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Immersion heater switch - neon not lighting up


Machpoint005
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What the title says, really. We have a cauliflower for cruising, but when connected to a shoreline we use the immersion heater for domestic hot water. The heater is working fine, but when I first switch it in the red neon doesn't light up. After a while it starts to glow, and you can tell that the heater is on. 

 

My question is simply: do neon indicators wear out? If that's all it is, I'm inclined just to live with it! The switch assembly is probably the same age as the boat (25 years). It looks like the image below, except that the neon and the switch are side-by-side.

 

1713799836_immersionheaterswitch.jpg.2dca574676531824fe61a19f189de305.jpg

 

 

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7 minutes ago, Machpoint005 said:

What the title says, really. We have a cauliflower for cruising, but when connected to a shoreline we use the immersion heater for domestic hot water. The heater is working fine, but when I first switch it in the red neon doesn't light up. After a while it starts to glow, and you can tell that the heater is on. 

 

My question is simply: do neon indicators wear out? If that's all it is, I'm inclined just to live with it! The switch assembly is probably the same age as the boat (25 years). It looks like the image below, except that the neon and the switch are side-by-side.

 

 

 

 

 

 

I have had neons fail before so yes I would say.

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28 minutes ago, Machpoint005 said:

What the title says, really. We have a cauliflower for cruising, but when connected to a shoreline we use the immersion heater for domestic hot water. The heater is working fine, but when I first switch it in the red neon doesn't light up. After a while it starts to glow, and you can tell that the heater is on. 

 

My question is simply: do neon indicators wear out? If that's all it is, I'm inclined just to live with it! The switch assembly is probably the same age as the boat (25 years). It looks like the image below, except that the neon and the switch are side-by-side.

 

 

I have known them fail, but usually on extension leads.

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11 minutes ago, Machpoint005 said:

Not so much a failure here, as a reluctance to light up. We do get a glow after a while. 

Just so long as that's all it is!

 

 

 

It is either a neon failing or a poor connection. I think a neon is just a glass envelope with gas and an electrode inside it, so if the glass to conductor seal is not absolutely 100% it will leak gas and eventually fail to light up. One I had fail was blackish, so it could have been the electrode had vaporised.

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10 minutes ago, Machpoint005 said:

Not so much a failure here, as a reluctance to light up. We do get a glow after a while. 

Just so long as that's all it is!

 

 

 

The failures I have had were:-

 

1 - Just plain not working, this was in our last house on a fused spur that supplied the burglar alarm. The supply to the alarm was still working though. I did replace it though.

 

2 - Glowing so faintly that it was barely possible to see it was on in daylight. This was in our current house and was the supply to the immersion heater. I didn't specifically replace that one as the whole system got ripped out when we got a new (combi) boiler installed.

 

So not exactly the same as yours but indicative they can go belly up.

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43 minutes ago, Machpoint005 said:

 

You have just elminated any possibility that I might take your remarks seriously!

 

 

So why did they crash a rocket into the moon just so as another spacecraft could collect dust from the moon. If as you say they could get it from NASA or a museum

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49 minutes ago, Tonka said:

So why did they crash a rocket into the moon just so as another spacecraft could collect dust from the moon. If as you say they could get it from NASA or a museum

The lunar material changes in different parts of the moon. More samples improves our understanding. To quote an astronaut, "It's like no cheese I've ever tasted Gromit".

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The problem could be the series resistor that all mains neons need. Neons per se are usually reckoned to have a virtually infinite life, but the inside of the glass can become so black with metal deposited from the electrodes that the glow is too dim to see. If the series resistor has gone high in value there might not be enough voltage for the neon to strike, or it could be glowing dimly and, as the resistor warms up, its resistance drops and the increased current makes the neon glow bright enough to become visible. Or it could be an intermittent joint.

 

Edited by Ronaldo47
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59 minutes ago, Ronaldo47 said:

If the series resistor has gone high in value there might not be enough voltage for the neon to strike, or it could be glowing dimly and, as the resistor warms up, its resistance drops and the increased current makes the neon glow bright enough to become visible.

 

That sounds entirely plausible, thank you! Not only do I know there is no serious problem, but I have a clear explanation for what is happening. 

For some reason, my switch front plate is mounted on its side (switch to the left, neon to the right) but so long as I remember which way is "on" I can live with it.

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9 hours ago, Machpoint005 said:

If that's all it is, I'm inclined just to live with it!

Thereby saving yourself the princely sum of less than a fiver, even if you buy a quality one like, say, a Crabtree. Those neons do fail and I'd say 25 years isn't a bad return from yours even if some do last even longer. Go on, splash out and be "mithered"! :D

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7 hours ago, Machpoint005 said:

 

That sounds entirely plausible, thank you! Not only do I know there is no serious problem, but I have a clear explanation for what is happening. 

For some reason, my switch front plate is mounted on its side (switch to the left, neon to the right) but so long as I remember which way is "on" I can live with it.

Blob of red paint on the bit of the switch that is hidden when off. (Where ON is in your pic) until you splash out the price of a pint on a new one and maybe another 60p to get new backbox so you can mount it the right way up. 

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Originally, single MK fittings had the screws at top and bottom, while double sockets had four screws, two at top and two at bottom.   The singles and the doubles later changed to the present two screws at the sides. In the 1970's,  boxes for double sockets  were made with six threaded lugs to take sockets of either type,  and single boxes had  four lugs, top bottom left right.

Edited by Ronaldo47
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1 hour ago, Sea Dog said:

Thereby saving yourself the princely sum of less than a fiver, even if you buy a quality one like, say, a Crabtree. Those neons do fail and I'd say 25 years isn't a bad return from yours even if some do last even longer. Go on, splash out and be "mithered"! :D

 

Not just unmithered (a perfectly good word!) but can't be arsed either.

 

 

21 minutes ago, jonathanA said:

Blob of red paint on the bit of the switch that is hidden when off. (Where ON is in your pic) until you splash out the price of a pint on a new one and maybe another 60p to get new backbox so you can mount it the right way up. 

 

A fiver a pint? Not round here, pal!

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