Ask an Electrician anything...

Ask an Electrician anything...

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ruggedscotty

Original Poster:

5,606 posts

208 months

Thursday 23rd March 2023
quotequote all
dhutch said:
ruggedscotty said:
Had a think about this.... If its just PC's then surely a cheap double conversion would suffice, and does it need to be a UPS ?

https://www.criticalpowersupplies.co.uk/p/tripp-li...

How about.... the wild card...

12 or 24 v power supply - to a battery. then an invertor to 220v. this invertor supplying a dedicated circuit and distribution out to the computer systems.
Isn't that pretty much what's inside a double conversation UPS unit?
Indeed the principle is the same - you can get into a fiat and drive to London or a Maybach and be driven....

horses for courses.

The double conversion UPS can be expensive if going for a lot of load, and as Im not to sure of the load that was being mentioned I gave up two ideas.

Double conversion on the UPS is running most of the load through the power supply and having only the power dips being supported through the battery... With the other system mentioned.... you could charge the batteries the whole time and use the batteries to power the invertor when required.

it depends on the overall set up, and using the battery side of things it could be set up as a demonstration of alternative power.... what could be used to charge the battery ? solar power water wheel... you get the drift, and as its a techy place they actually might like the idea of an interactive multi source power system....

could become an exhibit in its own right. look at us were using natural resources to power our PC's.... win win if you ask me

AW10

4,422 posts

248 months

Thursday 23rd March 2023
quotequote all
I have a detached garage that is fed from a 50A supply from the house through a dedicated fused isolator. In the garage there’s a consumer unit with RCBOs for the ring main and lights and a 20A circuit feeding a 32A commando socket. Is connecting a 2nd 32A commando socket to that circuit allowed? The consumers (2 lifts) are rated at 16A and 20A and would never both be operated at once. Is this an allowable example of diversity? It would save running an extra circuit.

dhutch

14,198 posts

196 months

Thursday 23rd March 2023
quotequote all
AW10 said:
I have a detached garage that is fed from a 50A supply from the house through a dedicated fused isolator. In the garage there’s a consumer unit with RCBOs for the ring main and lights and a 20A circuit feeding a 32A commando socket. Is connecting a 2nd 32A commando socket to that circuit allowed? The consumers (2 lifts) are rated at 16A and 20A and would never both be operated at once. Is this an allowable example of diversity? It would save running an extra circuit.
I'm not a spark, and it might not be what you would do in an ideal situation, but assuming everything down stream is able to be protected by a 20A breaker (ie, the cable to the second socket is a suitable gauge) I believe it is allowed, just like having a radial of ten 13A sockets off a 20A breaker.

Which if two lifts is the new one?

ruggedscotty

Original Poster:

5,606 posts

208 months

Thursday 23rd March 2023
quotequote all
AW10 said:
I have a detached garage that is fed from a 50A supply from the house through a dedicated fused isolator. In the garage there’s a consumer unit with RCBOs for the ring main and lights and a 20A circuit feeding a 32A commando socket. Is connecting a 2nd 32A commando socket to that circuit allowed? The consumers (2 lifts) are rated at 16A and 20A and would never both be operated at once. Is this an allowable example of diversity? It would save running an extra circuit.
I know what your saying and yes if the breakers are all rated with the apropriate ratings type and the circuit has been tested and has the right loop values etc. wee bit required to ensure your meeting the requirements. but it would be fine. worst case run both at the same time your breaker would simply trip.

https://www.niceic.com/Niceic.com/media/Pocket-Gui...

As its outwith the house Id be checking and ensuring that ther loops are compliant as by nature you will have more cable between the origin and point of use to consider.

The danger here is that if you dont use the right breaker for the loop values then you wont achieve disconnection times and you could over stress your cables. which you dont want to do.


Edited by ruggedscotty on Thursday 23 March 23:01

Gary C

12,315 posts

178 months

Friday 24th March 2023
quotequote all
Ideal would be a proper digital UPS. 240 to Charger, DC then to a digital inverter so a perfect sine wave.

But far to expensive.

A couple of level 2 surge arrestors fitted.

The failure of the PET was a ceramic disk capacitor. First one of those to fail.

