 amps (or 400 amp base frame sizes, a 300 amp breaker would be same physical size as a 400 of the same product line in almost all cases).
 
texie said:
I would add that even if you had a terminal rated for 2 conductors it would not allow 2 different size conductors.
Click to expand...
For small conductors like load center/panel board neutral and ground bars the destructions specifically say same size required, however I just looked at the spec sheets for the 6067 mounting bases and L frame breakers I mentioned in post #8 and there is no note saying conductors must be same size, and it is not clear to me from the structure of the wording that the conductors must be the same size. Is that stated anywhere else, perhaps in the listing documents?
 
electrofelon said:
For small conductors like load center/panel board neutral and ground bars the destructions specifically say same size required, however I just looked at the spec sheets for the 6067 mounting bases and L frame breakers I mentioned in post #8 and there is no note saying conductors must be same size, and it is not clear to me from the structure of the wording that the conductors must be the same size. Is that stated anywhere else, perhaps in the listing documents?
Click to expand...
usually you are installing parallel conductors and the need to be same size for that reason, but I suppose if it doesn't state otherwise and they are not parallel they may not need to be same size?
 
kwired said:
usually you are installing parallel conductors and the need to be same size for that reason, but I suppose if it doesn't state otherwise and they are not parallel they may not need to be same size?
Click to expand...
Yeah never really considered different sizes for the large stuff......I guess maybe if you had a main and were making two feeder taps off the load side to different sized sub panels, thats about the only case I can think of where the sizes would be different.
 
electrofelon said:
Yeah never really considered different sizes for the large stuff......I guess maybe if you had a main and were making two feeder taps off the load side to different sized sub panels, thats about the only case I can think of where the sizes would be different.
Click to expand...
You're right, one would never use different sizes for a parallel run of a single circuit, but the case being discussed here is (we assume) a tap to feed something else. Under the right circumstances that can be a different size, but as mentioned, ALL of the applicable "tap rules" must be followed.
 
The way most are designed it doesn't seem that a major size difference would work so well though. Say a typical lug on a 400 amp device wouldn't work so well with say a 350 and a 1AWG conductor both in the lug, a 250 and a 3/0 in same lug may work alright though. Again this would be for connecting feeder taps and not for parallel conductor applications.
 
Status
Not open for further replies.
Top