Lost the neutral

Reply

  #1  
Old 10-15-04, 06:47 AM
bvlynch
Visiting Guest
Posts: n/a
Lost the neutral

Here is a strange one.

A bulb blew on our house lower lighting ring and tripped the breaker . Now only 2 of the lights on the ring work but the other 7 do not ( all on the same breaker ) .
It seems the two working are those nearest the breaker box
I checked the voltage ( i am in the UK so were on 240v ) . on the lights that do not work i get 240v between live and earth , but only 190 - 200 V between live and neutral ????? It seems like i have lost the neutral some how.

I am confused how can a blown bulb cause this ??
 
  #2  
Old 10-15-04, 09:37 AM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
Yes, you lost a neutral. The first time this happens to you it seems strange. But this failure is incredible common. It is a common side-effect of an overcurrent situation (and even a blown lightbulb can create momentary overcurrents). The heat caused by the overcurrent causes an already weak connection to fail. The failure could either be in a non-working outlet, or a nearby working outlet. I don't know if you use those crappy backstab connections, but those are always the first to fail.

It's not a difficult problem to fix, but it requires time, patience, and persistence.
 
  #3  
Old 10-15-04, 10:59 AM
bvlynch
Visiting Guest
Posts: n/a
Where to start

Thanks for the confirmation of my suspicions . One final question I have 3 LV lights on this ring with a small transformer at each one ( 240v - 24v) . Do you think one of these is likely to be the fault or should i just start from the breaker box ??

The reason i ask is i just laid a laminate floor above where these suckers are :mad

Barry
 
  #4  
Old 10-15-04, 12:28 PM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
Any box on the circuit could be the problem (but the problem is not on the secondary side of a transformer). Start with the dead boxes. Then move to the closest other boxes on the same circuit and work out from there. Save the panel for last. By box, I include not only receptacle boxes, but also switch boxes and fixture boxes.

By the way, no electrical connections should ever be rendered inaccessible. Never.
 
  #5  
Old 10-16-04, 04:44 AM
bvlynch
Visiting Guest
Posts: n/a
Problem Resolved !!!!! thanks

So here is the scoop.

I went to the first light in the ring ( this one was still working ) . Dropped down the light fitting to see three neutral wires hanging in space ( hallejula!!).

Cause i told my wife , the connection block they wire into , the screw thread was bad and the screw was tighening up as if biting on the wires but was not ( the wires were still loose ).

Real cause as above plus ME for not pulling on the wires once tightened to ensure they were secure.

So i tightened the wires , put a used bulb in one of the faulty fittings , threw the switch and................... nothing !!!

Just as i was breaking into my Johnny Mac " You cannot be serious !" routine , i took a deep breath , got a new bulb from the pack , put it in and Eureka !! problem solved .. I had used a dead bulb for the final test

So viewers lessons learned

1. always pull on wires once tightened to ensure they are secure

2. Always make sure your test equiptment is working correctly ( bulb )

Thanks for the help

P.S. the transformers were accessable ,they drop down through the light recess if i need to change them.
 
  #6  
Old 10-16-04, 09:42 AM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
Thanks for the interesting report. But I have one question. How did burning out a light bulb cause three wires to suddenly be hanging in space? I can't correlate the cause and effect. Can you?
 
  #7  
Old 10-16-04, 02:24 PM
bvlynch
Visiting Guest
Posts: n/a
Here is how i see it

The neutrals were not secure . The fitting is the sort that twists 90 degrees to lock in place . The one to the fitting must have made contact to the connector , the ones to the following lights was just touching this one , not secure .

When the buld blew the current ( spark ) must have been enough to break contact between the touching neutrals.

When i dropped the fitting ( rotated it 90 degrees ) the neutrals ( 1.5 mm solid core) just stayed where they were in space and did not move with the fitting as the live and earth did.

remember were on 240v 6amp wiring here , dont know if this makes a difference . I still think it was a strange one , thats why i bounced it off you
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: