EEVblog 1651 - Home Electrical Switchboard UPGRADE

[EEVblog]

I'm finally upgrading the infamous rats nest home switchboard!
https://insightelectrical.com.au/

00:00 - A look at the old switchboard
03:29 - Single Phase
04:57 - Surge protection
05:28 - Old school ceramic fuses
06:04 - Inside the infamous Rats Nest!
08:29 - Simon from Insight Electrical
09:09 - Could you still do wiring like this?
10:04 - What's the plan?
11:12 - A look at the Hager surge protector
https://hager.com/au/products/download/product/asset/file/SURGE_BROCHURE_AUS_LOWRES.PDF
11:42 - Lightning strikes
12:19 - Current clamps and wiring looms
12:55 - Service neutral
13:16 - When did they stop uses fuses?
14:14 - Tesla brand DIN housing
15:36 - Why use Hager circuit breakers?
16:16 - Electrician toolbag and multimeter
https://www.kew-ltd.co.jp/en/products/detail/00036/
17:07 - Let's go!
17:53 - This is easy peasy
18:22 - What's this outdoor switchboard rubbish?
19:00 - What's your worst electrical shock?
19:41 - Troubleshooting bad wiring & dodgy brand circuit breakers
21:02 - I now have a Tesla brand switchboard
21:58 - It's looking good!
23:05 - Busses
24:10 - Asbestos panels?
24:47 - Service neutral and Level 1 vs Level 2 vs Level 3 electrical licenses
25:49 - Future upgrades?
26:46 - Average sized Australian home
27:34 - Wire strippers are for appentices!
27:47 - Made in China vs Made in Germany
28:09 - Why no bus bar for the neutral?
28:49 - How common is 3 phase in homes?
30:27 - Finished panel!
31:44 - A look at the final job next day

[flipper]

That’s a HORRIFIC mess. You’re an engineer, and you allowed that to be in your home? Try that here in England and you’d possibly end up in jail.

[EEVblog]

That’s a HORRIFIC mess. You’re an engineer, and you allowed that to be in your home?

Electrically it was completely safe and it was to code. It's just messy wiring due to half a dozen additions over the last 20 years.

[1fast4door]

Is this the first mention of the a new EEV clamp meter coming? Is there any info in what the new model will be?

[Brumby]

That’s a HORRIFIC mess. You’re an engineer, and you allowed that to be in your home?

Electrically it was completely safe and it was to code. It's just messy wiring due to half a dozen additions over the last 20 years.

As Dave said in the video, the "messy" look is very, very common.

[Brumby]

But .... what's this I see...?



HOW many strands are in that fuse ?!!!

[lowimpedance]

But .... what's this I see...?



HOW many strands are in that fuse ?!!!

That's because it would've been hard to get a fencing nail through that hole..

[Brumby]

 

[Monkeh]

The labeling is pretty awful. 'light light power power AC AC AC' - okay, which one? Just flip a few and see? Is it even really known where any of those go?

Why the mix of single and double pole devices?

[EEVblog]

Is this the first mention of the a new EEV clamp meter coming? Is there any info in what the new model will be?

Not a clamp, BM2257

[WIMPy]

Am I the only one who sees a little issue with the new setup?

The 63A "main switch" surely looked a lot like a MCB. So I looked up the part number. And surely it actually is a 63A MCB mit C-characteristic.

So whenever you get a short circuit anywhere, not only would the MCB for that circuit trip, but the main 63A one as well.
That's not good.
That should be replaced by a simple isolating switch. Or if there's some reason for it to be a circuit breaker, it should have E-characteristic.
But as there's the incoming main fuse already, I see no need.

[BradC]

So whenever you get a short circuit anywhere, not only would the MCB for that circuit trip, but the main 63A one as well.

Not quite. Look up "discrimination" between electrical protective devices.

This was the first link that came up which describes it in laymans terms : https://www.tlc-direct.co.uk/Book/3.8.6.htm

This is something we bump up against regularly when doing critical service reviews. Stacked protective devices are absolutely common and done with adequate attention to ratings and curves provide the correct device fault sequencing.

[Monkeh]

So whenever you get a short circuit anywhere, not only would the MCB for that circuit trip, but the main 63A one as well.

Not quite. Look up "discrimination" between electrical protective devices.

This was the first link that came up which describes it in laymans terms : https://www.tlc-direct.co.uk/Book/3.8.6.htm

This is something we bump up against regularly when doing critical service reviews. Stacked protective devices are absolutely common and done with adequate attention to ratings and curves provide the correct device fault sequencing.

Except such attention hasn't been given. Those are all C curve, which means a genuine short is just as likely to take out the C63 as any other device.

[BradC]

Except such attention hasn't been given. Those are all C curve, which means a genuine short is just as likely to take out the C63 as any other device.

They don't have to be different curve devices, they just need to ensure the trip characteristics don't intersect at the likely fault currents.
A simple rule of thumb is triples. In Australia, common GPO circuits can use up to a 20A protection device (still commonly 16A). With a 63A main switch, it's highly likely the fault current available to a 20A GPO circuit will trip the 20A device before the 63A device gets out of bed even if they both have the same curve.

If we were talking about a house wired in superconductors, then your point might be valid. But the impedance of the circuits reduces the theoretical maximum fault current. In practice it works.
Regardless, behind the 63A MCB is going to be a set of primary protection devices (HRC fuses commonly) between the meter and the street, so there's another variable to consider.

[WIMPy]

So whenever you get a short circuit anywhere, not only would the MCB for that circuit trip, but the main 63A one as well.

Not quite. Look up "discrimination" between electrical protective devices.

As has already been pointed out, there isn't any in this case.

Stacked protective devices are absolutely common and done with adequate attention to ratings and curves provide the correct device fault sequencing.

I was specifically talking about short circuits.
Even if the individual circuits were B types and the main breaker was of type D, it would still be an issue.
It would only help with a moderate overload over a longer period of time where the thermal trigger responds differently.

With a short circuit it's about the magnetic trigger and that's the same on B, C and D types.
That's why I recommended the E type, which doesn't have a magnetic trigger.

And it's not really about either of them tripping at random. They will almost certainly both trip simultaneously.

[Monkeh]

Except such attention hasn't been given. Those are all C curve, which means a genuine short is just as likely to take out the C63 as any other device.

They don't have to be different curve devices, they just need to ensure the trip characteristics don't intersect at the likely fault currents.

This is all well and good if your PSC/PFC is small. This may well not be the case for one of those (needlessly) C32 devices. Did you see PSC or PFC measured? I didn't.

The majority of events may well not reach the full fault current and thereby not magnetically operate the C63 device, but that's not designing for discrimination, that's chance.

[EEVblog]

Except such attention hasn't been given. Those are all C curve, which means a genuine short is just as likely to take out the C63 as any other device.

They don't have to be different curve devices, they just need to ensure the trip characteristics don't intersect at the likely fault currents.
A simple rule of thumb is triples. In Australia, common GPO circuits can use up to a 20A protection device (still commonly 16A). With a 63A main switch, it's highly likely the fault current available to a 20A GPO circuit will trip the 20A device before the 63A device gets out of bed even if they both have the same curve.

If we were talking about a house wired in superconductors, then your point might be valid. But the impedance of the circuits reduces the theoretical maximum fault current. In practice it works.
Regardless, behind the 63A MCB is going to be a set of primary protection devices (HRC fuses commonly) between the meter and the street, so there's another variable to consider.

Without having actually tested it, this would be what I would expect.

[Monkeh]

Without having actually tested it

And there's the crux of the issue.

Was any real testing done? Sure, someone may have walked around with a socket tester and roughly verified polarity and the vague presence of an earth, but were any actual tests done? Are the protective devices known to operate?

[EEVblog]

Was any real testing done? Sure, someone may have walked around with a socket tester and roughly verified polarity and the vague presence of an earth, but were any actual tests done? Are the protective devices known to operate?

I had to leave early so did not get to see what testing they did, apart from another guy who went inside with a tester.
I am not the least bit concerned about shorts. There are literally three inline fuses of various types, and they are a top name brand, and I'm on BradC with this that in practice it won't be a problem.
You are making a mountain out of a mole hill.
In my 20 years in the house I have never ever had a short happen. The only faults have been product earth leakage issues that have tripped the RCD.

