Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Electrical Wiring
Name: Bruce
Status: Other
Age: 40s
Location: N/A
Country: N/A
Date: N/A

My light bulbs were blowing out very quickly, every two or three weeks, to be exact. An electrician looked at my wiring and told me that my switches were wired incorrectly, that the switch was on the "neutral" instead of the "hot" wire. He rewired all of my switches and now my light bulbs don't blow out as quickly.

Why does switching the neutral make light bulbs blow out so quickly?

I don't know of any way this particular wiring error can have any effect on bulb life. However, if your switches were wired incorrectly, there's a good chance other things were also wrong--things an electrician looking for the cause of this problem would have checked and fixed as a matter of course. (You have to understand that an electrician is going to want to fix everything he sees that's wrong and that might be the cause of your problem, because he doesn't want you to have to call him back, and because he can't wait three weeks to see which fix actually solved the problem. And any electrician who sees a switch wired backwards is going to fix it whether or not he thinks it might be the cause of the problem, because electricians just hate it when customers die while changing light bulbs.)

Anyway, here's one wiring problem that might have been the cause: A neutral wire disconnected at the breaker box will change a pair of 110 volt circuits into a single 220 volt circuit with appliances from one circuit electrically in series with appliances from the other. In this case, if appliances from both circuits were on at the same time, the actual voltage across them would depend on their resistances, and this could easily result in more than 110 volts being across your light bulbs, which would decrease their lifetime significantly. A neutral wire only loosely connected at the breaker box can have a similar but less noticeable effect. Anyone who notices a loose neutral connection is going to tighten it up and give all the other ones a little twist as well just to be safe. Maybe one of these twists actually is what fixed the problem.

Tim Mooney

Click here to return to the Engineering Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory