Originally Posted By: dvalley This post was automatically imported from our archived forum.
Tell me something Sparkies,
I realize that double lugging in a service panel is a red flag but can someone tell me why this is a safety issue. All I can come up with is that the breaker will trip sooner than anticipated because too many amps are traveling through two wires at a single 15 amp breaker.
 But I cannot figure out why this is considered a safety issue. 
Will the 14/12 gauge wires melt at the ends because of the doubled amperage at the connection point?
Originally Posted By: jmyers This post was automatically imported from our archived forum.
David,
The breaker that is being double lugged (or tapped) has to be rated for that purpose. Meaning the wire lug has to be UL listed for two wires in the lug.
If you perform a search on the message board you will find several different reason why double lugging is a safety concern. Try typing in the words "double tapped" or "double lugged".
Originally Posted By: lfranklin This post was automatically imported from our archived forum.
I guess I half to say Mr. Myers is correct. No No wait a minute. It could be that someone other than an electrician has been around and you better look even harder.
Originally Posted By: jmcginnis This post was automatically imported from our archived forum.
By the way David… you won’t get “double amperage” just because someone connected two hot wires to the same breaker… you will still only get, at most, whatever the breaker is rated for… the circuit breaker determines the ampacity of the entire circuit…
Originally Posted By: jmcginnis This post was automatically imported from our archived forum.
David… why be sorry you asked? Everyone learns from everyone else’s questions… and no one knows everything… I find that this forum constantly causes me to question my knowledge and to do research…by the way… the simple answer to your double tapping question is … if the lug is not rated for double tapping then there is a greater chance of having a bad connection, resulting in heating and burning at the connection point…especially if you mix wire sizes at that point … for example #14 and #12 together… since #14 is slightly smaller in diameter, it won’t be as tight in the lug as the #12 and then result in arcing…
Originally Posted By: dvalley This post was automatically imported from our archived forum.
John,
Thank you very much.
A very simple answer to a very simple question.
I was going to research this simple question but figured new inspectors could pick up on a new tip.
About researching subjects...I have never used the search button on this message board. I am now aware that this feature is available. This is a valuable tool for anyone who is trying to get an answer to his/her questions.
Again, Thank you for the info. gentlemen.
Have a great Inspection 
Originally Posted By: jfarsetta This post was automatically imported from our archived forum.
Dave,
Here it is in a nutshell (kinda)...
If the screw lug is not rated to carry two wires, then theoretically one wire can be held tighter than the other (or looser, depending upon your mood at the time of the inspection). A looser connection can mean higher resistance, and higher resistance leads to heat build-up, and heat buildup leads to... well you get the pisture.
Sometimes, folks will double-lug with a #12 and a #14 to a 15 amp breaker. This is a lolapalooza (love that...) in that a loose connection is surely guaranteed.
Now, the reality of the situation is that the local electrical inspectors almost NEVER flag the most common double-lug: the doorbel transformer sharing a common breaker with something else.
Double lugs are the simplest to fix. A pigtail to the breaker and a wirenut will satisfy most electrical inspectors. A more dangerous, and more common, defect I find is the common neutral with no common trip mechanism.
Originally Posted By: dvalley This post was automatically imported from our archived forum.
Joe,
Thanks for the info.
You are stating that most electrical inspectors will approve a pigtail to a wirenut in order to correct the piggyback. Is this your recommendation to your customer or do you recommend they install mini-breakers. My feeling on this is that this will eventually overload the service panel if this is done too many times. To what extent do we start doing (Lectricalman)calculations when we see too many wirenuts or mini-breakers?
Can you give me a bit more detail on the defective common neutral with no common trip mechanism.
Originally Posted By: jmyers This post was automatically imported from our archived forum.
David,
All of this from a home inspector. Are you sure you will be doing load calculations while you are pretending to be a home inspector? 
The absolute best thing you could possibly do is to recommend an electrician perform an evaluation of the electrical system in the home.
I certainly would not state the panel is overloaded because of the double taps, especially if they were approved for that use.
Sometimes you have to assume the electrician that wired those circuits knew what they were doing. The other times you should have an electrician come in a verify the last electrician knew what they were doing. Know what I mean?
Originally Posted By: jremas This post was automatically imported from our archived forum.
The Square D QO series IS rated for double taps. There is another brand, but it escapes my mind right now. If you see the Square D QO, then it should be rated for doubles. I don’t like it but that is the way they rate it at the factory. You would think it would be safer, but there can be a bad side to it. Example.
A 20amp circuit designed for 80% continuos load(3hours or longer) or 16amp. You now double tap with another circuit, lights, etc or whatever that has a continuous load of 4 amps. Now you have exceeded the design of that circuit. Most breakers are rated to take 80% of the continous load for up to 3 hours. If you plan on exceeding the 80% rating of a breaker for a continous load then you need to replace the breaker with a continuous load breaker rated at the full 20amp. A standard 20 amp breaker is designed for 20 amps as long as the load is less than 3 hours continous. However, not many items in the home run for 3 hours or more.
--
Jeff Remas
REMAS Inspections, Inc.
Northeastern PA & the Poconos
www.NEPAinspector.com
Originally Posted By: rray This post was automatically imported from our archived forum.
I’m confused by the terminology we are using. I have always used “double tapped” as meaning that two hot wires from two different circuits are going to one circuit breaker. I have always used “double lugged” as meaning that two ground or two neutral wires are under the same screw.
With those two definitions, I don't know of any panel that is specifically okay for double tapping. I think that is what the circuit breaker is for. I do know of several panels that are okay for double lugging. In fact, I just checked my brand new Murray JA1100, and it is rated okay for double lugging.
Originally Posted By: jmyers This post was automatically imported from our archived forum.
Russel,
While your defenition and explanation comes closer to the real facts, I believe everyone has come to use those terms as meaning the same thing....two wires under one termination. 
Originally Posted By: rray This post was automatically imported from our archived forum.
Thanks, Joe. I don’t use them to mean the same thing and probably never will. I call out both double tapping and double lugging. But if the manufacturer states that his panel is okay for double lugging, I also point this out to the Client. I consider double tapping to always be wrong, double lugging not necessarily so.
Originally Posted By: Dennis Bozek This post was automatically imported from our archived forum.
Well believe it or not…lol…I agree with Russ. However, and there has to be a however here, double lugging the neutrals is forbidden but you can tie two ground wires into the same umm lug. This is acceptable mostly because the ground wire is not a current carrying conductor…or let us hope not.
Granted both the SQD QO and CH breakers are rated for double tapping but as an electrician I do not believe in doing that and would most assuredly install either another breaker for the double tap or a mini breaker.
Whenever possible I always put a single wire on a single connection in a panel.
-- This information has been edited and reviewed for errors by your favorite resident sparky.
Originally Posted By: jmyers This post was automatically imported from our archived forum.
Dennis,
I have a technical question for you and since you are an electrician this should be realitively easy for you.
You had stated that only one neutral per termination. Grounds can be terminated per manufacturer's specs. I agree, that is what the good book states.
Since you are not allowed to place two neutrals under one termination, is it ok to place one neutral and one ground under the same termination? (same wires from the same circuit, or seperate wires from different circuits) Please explain your answer.
No No wait a minute. It could be that someone other than an electrician has been around and you better look even harder.