Double taped electrical panel

Originally Posted By: Mike Parks
This post was automatically imported from our archived forum.



“it clearly states the one wire per terminal rule”


Example: Square D QO series allows two ungrounded conductors.

The above is code compliant.

Mike P.


Originally Posted By: roconnor
This post was automatically imported from our archived forum.



Mike … I knew someone was going to throw the Square-D QO gang type breakers into the mix here … icon_lol.gif


Yes, the code requires one wire per "terminal" unless otherwise listed for that, and some of those breakers are listed for two wires. But I look at the SQ-D QO gang breakers as having two "terminals" ... with a separate "terminal" for each of the two wires that can be connected. The breakers have a special pressure plate with a separate grove in the plate on each side of the set screw for each of the wires. So I look at the grove in the plate as the "terminal", so it really does have separate terminals for each wire, and is not just listed for two wires under one screw (no direct wire-to-wire contact). I think thats a better way to look at it just to keep things simple ... at least in my mind ... ![icon_lol.gif](upload://zEgbBCXRskkCTwEux7Bi20ZySza.gif)

P.S. I am not aware of any breakers that are listed/acceptable for two conductors under one "terminal" screw, with direct wire-to-wire contact.


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: Dave Nix
This post was automatically imported from our archived forum.



Hi Robert,


Thanks for the welcome!

The danger of the wires being unprotected is that if there is an overload to whatever these wires supply, there isn't any breaker to trip. If there happens to be a main breaker before this panel, the danger is still present because the size of these wires will only carry so much current before they get too hot. Also, if there happens to be a short between these wires or a short to ground, fire is eminent.

Your assesment of the two wires under one screw is right on! This too leads to heat build-up.


--
Dave Nix
Electrical Matters

Originally Posted By: jpeck
This post was automatically imported from our archived forum.



Mike is correct.


One terminal with a captive plate designed for two conductors. Thus, those breakers are approved for two conductors under one terminal.

There is but one terminal screw for that captive plate, you cannot tighten the two conductors independently, thus you have one terminal (if you loosen the terminal to remove one conductor, you have also loosened the other conductor).

Two conductors under one terminal designed for two conductor will not produce unwanted or undesirable heat at the terminal, provided (just like with a terminal for one conductor) that the terminal is properly made up and torqued.


--
Jerry Peck
South Florida

Originally Posted By: roconnor
This post was automatically imported from our archived forum.



Jerry … again, you missed the point. And the code term “terminal” does not mean “screw”, even though it includes the set-screw type.



Robert O’Connor, PE


Eagle Engineering ?


Eagle Eye Inspections ?


NACHI Education Committee


I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: jpeck
This post was automatically imported from our archived forum.



roconnor wrote:
Jerry ... again, you missed the point. And the code term "terminal" does not mean "screw", even though it includes the set-screw type.


Robert,

No, it is you who has missed miss the point, you are trying to apply your own terminology to the breaker designed for two conductors. Thus I was trying to explain to you why you were incorrect in a manner in which you might understand.

Let's try it another way.

If you look at the sides of the Square D breakers, it states that it will accept 2-14, 2-12, 2-10. The breaker itself has been identified for that use, two conductors for one terminal.

No disrespect, but if you would spend less time and effort trying to take my posts apart and respond negatively to them, you would have more time to think about what you are posting and check things, such as the sides of those breakers.

Maybe this will help you. (highlighting with bold and underlining is mine)

110.14 Electrical Connections.
(A) Terminals. Connection of conductors to terminal parts shall ensure a thoroughly good connection without damaging the conductors and shall be made by means of pressure connectors (including set-screw type), solder lugs, or splices to flexible leads. Connection by means of wire-binding screws or studs and nuts that have upturned lugs or the equivalent shall be permitted for 10 AWG or smaller conductors.

Terminals for more than one conductor and terminals used to connect aluminum shall be so identified.

The Square D breaker is "so identified. They include "terminal parts", such as "pressure connectors" which are used to "ensure a thoroughly good connection without damaging the conductors".

Seems pretty clear to most people.


