Discuss Block of 200+ flats, eleven single channel hot water timers blown this week alone. in the UK Electrical Forum area at ElectriciansForums.net
Following MJ’s theme - MOVs do degrade each time they react to over voltages. It is not unknown for them to eventually suffer thermal runaway which is when their quiescent current rises over time, the MOV warms up, its resistance reduces, it passes more current, it warms up even more…until it cannot dissipate the heat quickly enough to its surroundings and it destructs. All of which can happen in the absence of any overvoltage.Don't think it's been asked, but did all eleven flats loose their timers at the same time, or was it cumulative over a period.
That is a good question but impossible to get a definitive answer as we don't know when they "went" only when the tenant discovered and reported them.Don't think it's been asked, but did all eleven flats loose their timers at the same time, or was it cumulative over a period.
But judging by the crazy disco lights I witnessed the issue is still ongoing and more will go.
Somebody needs to switch this lot off now.
Time to get the Megger out and 1000v dc @ the heater could be cable or heater.They are rated at 16A. The hot water cylinders are on a dedicated circuit off their own 16A MCB, isolated via a 20A double pole switch, length is a couple of meters.
Couldn't see a rating on the element but looking into that now.
Edit to add,
The elements are 3kW but looking at the plumbing I think they're on a central hot water system as there seems to be a coil on the cylinders.
I'm back there tonight two replace a couple and grab some more info.
Sorry wrong postTime to get the Megger out and 1000v dc @ the heater could be cable or heater.
Have never seen that happen, don't know what supply type is being used over here we use TTThere's some really clever people on this forum. I had to Google the electronic references, and, after reading them for a few minutes, I realised I was mentally debating tea or coffee to start the day (I went for tea).
So I can't help you there. But I will try to using my old favourite, Ockhams Razor ie go for the bleeding obvious.
Lights flickering, different flats affected, electronic gizmos feeling unwell (my knowledge of such things shines). And all about the same time.
It stinks of a neutral connection. It's the only common denominator. I can't see 11 Sangamo clocks packing up at the same time (Greenbrook, maybe..)
I was (un)lucky enough to see a neutral on a three phase supply go AWAL first hand ('tis a long story) and it is frightening. Voltage between phase and (apparent) neutral 270. Nope, 370. Nope 300. Nope 280 etc. Modular fittings jumping up in the suspended ceiling. Vending machines dying in agony.
Ok, this was for a period of minutes. Bit it's proof that the voltage goes crazy with a naughty neutral. It may be the case that your neutral was just a bit cheeky and went missing for a second or so.
One to watch out for.
Must say that have never seen that happen, the reason that said about the Megger iThere's some really clever people on this forum. I had to Google the electronic references, and, after reading them for a few minutes, I realised I was mentally debating tea or coffee to start the day (I went for tea).
So I can't help you there. But I will try to using my old favourite, Ockhams Razor ie go for the bleeding obvious.
Lights flickering, different flats affected, electronic gizmos feeling unwell (my knowledge of such things shines). And all about the same time.
It stinks of a neutral connection. It's the only common denominator. I can't see 11 Sangamo clocks packing up at the same time (Greenbrook, maybe..)
I was (un)lucky enough to see a neutral on a three phase supply go AWAL first hand ('tis a long story) and it is frightening. Voltage between phase and (apparent) neutral 270. Nope, 370. Nope 300. Nope 280 etc. Modular fittings jumping up in the suspended ceiling. Vending machines dying in agony.
Ok, this was for a period of minutes. Bit it's proof that the voltage goes crazy with a naughty neutral. It may be the case that your neutral was just a bit cheeky and went missing for a second or so.
One to watch out for.
The TT or TN supply type won't make any difference to equipment damage if you have an neutral fault on a 3-phase group of circuits. What is more likely to make a difference to the stats is the types of cable/joints used that might alter just how common such a fault is.Have never seen that happen, don't know what supply type is being used over here we use TT
over here we use TT
Final update.
First thing, we have plague in the house so this may be my last post. We have one positive test and I'm fairly sure I've got it now, did my test this morning.
Interestingly my missus who, is a double jabbed devotee, is in bed (three days now) with it after catching it on a camping trip.
What exactly does this vaccine do?
-*-
Anyway had a chat with the contact at the flats this morning and to be honest I'm befuddled by her explanation.
They have had the situation looked at and resolved. Apparently it was "some flat plugging in too many appliances and burnt out a fuse and some wires"
I find this highly implausible.
Any overload should have been dealt with by the OCPDs in the flats and not downstream. Unless the design of the installation was seriously FUBAR.
More likely they got the installers back in to check it over and they've tightened up their loose neutrals.
SKunk farm ? Anyway , i would like to know how their explanation would cause this issue (From a learning perspective )Final update.
First thing, we have plague in the house so this may be my last post. We have one positive test and I'm fairly sure I've got it now, did my test this morning.
Interestingly my missus who, is a double jabbed devotee, is in bed (three days now) with it after catching it on a camping trip.
What exactly does this vaccine do?
-*-
Anyway had a chat with the contact at the flats this morning and to be honest I'm befuddled by her explanation.
They have had the situation looked at and resolved. Apparently it was "some flat plugging in too many appliances and burnt out a fuse and some wires"
I find this highly implausible.
Any overload should have been dealt with by the OCPDs in the flats and not downstream. Unless the design of the installation was seriously FUBAR.
More likely they got the installers back in to check it over and they've tightened up their loose neutrals.
Reply to Block of 200+ flats, eleven single channel hot water timers blown this week alone. in the UK Electrical Forum area at ElectriciansForums.net
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