_-XXXX-_

10,288 posts

204 months

Friday 24th March 2023
quotequote all
Jesus Christ. Only on here could this happen. Mains has ALWAYS had spikes, dips, brown outs, frequency fluctuation. Your old computers aren't dying because of any of that. They're old, I've spent hours fixing old arcade game PCBs. RAM, ROM, logic etc..they all die sooner or later. You could run them off batteries via angle hair twisted with 1000% pure copper and they'd still die.

Gary C

12,315 posts

178 months

Saturday 25th March 2023
quotequote all
_-XXXX-_ said:
Jesus Christ. Only on here could this happen. Mains has ALWAYS had spikes, dips, brown outs, frequency fluctuation. Your old computers aren't dying because of any of that. They're old, I've spent hours fixing old arcade game PCBs. RAM, ROM, logic etc..they all die sooner or later. You could run them off batteries via angle hair twisted with 1000% pure copper and they'd still die.
Sorry

Only worked in the electricity generating industry for 40 years, got a degree in electronic engineering, and many years maintaining (and programming) 70's reactor control computers.

So I bow to your expertise

The Mill has some very large inductive loads and switching transients can cause significant local spikes.

NMOS chips are no where near as susceptible as CMOS but still, I want to ensure they have the best possible environment.

Puzzles

1,784 posts

110 months

Saturday 25th March 2023
quotequote all
I had an outside socket installed should I have received any sign off paperwork?

ruggedscotty

Original Poster:

5,606 posts

208 months

Saturday 25th March 2023
quotequote all
Puzzles said:
I had an outside socket installed should I have received any sign off paperwork?
an INSTALLATION CERTIFICATE for ALL electrical work should be provided (but not always supplied!). The electrician certifies that the work he has done complies with BS7671. This is the case now, and has been the case for many years.

In 2005, the UK government decided that electrical work should be covered by Building Regulations. They produced a STATUTORY INSTRUMENT (Law) that basically says all electrical work must be done safely. That’s all it says.
To make sure everybody understood what “safely” means they produced a guide (Approved Document) that goes into lots of stuff. There are two key areas that affect this thread:
1. It says that work should be done to a recognised standard, and notes BS7671 as they one they rather prefer.
2. It says that it’s ok to do some electrical work yourself but that the more tricky stuff must be notified* and approved by the Local Authority’s Building Control. So that the LABC don’t have to visit to approve every involved installation they make it difficult and expensive for the DIYer who wants to rewire his own house. So they set up a process so that electricians who are registered with one of the competent person schemes (NICEIC,etc) can contact their scheme and tell them that they (the electrician) have rewired Mrs Smith’s house. This is done electronically and the LABC get an electronic notification of the fact. Mrs Smith gets a CERTIFICATION OF COMPLETION that the work done complies with parts 4 & 7 of the building regulations (nobody knows what these are).
So that’s it. NO PART P CERTIFICATE.

  • things that need notification:-
Back in 2005, in the Approved Document, much electrical work required notification. These included new circuits, consumer units, work in special locations such as kitchens, bathrooms, outside, etc. In the ensuing years, much of this has been stripped out (pity IMO). Kitchens and outside are no longer notifiable in England. Other colonies of England have slightly differing rules.

ruggedscotty

Original Poster:

5,606 posts

208 months

Saturday 25th March 2023
quotequote all
_-XXXX-_ said:
Jesus Christ. Only on here could this happen. Mains has ALWAYS had spikes, dips, brown outs, frequency fluctuation. Your old computers aren't dying because of any of that. They're old, I've spent hours fixing old arcade game PCBs. RAM, ROM, logic etc..they all die sooner or later. You could run them off batteries via angle hair twisted with 1000% pure copper and they'd still die.
Many years of working in many electrical installations. I can assure you that mains borne issues can and do have a negative effect on electronics, hence the need to line conditioners and the like.

Is one of the reasons that the requirements for electrical installations now specify the installation of surge protectors. the IET with many members and tyears of experiance to back it up will disagree with your statement on compluters....

have a read

https://electrical-assistance.co.uk/spd-regulation...

oh and your welcome..