--
Jerry Peck
South Florida

Originally Posted By: roconnor
This post was automatically imported from our archived forum.



roconnor wrote:
I think thats a better way to look at it just to keep things simple ... at least in my mind ... ![icon_lol.gif](upload://zEgbBCXRskkCTwEux7Bi20ZySza.gif)

The real point of the posts is to have a practical discussion about home inspections and helping to keep clients safe, and not to debate fine points of the codes when the real intent has been conveyed. There are plenty of codes sites where that can be debated. Does that help to explain why I think the real point is being missed?


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: jpeck
This post was automatically imported from our archived forum.



roconnor wrote:
Try to think outside the box on this one from a different viewpoint, that is also based on a discussion I had with a Square-D engineer a while back. Conventional thinking is that the special SQ-D QO breakers have only one terminal screw/plate so that they need to be listed for two conductors, which they are. But, that?s not the whole deal.

The real intent of the code for conductor terminations under 110.14(A) is that there be a good conductor connection, without wire-to-wire contact unless it?s specially designed for that. Plus, there is no definition for ?terminal? in the code, and it doesn?t state only one wire per screw. So you could consider that the wires have separate termination points at the end of each wire on the special SQ-D breakers, and therefore meets the intent of that code section.


Robert,

Outside the box or inside the box, and from whichever point of view you choose, each terminal must be tightened to a specified torque for proper tightening of the terminal. There is only one screw with which to tighten this terminal, but there are two locations for the conductors. When the terminal is torqued properly, you have just made up one terminal, which has two conductors.

I agree that there are a few terminal rated for two conductors where there is conductor to conductor contact, however, most two conductor terminals do not have conductor to conductor contact, the terminal is typically designed so that all current flow go from each conductor through the terminal, not through the other conductor.

The listing and labeling, and the instructions with each device, will tell you the torque required for each terminal, and those breakers have on torque for one terminal.

Quote:
So you could consider that the wires have separate termination points at the end of each wire on the special SQ-D breakers, and therefore meets the intent of that code section.


Yes, I guess "you could consider that the wires have separate termination points at the end of each wire". however, the people I've talked with at UL and Sq D consider that to be one terminal, suitable for two conductors, and that is why those breakers are rated for two conductors for that terminal.


--
Jerry Peck
South Florida

Originally Posted By: rsonneson
This post was automatically imported from our archived forum.



Kevin when you state main is double tapped are you saying the the main line coming in is double tapped prior to the main breaker or the main breaker has is double tapped after the breaker? My understanding the main lugs above the main breaker can not be double tapped or it is considered a saftey issue and should be investigated by electrician.



Bob Sonneson


American Home Inspection Technologies

Originally Posted By: roconnor
This post was automatically imported from our archived forum.



R.S. … I think you are on the money there with a double lug on a smaller breaker or neutral buss being a “Safety Concern” … while a double lug on the main is a “Major Defect” (and a real concern due to possible overloading of the feeders) … and what I would call a major defect or safety hazard is what I see from the pic.


Jerry ... I have never gotten a practical/reasonable/direct response from anyone at UL, so I don't bother any more. But I have found that the technical guys and engineers at Square-D are generally very competent and practical.

On the gang breakers made for two wires (like the 15A/20A SQ-D and CH ones) at least we agree that considering each wire has it's own termination point without wire-to-wire contact may be another way to look at it. As an instructor I find it's simple to explain that way. When ya say "one wire per terminal, unless otherwise listed for that per 110.14.A of the NEC" ya might get some blank stares. But if ya explain it as each wire needs it's own termination point without wire-to-wire contact according to current safety standards the light bulb goes on ... ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: Bob Badger
This post was automatically imported from our archived forum.



jpope wrote:
Where are our resident sparkies or engineers when we need them? ![eusa_think.gif](upload://lNFeGuTetUAtwNVgUSOuUzgrGGK.gif)

Mr. Parks. . . Mr. O'Conner. . . Mr. Badger. . . any of you have some additional info for us?


I have been laying low trying to stay out of the cross fire.

Besides you guys know that this is incorrect you do not need one of us to tell you so.

There is no way that the terminals on this breaker are rated for two conductors each.

Now for the part where the shooting may start.

Going by just what I can see in the picture the only definite violation is the "double tapping"

From just the picture there is no way to tell if we have another violation in tapping the supply side of the main.

There are code compliant ways this could be done.

