Distribution panel question

[Dr Bob]

Advice needed on how our distribution panel works. See pic below.

A month ago, the switch/fuse controlling the water pump supply 'tripped' ie no power to the pump and the rocker switch was illuminated. I had expected that the 'fuse', ie the black button to the right of the switch (a 'fuse' is shown bottom right – held by SWMBO!) would have 'popped out' and needing to be reset but that was not the case. I swapped the 'fuse' unit with one of the unused ones on the panel and the water pump worked as normal.

Today, the water pump started to play up (lets discuss that later) and the power to it went off and the switch was illuminated again. I swapped out the pump with a new one – I was expecting it to die – but with the new one in, the rocker switch was still illuminated and no power. Again I swapped the 'fuse' unit with an unused one and connected it up. The switch was illuminated but after about a minute it started to work again and the new pump is now fine.

My question therefore is about how the rocker switch and 'fuse' unit work. The black buttons on the fuse units never seem to 'pop' out – so are these fuses that can be reset? What controls the illumination of the rocker switch? Is it a temperature thing? I guess the water pump today was about to die and overloaded the panel switch but not sure how the panel protects too high currents.

The panel and switches are 2002 vintage.

 

[GUMPY]

Normally the fuse will be in parallel with the indicator so fuse ok the indicator is shorted out so stays off. Fuse blown indicator lights up but wont pass enough current to operate pump. 

ETA they look like thermal trips,  push to reset.

ETA2 Google joemex pe74 and you will get data sheet

Edited September 23, 2017 by Loddon

[Dr Bob]

3 minutes ago, Loddon said:

Normally the fuse will be in parallel with the indicator so fuse ok the indicator is shorted out so stays off. Fuse blown indicator lights up but wont pass enough current to operate pump. 

Sorry but I am being a bit thick here. Not sure what you are saying.

The fuse and indicator are in parallel -ok. How does the indicator short out and so stays off while the fuse is still working?

I assume the illuminated switch is the 'fuse blown indicator' - but the black button hasnt popped out so the fuse hasnt blown?  What am I getting wrong?

 

[WotEver]

6 minutes ago, Dr Bob said:

Sorry but I am being a bit thick here. Not sure what you are saying.

The fuse and indicator are in parallel -ok. How does the indicator short out and so stays off while the fuse is still working?

I assume the illuminated switch is the 'fuse blown indicator' - but the black button hasnt popped out so the fuse hasnt blown?  What am I getting wrong?

 

The breaker has broken, because there was no power to the pump. Because the breaker is open circuit the lamp in the switch lit up. 

Why the breaker hasn’t actually popped out is a bit of a mystery unless... there is a dodgy connection to the breaker and the process of swapping it over re-makes the connection temporarily. 

Or maybe it’s not really popped out very far and just needs a good push?

10 minutes ago, Dr Bob said:

How does the indicator short out and so stays off while the fuse is still working?

Think of the breaker as a switch. If you connect an indicator across the switch (in parallel with it) then when the switch is closed the indicator will have no voltage across it and will not illuminate. When the breaker pops the ‘switch’ is open, so now the indicator has voltage across it and lights up. 

Make sense?

[WotEver]

Or possibly you have nothing more mysterious than a couple of dodgy breakers. 

[Dr Bob]

7 minutes ago, WotEver said:

The breaker has broken, because there was no power to the pump. Because the breaker is open circuit the lamp in the switch lit up. 

Why the breaker hasn’t actually popped out is a bit of a mystery unless... there is a dodgy connection to the breaker and the process of swapping it over re-makes the connection temporarily. 

Or maybe it’s not really popped out very far and just needs a good push?

Think of the breaker as a switch. If you connect an indicator across the switch (in parallel with it) then when the switch is closed the indicator will have no voltage across it and will not illuminate. When the breaker pops the ‘switch’ is open, so now the indicator has voltage across it and lights up. 

Make sense?

Thanks for that. I think I understand. Let me try and get this right.

