Jump to content
Strawberry Orange Banana Lime Leaf Slate Sky Blueberry Grape Watermelon Chocolate Marble
Strawberry Orange Banana Lime Leaf Slate Sky Blueberry Grape Watermelon Chocolate Marble
Sign in to follow this  
The Dreamer

Tunnel light issues

Featured Posts

Hi, 

 

Wondering if anyone can offer advice!

 

The tunnel light on our 69 foot narrowboat has stopped working.  The fitting its self is a car type spotlight with a 55 watt halogen bulb in it.  The previous bulb had definitely blown as I tested with both a meter and by wiring it into an accessory plug.  New bulb definitely works as tested on the same day way.  RCB is fine, and indeed I get a reading at the fitting of 12.8 volts, obviously dropping to zero when the switch is flicked.  Yet the bulb will not light, either when in the fitting or when rigged directly to the feeder wires.

 

Not being a sparky I am at a loss as to what to try next, or where the problem lies.  But to my unqualified mind this issue defies logic!

Share this post


Link to post
Share on other sites



M̶y̶ ̶f̶i̶r̶s̶t̶ ̶t̶h̶o̶u̶g̶h̶t̶.̶I̶s̶ ̶t̶h̶e̶ ̶n̶e̶w̶ ̶b̶u̶l̶b̶ ̶m̶a̶k̶i̶n̶g̶ ̶c̶o̶n̶t̶a̶c̶t̶ ̶w̶i̶t̶h̶ ̶t̶h̶e̶ ̶b̶u̶l̶b̶ ̶h̶o̶l̶d̶e̶r̶.̶I̶.̶E̶ ̶a̶r̶e̶ ̶t̶h̶e̶ ̶b̶u̶l̶b̶ ̶t̶e̶r̶m̶i̶n̶a̶l̶s̶ ̶t̶h̶e̶ ̶c̶o̶r̶r̶e̶c̶t̶ ̶f̶o̶r̶m̶a̶t̶,̶a̶n̶d̶ ̶s̶a̶m̶e̶ ̶v̶o̶l̶t̶a̶g̶e̶ ̶a̶s̶ ̶t̶h̶e̶ ̶o̶l̶d̶ ̶b̶u̶l̶b̶.̶ ̶ ̶ ̶ ̶ ̶N̶o̶t̶ ̶s̶u̶r̶e̶ ̶w̶h̶a̶t̶ ̶a̶n̶ ̶R̶C̶B̶ ̶i̶s̶.̶

 

 

 Forget that, I didn't read it properly. 

Edited by rusty69
add a bit

Share this post


Link to post
Share on other sites
26 minutes ago, The Dreamer said:

Hi, 

 

Wondering if anyone can offer advice!

 

The tunnel light on our 69 foot narrowboat has stopped working.  The fitting its self is a car type spotlight with a 55 watt halogen bulb in it.  The previous bulb had definitely blown as I tested with both a meter and by wiring it into an accessory plug.  New bulb definitely works as tested on the same day way.  RCB is fine, and indeed I get a reading at the fitting of 12.8 volts, obviously dropping to zero when the switch is flicked.  Yet the bulb will not light, either when in the fitting or when rigged directly to the feeder wires.

 

Not being a sparky I am at a loss as to what to try next, or where the problem lies.  But to my unqualified mind this issue defies logic!

If you see 12 point something volts at the fitting, yet the good bulb doesn't come on, then that tells you there is a dodgy high resistance joint somewhere in the system. It will show 12V when a meter is put across the contacts with no bulb, but if you fit a bulb in and try switching it on you'll see that the voltage drops away to near zero between the bulbs two terminals. The problem is, it could be anywhere in the circuit, between the battery and the bulb, including bus bars, both 12V and 0V side, fuse/breaker, switch, any joints, or choc block connectors and the spotlight itself. Nothing for it but to methodically, check, undo, clean, or bypass each joint till you find the dodgy one.

I assume by RCB, you mean a resetable overcurrent breaker, MCB is the more usual acronym.

 

Jen

Edited by Jen-in-Wellies
  • Greenie 1

Share this post


Link to post
Share on other sites
24 minutes ago, Jen-in-Wellies said:

I assume by RCB, you mean a resetable overcurrent breaker, MCB is the more usual acronym.

Indeed I did, typo!

 

Thanks for the reply. Very useful, and without knowing the science behind it, I had sort of guessed that I would have to check every connection.

 

Probably will start at the switch, and work forward or backwards from there depending what I find.  My worse nightmare is the thought of having to route 20 odd meters of new cable front to back!

Share this post


Link to post
Share on other sites

A few years ago when I was working of a boat fitter we had a complete box of faulty lamps. They failed as soon as they were installed...not even a flash as the filament failed...have you checked the lamps for continuity across the Filament? Worth a check...it was the cause of a lot of muttering in our yard....they were branded lamps as I recall too. 