Lets say the breaker terminals where rated for the double tapping if those conductors only run to a another correctly sized disconnect right beside this panel, that would be OK.

The code allows up to six service disconnects, as long as each one has the proper overcurrent protection you would be all set.

The total ampacity of the six disconnects can exceed the ampacity of the service conductors as long as the calculated load is less than the ampacity of the service conductors.

Exception No. 3 230.90(A)

Another possibility would be that the service disconnect is at the meter and the double tapped breaker is "extra" not likely but it happens sometimes.

A legal way to tap the supply side of this breaker would be a 3 way splice ahead of this breaker.

Just putting out some possibility's to think about.


--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: Bob Badger
This post was automatically imported from our archived forum.



Quote:
P.S. I am not aware of any breakers that are listed/acceptable for two conductors under one "terminal" screw, with direct wire-to-wire contact.


For a typical house this is true, once you get into equipment rated more than 200 amps all bets are off. ![icon_razz.gif](upload://rytL63tLPMQHkufGmMVcuHnsuWJ.gif)

Once you get above 200 amps you may start to see the use of parallel conductors, this is strictly a design choice not a code requirement.

It is quite possible to get a greater than 200 amp breaker that has terminals with one hole each that accept two conductors.

For a large dwelling unit with a 400 amp single main an electrician may chose to run two sets of 4/0 conductors per phase and order a main breaker that is listed to accept two conductors per terminal.

Sometimes each conductor gets its own "hole" or sometimes both conductors will be stacked in one hole.

The only way to know if it is a violation would be to read the terminal info off of the terminal or breaker.


--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: roconnor
This post was automatically imported from our archived forum.



Bob Badger wrote:
Quote:
P.S. I am not aware of any breakers that are listed/acceptable for two conductors under one "terminal" screw, with direct wire-to-wire contact.
For a typical house this is true, once you get into equipment rated more than 200 amps all bets are off. ![icon_razz.gif](upload://rytL63tLPMQHkufGmMVcuHnsuWJ.gif) ... The only way to know if it is a violation would be to read the terminal info off of the terminal or breaker.

Yes, I meant for the usual residential service panel. But wouldn't even the larger mains/lugs that could have two wires have a special semi-circular shape, so you would get a good connection even with some wire-to-wire contact ... and avoid the situation like that indicated by the top terminal with two wires shown in the post picture.

Bob Badger wrote:
For a large dwelling unit with a 400 amp single main an electrician may chose to run two sets of 4/0 conductors per phase and order a main breaker that is listed to accept two conductors per terminal.

That?s really just for the service feeders, right ? and wouldn't that be "parallel conductors" that are required to be ?electrically joined at both ends to for a single conductor? (310.4). That last part seems a little sticky.

Also for what we are really discussing here, which is a double lug on the main for a subpanel feeder, isn?t it also not allowed since it would be equipment tapped on the supply side of the main disconnect (i.e. the main breaker with the double tap). Maybe a little more input.


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: Bob Badger
This post was automatically imported from our archived forum.



roconnor wrote:


But wouldn't even the larger mains/lugs that could have two wires have a special semi-circular shape, so you would get a good connection even with some wire-to-wire contact ... and avoid the situation like that indicated by the top terminal with two wires shown in the post picture.


I believe the elliptical shape is used as it helps keeps the wires stacked instead of letting the conductors fan out to the sides.

By keeping the conductors stacked the set screw can apply pressure to the entire conductor.

The breaker in this picture certainly does not have terminals made for two so that one is a violation.

Here is a lug rated for one 600 KCMIL - #4 AWG or two 250 KCMIL - #1/0 AWG.



This is not a breaker lug, but a breaker lug for two conductors would have that "hole shape" or have a very oval shape.

roconnor wrote:


Bob Badger wrote:
For a large dwelling unit with a 400 amp single main an electrician may chose to run two sets of 4/0 conductors per phase and order a main breaker that is listed to accept two conductors per terminal.

That?s really just for the service feeders, right ? and wouldn't that be "parallel conductors" that are required to be ?electrically joined at both ends to for a single conductor? (310.4). That last part seems a little sticky.


Well yes and no, this could be for a feeders, however I doubt highly that many dwelling units have 400 amp feeders leaving the service panel.