The breaker 'pops' when the current gets too high and hence the black button comes out and the switch indicator lights up as it is in parralell, and the power to the device goes off. That is what I originally thought, however the black button never seems to pop out. This has happened on 2 different breakers. I bought a new one but must have put it on one of the other circuits. If the black button does not pop out, how can you reset it? Do these breakers have a habit of not popping out or failing with age? Is there anyway of testing the breakers to see if they work? Sounds like I may need to buy a few new ones.

[WotEver]

1 minute ago, Dr Bob said:

Do these breakers have a habit of not popping out or failing with age?

Not that I’m specifically aware of, but I have no experience of this particular type. It’s certainly possible for them to simply fail and not pop, particularly if it’s been running close to its limit for an extended period. It’s a mechanical device after all  

To test for continuity, just stick a multimeter across the terminals in either a low resistance or diode test or continuity setting and see if it’s open circuit or not. To test its operation would require you to attach a load of about three times its rated current and it should pop within 10 seconds. 

http://www.joemexcn.com/upfiles/2006060914235899319.pdf

[Dr Bob]

4 minutes ago, WotEver said:

Not that I’m specifically aware of, but I have no experience of this particular type. It’s certainly possible for them to simply fail and not pop, particularly if it’s been running close to its limit for an extended period. It’s a mechanical device after all  

To test for continuity, just stick a multimeter across the terminals in either a low resistance or diode test or continuity setting and see if it’s open circuit or not. To test its operation would require you to attach a load of about three times its rated current and it should pop within 10 seconds. 

http://www.joemexcn.com/upfiles/2006060914235899319.pdf

Thanks for that link. I will have a look. I was meaning to go to their website but you beat me to it. I will post a new thread on the water pump problem tomorrow!

[WotEver]

This actually takes me back umpty-ump years to when I worked on flight simulators. Early days of computers but we could enter a specific address to pop any breaker on any panel on the flight deck. To make life easy, the breakers that we used were all 1A and we’d pass 10A through them via a large wirewound resistor to make them pop nice and vigorously. They all had stickers on them to indicate their power so we just had a big box of those labels to ensure that each breaker appeared to be the correct rating. Where it became interesting was with the larger breakers, like 50A. They were a physically bigger beast altogether so we had to manufacture a weedy little 1A breaker with a hefty great 50A ‘popper’ just to make it look authentic on the flight deck. 

[Eeyore]

3 hours ago, Dr Bob said:

Thanks for that. I think I understand. Let me try and get this right.

The breaker 'pops' when the current gets too high and hence the black button comes out and the switch indicator lights up as it is in parralell, and the power to the device goes off. That is what I originally thought, however the black button never seems to pop out. This has happened on 2 different breakers. I bought a new one but must have put it on one of the other circuits. If the black button does not pop out, how can you reset it? Do these breakers have a habit of not popping out or failing with age? Is there anyway of testing the breakers to see if they work? Sounds like I may need to buy a few new ones.

My 1996 vintage panel has had similar failures (button did not "pop" out) with these breakers on water pump and shower pump circuits. Probably something to do with using them on motor circuits. I fitted a higher rated breaker (but still below the current capacity of the cable) which seems ok so far.

[Dr Bob]

16 hours ago, Eeyore said:

My 1996 vintage panel has had similar failures (button did not "pop" out) with these breakers on water pump and shower pump circuits. Probably something to do with using them on motor circuits. I fitted a higher rated breaker (but still below the current capacity of the cable) which seems ok so far.

Thanks Eeyore. Good to hear it is not only my buttons that dont pop. Any ideas why they would not work with motor circuits? I think I will buy a couple of new ones.

[WotEver]

40 minutes ago, Dr Bob said:

Any ideas why they would not work with motor circuits?

Possibly due to the start-up surge. However, I doubt that’s the case, I think it more likely that it’s simply fatigue from continuous running close to the rating. 

[Dr Bob]

Just now, WotEver said:

Possibly due to the start-up surge. However, I doubt that’s the case, I think it more likely that it’s simply fatigue from continuous running close to the rating. 

Yes, sounds plausible. Maybe I will look at getting some 20A ones for the water pump.