Priority Switch Problems

Risteard81

2011 wrote: »

So you agree that 239 volts is not that unusual?

I wouldn't consider it to be particularly unusual. Although it was traditionally nominally 220V in the south and 230V in the north (and 240V in Britain).

John.G

My old (and still installed) 1972 Ferranti Ireland meter is stamped 60A 220V 50HZ.
I had > 240V here for years, up to last summer in fact, it's now 235/239V.

Sleeper12

2011 wrote:

Actually I was talking to Bruthal about it earlier on.

How rare a find do you think it is? I've seen lots of power showers with low reading but never an electric shower with basically no earth. Have I led a shelter life & like the toasted mouse on the top of the element should I have seen more of these over the years?

Sleeper12

John.G wrote:

My old (and still installed) 1972 Ferranti Ireland meter is stamped 60A 220V 50HZ. I had > 240V here for years, up to last summer in fact, it's now 235/239V.

I knew someone on the plumbing forum had 240v & a more powerful electric shower to boot

Bruthal

About the 1v measured at the shower L to E...

I posted a photo of multimeter setup to read amps earlier in the thread. One probe on socket phase.

Other into stream of water from sink tap. These things go unnoticed by most. Meaningless etc.

But anyway, 6.8ma flowed. So resistance was 32k ohms roughly in the stream. It varies depending on where the probe was in terms of distance from the tap or sink.

I also tested voltage. At socket L to N it was 234v. L to water stream it was 234v. Measure the exact same with an old moving coil meter, and we might see about 150v. Which one is correct?

So even though the water stream was like a non existant earth, the full supply voltage was seen.

It is very simple why this is, and demonstrates that seeing the full voltage is not proof of a good earth, only an indication.

Now to see 1v L to E suggests the earth point tested has voltage on it, rather than simply being a floating earth. Or the points tested where in fact N to E.

Try testing from phase to a length of floating wire, or a 100m coil still on the drum. A lot more than 1v will be seen with a digital meter.

Bruthal

Sleeper12 wrote: »

I knew someone on the plumbing forum had 240v & a more powerful electric shower to boot

I had 241v here yesterday. It will drop a few volts with the shower on.

Bruthal

Sleeper12 wrote: »

How rare a find do you think it is? I've seen lots of power showers with low reading but never an electric shower with basically no earth. Have I led a shelter life & like the toasted mouse on the top of the element should I have seen more of these over the years?

Voltage live to earth should read the same as neutral to earth on both.

Power shower installers just less likely to install proper earthing is the reason is it?

meercat

Shefwedfan wrote: »

I would need to be 100% and check but no, just the one shower

Cheers op
Your setup doesn’t seem to be correct. Again my advice is to get a competent rec out

Bruthal

On the faulty rcds. Socket circuit wiring is far more likely to have or develop earth faults than a shower circuit. Multiple outlet, items regularly plugged in and out, more prone to DIY, often steel boxes not properly bushed etc. So tripping rcds are likely due to circuit problems on socket circuits, the vast majority of what electricians will be called for.

Also with the devices often being rcbos on showers, the mcb part is now in the equation, going from fully loaded to off regularly. Electricians dismissing others regular observations like they are fantasy, without some consideration, is probably not the best approach.

Sleeper12

Bruthal wrote:

Power shower installers just less likely to install proper earthing is the reason is it?

My guess is that power showers are often installed by a plumber without REC. I assume that the bad earth's are from using small size cable and not securing them securely to the spur terminals or sometimes there are three or four sets of cables being fed from the immersion switch. Sloppy work in short.

I did come across one clever set up. Originally there was a low voltage shower with two core cable. Charging to 230V power shower they could not get an earth in so they wrapped a piece of copper wire around the earthed copper pipe going into the shower. It gave perfect reading but can see it being legal. All it would need is for a plumber to add a few inches of qualpex to the pipe in the attic and it would take the earth from the shower. A little knowledge can be dangerous

John.G

Bruthal wrote: »

On the faulty rcds. Socket circuit wiring is far more likely to have or develop earth faults than a shower circuit. Multiple outlet, items regularly plugged in and out, more prone to DIY, often steel boxes not properly bushed etc. So tripping rcds are likely due to circuit problems on socket circuits, the vast majority of what electricians will be called for.

Also with the devices often being rcbos on showers, the mcb part is now in the equation, going from fully loaded to off regularly. Electricians dismissing others regular observations like they are fantasy, without some consideration, is probably not the best approach.

And still and all, no requirement for a RCD on a cooker even though these are securely wired and now don't have a socket incorporated in the isolating switch. I have whole houe RCD (one) protection (including lighting) and have never had a cooker induced RCD trip, I wonder how much so called "nuisance" tripping would/do they really cause?.
The shower is separately RCBO protected.