OutInTheShed

7,368 posts

25 months

Saturday 25th March 2023
quotequote all
Gary C said:
_-XXXX-_ said:
Jesus Christ. Only on here could this happen. Mains has ALWAYS had spikes, dips, brown outs, frequency fluctuation. Your old computers aren't dying because of any of that. They're old, I've spent hours fixing old arcade game PCBs. RAM, ROM, logic etc..they all die sooner or later. You could run them off batteries via angle hair twisted with 1000% pure copper and they'd still die.
Sorry

Only worked in the electricity generating industry for 40 years, got a degree in electronic engineering, and many years maintaining (and programming) 70's reactor control computers.

So I bow to your expertise

The Mill has some very large inductive loads and switching transients can cause significant local spikes.

NMOS chips are no where near as susceptible as CMOS but still, I want to ensure they have the best possible environment.
Mains has always been 'dirty' but it's possibly dirtier now than it used to be?
There are more switch mode power supplies and such like.
OTOH, there are less people running hundreds of watts of lights through thyristor dimmers.

But also it's possible that the power supplies in old kit are not as good at filtering the mains as they used to be when new?
Electrolytic capacitors can lose capacity as they age.
Other parts can degrade with age.

Even the digital ICs of the computer itself will age. Semiconductors do 'wear out' with time and temperature.

When I started work, things like the BBC Micro and the Commodore Pet were beginning to become popular and used a lot in colleges and schools. When they drifted from college to industry, they were unreliable and I recall they were either cossetted with filtered power supplies and all that, or replaced with proper expensive stuff from HP.

dhutch

14,198 posts

196 months

Saturday 25th March 2023
quotequote all
ruggedscotty said:
Puzzles said:
I had an outside socket installed should I have received any sign off paperwork?
an INSTALLATION CERTIFICATE for ALL electrical work should be provided (but not always supplied!). The electrician certifies that the work he has done complies with BS7671. This is the case now, and has been the case for many years.

In 2005, the UK government decided that electrical work should be covered by Building Regulations. They produced a STATUTORY INSTRUMENT (Law) that basically says all electrical work must be done safely. That’s all it says.
To make sure everybody understood what “safely” means they produced a guide (Approved Document) that goes into lots of stuff. There are two key areas that affect this thread:
1. It says that work should be done to a recognised standard, and notes BS7671 as they one they rather prefer.
2. It says that it’s ok to do some electrical work yourself but that the more tricky stuff must be notified* and approved by the Local Authority’s Building Control. So that the LABC don’t have to visit to approve every involved installation they make it difficult and expensive for the DIYer who wants to rewire his own house. So they set up a process so that electricians who are registered with one of the competent person schemes (NICEIC,etc) can contact their scheme and tell them that they (the electrician) have rewired Mrs Smith’s house. This is done electronically and the LABC get an electronic notification of the fact. Mrs Smith gets a CERTIFICATION OF COMPLETION that the work done complies with parts 4 & 7 of the building regulations (nobody knows what these are).
So that’s it. NO PART P CERTIFICATE.

  • things that need notification:-
Back in 2005, in the Approved Document, much electrical work required notification. These included new circuits, consumer units, work in special locations such as kitchens, bathrooms, outside, etc. In the ensuing years, much of this has been stripped out (pity IMO). Kitchens and outside are no longer notifiable in England. Other colonies of England have slightly differing rules.
Ie, because it's an outdoor socket, yes.

Assuming it was an electrician who did it, and they followed rules.

Equally I've see "outdoor socket for £20" posts on Facebook alongside the far more prolific outside tap posts. And I expect they come with no paperwork and cash in hand to boot.

dhutch

14,198 posts

196 months

Saturday 25th March 2023
quotequote all
OutInTheShed said:
Mains has always been 'dirty' but it's possibly dirtier now than it used to be?
There are more switch mode power supplies and such like.
OTOH, there are less people running hundreds of watts of lights through thyristor dimmers.

But also it's possible that the power supplies in old kit are not as good at filtering the mains as they used to be when new?
Electrolytic capacitors can lose capacity as they age.
Other parts can degrade with age.

Even the digital ICs of the computer itself will age. Semiconductors do 'wear out' with time and temperature.