In the work I do the answer would be yes, we may run parallel conductors for a feeder from a lug like this.

roconnor wrote:
Also for what we are really discussing here, which is a double lug on the main for a subpanel feeder, isn?t it also not allowed since it would be equipment tapped on the supply side of the main disconnect (i.e. the main breaker with the double tap). Maybe a little more input.


Well when we talked about surge suppression tapped on the supply side of the service disconnect we clearly had a violation of "230.82 Equipment Connected to the Supply Side of Service Disconnect."

However you could come from the meter to a trough and splice there and feed up to six panels each with a main breaker.

Now you would have 6 service disconnects, the maximum allowed.

The service disconnects when there is more than one have be located together.

For the code interested.

Quote:
230.71 Maximum Number of Disconnects.
(A) General.
The service disconnecting means for each service permitted by 230.2, or for each set of service-entrance conductors permitted by 230.40, Exception Nos. 1, 3, 4, or 5, shall consist of not more than six switches or sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard........it continues


And

Quote:
230.72 Grouping of Disconnects.
(A) General. The two to six disconnects as permitted in 230.71 shall be grouped. Each disconnect shall be marked to indicate the load served.


This can come up in a single family dwelling unit when the original small panel runs out of space, there are code compliant ways to add a second panel beside the first.

Most commonly this is done as in the photo, incorrectly but it can be done correctly by a sparky that cares.

Of course I would rather see the under sized panel ripped out and replaced rather than one added to the side.


--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: roconnor
This post was automatically imported from our archived forum.



Bob Badger wrote:
I believe the elliptical shape is used as it helps keeps the wires stacked instead of letting the conductors fan out to the sides.

Seems like that special shape would be to get good connector metal-to-wire contact on larger lugs made for two wires. To me, the electrical connection from the wire-to-wire contact without twisting is questionable.

For a single wire on a standard breaker with a pressure plate, tightening the set screw will tend to compress the wire and get good surface contact on two sides of the wire. Add another wire to that standard breaker, and to me you have about half the intended contact area, with a questionable wire-to-wire connection with less surface area on one side.

Where I was going with my other comments is that larger residential services with twin panels (greater than 200A) should be done with a wiring trough, splice box, or separate MD ahead of the service panels that splits the feeders to comply with the code. So I think you really shouldn't have a situation like the one shown in the post.


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: Bob Badger
This post was automatically imported from our archived forum.



Robert as one who has used these two conductor lugs I can tell you that they do rely on the conductor to conductor contact to a large extent.


Remember there is no pressure plate on these and if a great deal of the current did not carry through one conductor to the other it would have to travel through the set screw itself which most times is a much smaller diameter than copper conductor.

As to the other issue there would be no code violation for me to tap the service conductors in one panel and feed one another service panel beside it.

This could be done with any listed wire connector.

You are allowed up to 75% fill for the splices themselves, if I was to do this my first choice would be insulation piercing taps.



There is no requirement that the tap to another service disconnect be outside the original service equipment.

You just can not double tap a breaker not rated for it.


--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: roconnor
This post was automatically imported from our archived forum.



Bob … I will defer to you. Just doesn’t seem like a good thing to rely so heavily on reduced wire-to-wire side contact or smaller set screws to make a good electrical connection. But I like your first choice connector.


I think we are still on the same page with the residential panels in general, and this one being a real issue.


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: rray
This post was automatically imported from our archived forum.



Well, this thread is basically useless for someone who just found it. What happened to Mr. Luce?


I have this little disclaimer in my report:

Quote
HOMETEAM highly recommends that any additional recommended inspections, evaluations, consultation, repair, and/or replacement be performed by qualified experts or licensed specialists before close of escrow. For repairs which might require a licensed specialist, Client should request repair and remediation by such licensed specialists in lieu of seller, and Client should request receipts for such work since seller, home owner, and other unlicensed individuals cannot guarantee or warranty their work.
Unquote


I also tell me my Clients that if any licensed professional disputes anything in my report, just have them put their opinion in writing, on their company's letterhead, dated, and signed. I have gotten quite a few phone calls from Clients thanking me for such advice.

![icon_twisted.gif](upload://xjO326gspdTNE5QS3UTl0a0Rtvy.gif)


--
Home inspections. . . .
One home at a time.