Risteard81

John.G wrote: »

And still and all, no requirement for a RCD on a cooker even though these are securely wired and now don't have a socket incorporated in the isolating switch. I have whole houe RCD (one) protection (including lighting) and have never had a cooker induced RCD trip, I wonder how much so called "nuisance" tripping would/do they really cause?.
The shower is separately RCBO protected.

Every circuit in my house is protected by 30mA RCDs (including RCCBs and RCBOs). I've had no nuisance trips.

Bruthal

John.G wrote: »

And still and all, no requirement for a RCD on a cooker even though these are securely wired and now don't have a socket incorporated in the isolating switch. I have whole houe RCD (one) protection (including lighting) and have never had a cooker induced RCD trip, I wonder how much so called "nuisance" tripping would/do they really cause?.
The shower is separately RCBO protected.

Elements years ago may have had more earth path current but certainly modern ones don't. It's likely they will be a requirenent in time.

2011

Risteard81 wrote: »

Every circuit in my house is protected by 30mA RCDs (including RCCBs and RCBOs). I've had no nuisance trips.

Assuming the RCBO’s protect individual circuits rather than multiple circuits you have actually reduced chance of nuisance tripping. As such I would not expect you to have any issues. The more cabling connected to a circuit (assuming everything else is equal) the higher the leakage current (as no insulation is perfect).

The question is where do you stop?
Normally a risk assessment is used to select proportionate measures to mitigate the risk.

Why not upgrade to AFDDS ?
These will provide superior protection.

I know a particular site just off the M50 where they are so paranoid about sock risk that they make anyone opening a live panel wear full arc flash PPE. Some may argue that “you can’t be too careful”. My response it that they apply this rule to cabinets that only contain 24VDC instruments (from a limited source) so clearly they do not understand the “risk”.

Risteard81

2011 wrote: »

Assuming the RCBO’s protect individual circuits rather than multiple circuits you have actually reduced chance of nuisance tripping. As such I would not expect you to have any issues. The more cabling connected to a circuit (assuming everything else is equal) the higher the leakage current (as no insulation is perfect).

The question is where do you stop?
Normally a risk assessment is used to select proportionate measures to mitigate the risk.

Why not upgrade to AFDDS ?
These will provide superior protection.

I know a particular site just off the M50 where they are so paranoid about sock risk that they make anyone opening a live panel wear full arc flash PPE. Some may argue that “you can’t be too careful”. My response it that they apply this rule to cabinets that only contain 24VDC instruments (from a limited source) so clearly they do not understand the “risk”.

As I stated many are on RCCBs. Only my lighting circuits are on RCBOs to prevent sudden darkness if there was a fault.

As for AFDDs the reality is that they're simply not affordable yet. However I will fit a Type 2 SPD at some point.

Bruthal

2011 wrote: »

I know a particular site just off the M50 where they are so paranoid about sock risk that they make anyone opening a live panel wear full arc flash PPE. Some may argue that “you can’t be too careful”. My response it that they apply this rule to cabinets that only contain 24VDC instruments (from a limited source) so clearly they do not understand the “risk”.

Many of these rule makers are Google trained I'd say.

2011

Risteard81 wrote: »

As I stated many are on RCCBs.

Yes, but as some circuits are fed from RCBO's these are not on the RCCB's as such you have reduced the chances on nuisance tripping of the RCCB's

As you remove cabling (even "healthy" cabling) from RCCB's the leakage current reduces.

As for AFDDs the reality is that they're simply not affordable yet.

So that is the only reason not to install them?

However I will fit a Type 2 SPD at some point.

Will you install type 3 as well?

Tuco88

I find you will find differences in Voltages the closer to a substation/transformer you are. Not much within the ESBs tolerance band that is.

Bruthal

Tuco88 wrote: »

I find you will find differences in Voltages the closer to a substation/transformer you are. Not much within the ESBs tolerance band that is.

Yes that would be seen alright.


There are on load automatic tap changers which maintain a load based voltage range.

The time I was there, there were auto tap changers on the 10kv side of the 38kv transformers. They would be put into fixed tap mode if they were switching sections of 10kv line from one 38 station to another at which point the 2 38kv transformers would temporarily be in parallel. If left in auto mode during the parallel time, one transformer might start to take up to much of the load.

So these auto tap changers maintained the voltage range during different loadings according to the voltage.

Tuco88

Bruthal you must be a lecturer or something in the real world. �� wealth of knowledge.

Sleeper12

Tuco88 wrote:

Bruthal you must be a lecturer or something in the real world. wealth of knowledge.

Don't fall for it. He makes it up as he goes along

2011

Tuco88 wrote: »

Bruthal you must be a lecturer or something in the real world. �� wealth of knowledge.

Yes but he can’t work on the distribution board in his own home, too complicated

Bruthal

Tuco88 wrote: »

Bruthal you must be a lecturer or something in the real world. �� wealth of knowledge.

Its amazing what ye pick up arguing posting on here:)