When I started work, things like the BBC Micro and the Commodore Pet were beginning to become popular and used a lot in colleges and schools. When they drifted from college to industry, they were unreliable and I recall they were either cossetted with filtered power supplies and all that, or replaced with proper expensive stuff from HP.
Interesting thoughts, especially about BBC Micros in industrial. Which if there is a machine shop on the floor below is effectively what we have here.

Puzzles

1,784 posts

110 months

Saturday 25th March 2023
quotequote all
dhutch said:
Ie, because it's an outdoor socket, yes.

Assuming it was an electrician who did it, and they followed rules.

Equally I've see "outdoor socket for £20" posts on Facebook alongside the far more prolific outside tap posts. And I expect they come with no paperwork and cash in hand to boot.
No a local reputable company NICEIC registered.

OutInTheShed

7,368 posts

25 months

Saturday 25th March 2023
quotequote all
dhutch said:
Interesting thoughts, especially about BBC Micros in industrial. Which if there is a machine shop on the floor below is effectively what we have here.
These days, it's probably got a switch mode power supply which gives a little isolation from mains spikes, and a little more protection on the interfaces?
That said, we were pretty good at blowing things up back then, 'no pacemakers beyond this point' and all that.

Gary C

12,315 posts

178 months

Saturday 25th March 2023
quotequote all
OutInTheShed said:
dhutch said:
Interesting thoughts, especially about BBC Micros in industrial. Which if there is a machine shop on the floor below is effectively what we have here.
These days, it's probably got a switch mode power supply which gives a little isolation from mains spikes, and a little more protection on the interfaces?
That said, we were pretty good at blowing things up back then, 'no pacemakers beyond this point' and all that.
BBC micros (well almost all of them) had switch mode PSU's, even the Apple ][ did.

Stuff like PET's and N*'s didn't

ruggedscotty

Original Poster:

5,606 posts

208 months

Saturday 25th March 2023
quotequote all
Gary C said:
OutInTheShed said:
dhutch said:
Interesting thoughts, especially about BBC Micros in industrial. Which if there is a machine shop on the floor below is effectively what we have here.
These days, it's probably got a switch mode power supply which gives a little isolation from mains spikes, and a little more protection on the interfaces?
That said, we were pretty good at blowing things up back then, 'no pacemakers beyond this point' and all that.
BBC micros (well almost all of them) had switch mode PSU's, even the Apple ][ did.

Stuff like PET's and N*'s didn't
Had a couple of switchmodes big boys for computers, unpacked checked books and went for coffee and to pull out the dummy loads....

got back apprentice had wired them up and then plugged them in, no load..... had to send them back. apprentice had never seen a power supply go bang before, early type smpsu and could not be powerd up with no load...

Gary C

12,315 posts

178 months

Sunday 26th March 2023
quotequote all
ruggedscotty said:
Had a couple of switchmodes big boys for computers, unpacked checked books and went for coffee and to pull out the dummy loads....

got back apprentice had wired them up and then plugged them in, no load..... had to send them back. apprentice had never seen a power supply go bang before, early type smpsu and could not be powerd up with no load...
Ouch, expensive mistake.

AW10

4,422 posts

248 months

Sunday 26th March 2023
quotequote all
dhutch said:
I'm not a spark, and it might not be what you would do in an ideal situation, but assuming everything down stream is able to be protected by a 20A breaker (ie, the cable to the second socket is a suitable gauge) I believe it is allowed, just like having a radial of ten 13A sockets off a 20A breaker.

Which if two lifts is the new one?
Sorry, missed this reply.

I've checked the details and realised I got my wires crossed slighty (sorry, bad pun). The existing lift is on a dedicated 16A type C RCBO and uses a 16A commando plug/socket connected via a roughly 12m run of 2.5mm twin and earth. The new lift requires a 20A Type C breaker. So right thing is to run that separate circuit using a dedicated 20A Type C RCBO and 32A commando plug/socket.

Lonoxe

174 posts

31 months

Thursday 27th April 2023
quotequote all
I'm preparing my 3 phase connection before UKPN comes along. I've been quoted either a Wylex REC4 isolator or Crabtree Fusestar switch fuse. There's quite a big difference in price. For the expert, is it worth going with the Crabtree Fusestar switch fuse and paying £450 more or is the value not as much? Thanks