Share this post


Link to post
Share on other sites
7 minutes ago, The Dreamer said:

Indeed I did, typo!

 

Thanks for the reply. Very useful, and without knowing the science behind it, I had sort of guessed that I would have to check every connection.

 

Probably will start at the switch, and work forward or backwards from there depending what I find.  My worse nightmare is the thought of having to route 20 odd meters of new cable front to back!

Half split. Test the supply by using the boat hull as a negative and see which half of the circuit is at fault, supply or return.

  • Greenie 1

Share this post


Link to post
Share on other sites
5 minutes ago, frangar said:

...........have you checked the lamps for continuity across the Filament?

 

1 hour ago, The Dreamer said:

.................he previous bulb had definitely blown as I tested with both a meter and by wiring it into an accessory plug.  New bulb definitely works as tested on the same day way.

 

Share this post


Link to post
Share on other sites

Similar problem and symptoms after several goes I stopped out the pop rivet holding the bulb holder to the lamp body, sanded the surfaces and put in a new rivet, problem solved. I doubt yours is the same but it shows how wierd duff contacts can be.

 

Share this post


Link to post
Share on other sites
7 hours ago, catweasel said:

Useful though multimeters are, they can give a voltage across a line drawn with a pencil. 

And the more expensive and sophisticated (higher impedence), the multimeter is the higher the voltage!

Share this post


Link to post
Share on other sites

Having as a boat that had never had a headlight fitted (no, I don’t know why either), it might be best to go down the route of a removable LED lamp. Low power demand, coupled with a rechargeable battery and problem solved without any wiring.

  • Greenie 1

Share this post


Link to post
Share on other sites
11 hours ago, catweasel said:

Useful though multimeters are, they can give a voltage across a line drawn with a pencil. 

Not if there is a 55 watt light bulb in parallel with the meter

Share this post


Link to post
Share on other sites
11 hours ago, catweasel said:

Useful though multimeters are, they can give a voltage across a line drawn with a pencil. 

I have a low impedance meter that I use for general low voltage stuff specifically to avoid spurious readings like that. An ‘ordinary’ meter is used when poking around circuit boards. 

Share this post


Link to post
Share on other sites
1 hour ago, WotEver said:

I have a low impedance meter that I use for general low voltage stuff specifically to avoid spurious readings like that. An ‘ordinary’ meter is used when poking around circuit boards. 

The good old test amp works well. So long as its not LED 84459.jpg

  • Greenie 1

Share this post


Link to post
Share on other sites
Guest
2 hours ago, ditchcrawler said:

Not if there is a 55 watt light bulb in parallel with the meter

Yup. Admittedly not 55W, but I use a panel warning lamp for that purpose. Always served me well. Was useful for exciting our alternator too, when the control panel went AWOL.

Edited by Guest

Share this post


Link to post
Share on other sites
3 hours ago, Stilllearning said:

Having as a boat that had never had a headlight fitted (no, I don’t know why either), it might be best to go down the route of a removable LED lamp. Low power demand, coupled with a rechargeable battery and problem solved without any wiring.

I have a rechargeable LED torch with various brightness settings and rarely go boating without it. Not only a backup tunnel lamp (magnetic, so just place it on the steel facing forwards to suit the steerer), but good for walking a dark towpath or seeing into odd corners of a boat, or when under working boat covers in the dark.

Share this post


Link to post
Share on other sites
1 hour ago, catweasel said:

Yup. Admittedly not 55W, but I use a panel warning lamp for that purpose. Always served me well. Was useful for exciting our alternator too, when the control panel went AWOL.

I've done that as well

53 minutes ago, Peter X said:

I have a rechargeable LED torch with various brightness settings and rarely go boating without it. Not only a backup tunnel lamp (magnetic, so just place it on the steel facing forwards to suit the steerer), but good for walking a dark towpath or seeing into odd corners of a boat, or when under working boat covers in the dark.

I have one specifically for tunnels, rest of the time there is a piece of plastic to isolate the 4 D cell batteries so they are always like new

Share this post


Link to post
Share on other sites

Thanks for your replies everyone!

 

So test leads and multimeter in hand, I set about tracing this back today.  Started at the switch and there was no power, so went back to the MCB.  Nothing at the “fused” side, but obviously I had power at the live side (else nothing would be working).  MCB itself had not not tripped, or at least it has not visibly done so.  After a couple of flicks of the MCB switch, I managed to get power back through it, and when checking the tunnel light, it was working too.

 

so I am relieved that I do not need to run a new cable up to the bow, put am presuming that I should not bank on the MCB not failing again, so will get a replacement ordered and fitted.

 

again all, thanks for the advice and help...

  • Greenie 1

Share this post


Link to post
Share on other sites
10 hours ago, The Dreamer said:

am presuming that I should not bank on the MCB not failing again

Correct. 
 

I’m going to take a guess that the MCB isn’t DC rated. Any chance of a piccy of any markings on the body of it?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.