I tend to move the L to the earth bar these days - saves things going bang!
Embarrassment avoidance today .
- Thread starter Evans Electric
- Start date
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30 + years back I installed a 100kKVR capacitor, the end of the cable run was through a 2” elbow in to the cable box. Testing a PFC capacitor is a bit hit and miss so just switch on. Everything was fine until the great white chief showed up and asked how I’d got a 70mm² 3c through the elbow. He kicked it and it exploded.
The next day I was busy with a jackhammer to get a good route to the cable box. It was what I wanted to do in the first place.
Anything can happen under load after switch on. Forgetting to crimp a 185mm² core on a PLIC cable took some explaining.
It happens to all of us, a laps of concentration and you have to find a reason (excuse).
The next day I was busy with a jackhammer to get a good route to the cable box. It was what I wanted to do in the first place.
Anything can happen under load after switch on. Forgetting to crimp a 185mm² core on a PLIC cable took some explaining.
It happens to all of us, a laps of concentration and you have to find a reason (excuse).
Risteard
Senior Member
There is a school of thought that says the live to earth link should be placed at the far end of the circuit. If you consider a circuit with two faults on it 1) The CPC is open circuit. and 2) Downstream of the break its shorted to phase.
If you were to apply the link at the board, and then test at the far end of the circuit, you'd see continuity through the short, you'd see continuity even with no link at the board, but we don't generally connect the meter with it reading open, go and fit the link, then go back and check meter.... When we came to to the insulation test, because of the break in cpc before fault, we'd also see clear, unless there was a reasonable path from class one equipment to the phycial ground, but thats no going to be the case in a lot of situations, such as class 1 flouro battens on a wood and plasterboard ceiling. You've got an R1R2 and an insulation test, must be time to switch on and go and get an earth loop then...
If the short was first, and the break after it, and you were applying the link at the far end, testing at the board, then on R1R2 yes, you'd see an incorrect result through the short , but then you'd see the short on IR. You'd then see the open CPC when you want back and repeated the R1R2 test after clearing the short (as one should...)
A few years ago now, I changed a pullcord in a statsic caravan, it was one of those, "just pop there and sort this out on your way out will ya?". One T/E at pullswitch as normal. Disconnect it, new one up, went to fill out the minor works, board isolated, move live into earth bar, quick R1R2 at the pull switch, note it down, all good, back to board, insulation all clear (LN together tested to earth). Reconnect and switch on, go to grab a quick Zs, not getting anything, but I've got an R1R2 and I've got a loop at the board that I checked while I was in there, so how come there is no earth here? Look a little closer, it was a two way set up with anonother pullcord out of sight. The CPC had used as a strapper, I'd not noticed when I took the old one down that it was two way and had just fitted a 1way and put the cpc in the earth parking terminal. Now luckily it was only class 2 equipment that I'd connected an earth core that was actually live to, but it shows how you can believe you have proven something, when in actual fact you've been mislead by things not being how they should be
If you were to apply the link at the board, and then test at the far end of the circuit, you'd see continuity through the short, you'd see continuity even with no link at the board, but we don't generally connect the meter with it reading open, go and fit the link, then go back and check meter.... When we came to to the insulation test, because of the break in cpc before fault, we'd also see clear, unless there was a reasonable path from class one equipment to the phycial ground, but thats no going to be the case in a lot of situations, such as class 1 flouro battens on a wood and plasterboard ceiling. You've got an R1R2 and an insulation test, must be time to switch on and go and get an earth loop then...
If the short was first, and the break after it, and you were applying the link at the far end, testing at the board, then on R1R2 yes, you'd see an incorrect result through the short , but then you'd see the short on IR. You'd then see the open CPC when you want back and repeated the R1R2 test after clearing the short (as one should...)
A few years ago now, I changed a pullcord in a statsic caravan, it was one of those, "just pop there and sort this out on your way out will ya?". One T/E at pullswitch as normal. Disconnect it, new one up, went to fill out the minor works, board isolated, move live into earth bar, quick R1R2 at the pull switch, note it down, all good, back to board, insulation all clear (LN together tested to earth). Reconnect and switch on, go to grab a quick Zs, not getting anything, but I've got an R1R2 and I've got a loop at the board that I checked while I was in there, so how come there is no earth here? Look a little closer, it was a two way set up with anonother pullcord out of sight. The CPC had used as a strapper, I'd not noticed when I took the old one down that it was two way and had just fitted a 1way and put the cpc in the earth parking terminal. Now luckily it was only class 2 equipment that I'd connected an earth core that was actually live to, but it shows how you can believe you have proven something, when in actual fact you've been mislead by things not being how they should be