You are the one that actually recommended removing one of those three protection devices and replacing with a switch. No thanks, I'll take the extra 63A breaker. I don't care that in the extremely remote possibility that there is a short, that it trips the entire house. It's a non issue.

[Monkeh]

I am not the least bit concerned about shorts. There are literally three inline fuses of various types, and they are a top name brand, and I'm on BradC with this that in practice it won't be a problem.

You are perhaps not understanding the issue being discussed.

You are the one that actually recommended removing one of those three protection devices and replacing with a switch.

Or, indeed, tracking the conversation accurately. I haven't made any sort of recommendation. I'm also not scared of 240V and yet reassured by safety systems put together by rote and "she'll be right" rather than engineering.

I don't care that in the extremely remote possibility that there is a short, that it trips the entire house. It's a non issue.

Fine. Having been the one having to make my way downstairs and turn the power back on in darkness because of lack of discrimination, I do.

It's your house, after all. But funnily enough, when you post videos people will watch them and raise questions and criticisms. You needn't take them personally.. especially when you didn't design or install any of it. You're seeing a mountain when people are discussing the mole hill.

[EEVblog]

You are the one that actually recommended removing one of those three protection devices and replacing with a switch.

Or, indeed, tracking the conversation accurately. I haven't made any sort of recommendation.

Sorry, that was Wimpy.

It's your house, after all. But funnily enough, when you post videos people will watch them and raise questions and criticisms. You needn't take them personally.. especially when you didn't design or install any of it. You're seeing a mountain when people are discussing the mole hill.

That fine. But I simply don't think it's going to be a problem as claimed. I think it will work in practice as BradC has mentioned.

[Monkeh]

But I simply don't think it's going to be a problem as claimed. I think it will work in practice as BradC has mentioned.

Probably will be. I, and probably WIMPy, am approaching this from the perspective of the engineering of a safety system deployed billions of times over. "Usually okay" isn't reassuring to me in that context. Nor is "usually just an inconvenience".

You could test the discrimination in practice if you feel adventurous.. Or perhaps have Mehdi visit?

[BradC]

That fine. But I simply don't think it's going to be a problem as claimed. I think it will work in practice as BradC has mentioned.

Easy way to check (and yes, we do this in critical server rooms when demonstrating to clients they have the discrimination wrong after a theoretical review) is get a standard 3 pin plug and wire the active and neutral across a decent sized switch. "flick, boom". What trips?

Honestly, dead shorts across a GPO are pretty rare but they do happen. When I was a lot younger I was re-stringing a guitar on my desk. One of the strings flicked up and came down across the pins of a plug that was slightly dislocated from the socket shorting active and neutral. It made a mess and tripped the anticipated breaker rather than the main. These days that wouldn't happen because the plugs all have insulation on their pins up to the termination point.

One of my other fun tricks is to wire a 16A fuse wire between active a neutral on a 3 pin plug, plug the plug into an extension cord and switch it on (at a distance). Sometimes the empirical tests can be quite illustrative.

[Monkeh]

That fine. But I simply don't think it's going to be a problem as claimed. I think it will work in practice as BradC has mentioned.

Easy way to check (and yes, we do this in critical server rooms when demonstrating to clients they have the discrimination wrong after a theoretical review) is get a standard 3 pin plug and wire the active and neutral across a decent sized switch. "flick, boom". What trips?

Bearing in mind the results can be drastically different depending on whether the outlet is on the other side of the house or the other side of the wall. The C32s are of markedly more concern than C16s, being closer to the magnetic characteristics (technically, they could be identical) and much lower impedance circuits.

It's probably worth pointing out that I, at least, am from a country with a ready selection of TN-C-S, TN-S, TT, and hybrid shudder installations. It can be hazardous to assume both function and discrimination of protective devices.

[EEVblog]

Probably will be. I, and probably WIMPy, am approaching this from the perspective of the engineering of a safety system deployed billions of times over. "Usually okay" isn't reassuring to me in that context. Nor is "usually just an inconvenience".
You could test the discrimination in practice if you feel adventurous.. Or perhaps have Mehdi visit?

Even if I did that, and only the 20A tripped, you'd still argue it's engineered wrong. So what's the point?
All I care about is that is the wiring in my house is protected (which is the sole job of a fuse/breaker). It's in fact safer than it was before with just the 63A switch and the main street fuse.