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Traineeboy

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Murdoch

Re EV's - the issue is cost, followed by EV charge points (which can be a red herring) as people think they drive further than they actually do. I recall that the average journey in the UK is under 10 miles - so range isn't the issue

 

If Governments around the world were truthful - changing all our minds on petrol isn't going to happen and most modern diesels can be cleaner than a lot of petrol cars.

 

Pardon the pun but to drive down the emissions, they should legislate against gas guzzlers .......... more directly than they are doing now and small isn't always good as a small car with a very powerful engine can burn a lot of fuel.

 

 

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Zeespark

Traineeboy, have a look on Youtube for a chap named SparkyNinja, He has just done a webinar on this exact subject, very well worth a watch, I would keep a notepad and a pen handy for it.

 

AndyGuinness

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UNG
1 hour ago, Murdoch said:

Re EV's - the issue is cost, followed by EV charge points (which can be a red herring) as people think they drive further than they actually do. I recall that the average journey in the UK is under 10 miles - so range isn't the issue

 

If Governments around the world were truthful - changing all our minds on petrol isn't going to happen and most modern diesels can be cleaner than a lot of petrol cars.

 

Pardon the pun but to drive down the emissions, they should legislate against gas guzzlers .......... more directly than they are doing now and small isn't always good as a small car with a very powerful engine can burn a lot of fuel.

 

 

 

While the cost of an EV makes it very much a considered purchase the issue will always be that an EV's range is a bit of an unknown with some having a range of as little 60 - 80 miles in some adverse conditions, while the average journey may be under 10 miles travelling between 5 -6 jobs in a day could be multiple journeys of 5 - 10 miles, add into that the possible need to have a top up charge during that day when a fuel top up isn't a quick splash and dash on the forecourt means more planning is needed

 

It will be difficult for a lot of people to move away from the flexiblity the ICE gives us as the limitations of the EV become even more apparent over it's petrol and diesel equivalents

 

Never quite understand the term "gas guzzlers" while some people don't need a big vehicle there are others who pick a vehicle to meet all their needs throughout the year rather than have a number of vehicles on the drive. The bit I find hard to work out is how they arrive at the vehicle emissions I have a Seat Alhambra it's a big car but it returns 35 - 40 mpg round town on a long run I get up to 60 mpg the road tax is £240 there are plenty of small less fuel efficient vehicles out there that pay a small fraction of what I pay in road tax because they have lower emissions. It really needs some clarity how can a gallon of fuel in one vehicle produce less emissions than a gallon of fuel in another given the same mpg

 

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Evans Electric
6 hours ago, Murdoch said:

Wonder when the grid will start asking installers to consult them for approval and they then they get turned down

I read somewhere about putting a notification in when installing  an EV  charger .    

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Murdoch
3 hours ago, UNG said:

 

Never quite understand the term "gas guzzlers" while some people don't need a big vehicle there are others who pick a vehicle to meet all their needs throughout the year rather than have a number of vehicles on the drive. The bit I find hard to work out is how they arrive at the vehicle emissions I have a Seat Alhambra it's a big car but it returns 35 - 40 mpg round town on a long run I get up to 60 mpg the road tax is £240 there are plenty of small less fuel efficient vehicles out there that pay a small fraction of what I pay in road tax because they have lower emissions. It really needs some clarity how can a gallon of fuel in one vehicle produce less emissions than a gallon of fuel in another given the same mpg

 

 

 

My misses used to have an "ecotech" 1 litre Focus - road tax £20 / year. Economy - about 35 around town, 42 on a motorway if you drove carefully - no where near the claimed figures

 

My 2l T6 - will give around 40 on a motorway and being diesel will pull up any hill far better than the Focus!

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Traineeboy

Still learning during this lockdown. 

 

Just a question in regards to testing if you are on the live set of tests and testing at a garage board. When you measure the ZE and remove the incoming earth from the garage DB (because of parallel paths )I presume you keep the earth connected in the main consumer unit ? As I am only measuring the ZE at the garage unit DB. 

 

I obviously then know with my result I add my my ZE to my R1 + R2 readings to get me ZS reading.

 

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Murdoch
13 minutes ago, Traineeboy said:

Still learning during this lockdown. 

 

Just a question in regards to testing if you are on the live set of tests and testing at a garage board. When you measure the ZE and remove the incoming earth from the garage DB (because of parallel paths )I presume you keep the earth connected in the main consumer unit ? As I am only measuring the ZE at the garage unit DB. 

 

I obviously then know with my result I add my my ZE to my R1 + R2 readings to get me ZS reading.

 


why would you disconnect the incoming earth at the garage dB?

 

 Surely that would mean there is no earth and remember your tests of the new sub main give you zdb at the garage cu

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Traineeboy

Ok just to confirm. 
 

if I was measuring Ze at the main CU I would remove the main incoming earth due to parallel paths but at the garage CU as it’s not a Ze I would be measuring ,it would be Zdb I wouldn’t remove any earths ? I just thought that if I left the earth in the garage unit it would then pick up parallel paths from the main CU via the gas and water bonding ? 

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Murdoch
52 minutes ago, Traineeboy said:

Ok just to confirm. 
 

if I was measuring Ze at the main CU I would remove the main incoming earth due to parallel paths but at the garage CU as it’s not a Ze I would be measuring ,it would be Zdb I wouldn’t remove any earths ? I just thought that if I left the earth in the garage unit it would then pick up parallel paths from the main CU via the gas and water bonding ? 

 

Put it this way, would you disconnect the main earth if you were testing a new immersion circuit - answer no. 

 

Would you disconnect the main earth to test any final circuit / submain?

 

I'm assuming the garage isn't TT BTW

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Traineeboy

Right got ya. I assume if the garage CU was connected via Henley blocks (spilt tails) then it would be a Ze at the garage board. 
 

 

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Murdoch
59 minutes ago, Traineeboy said:

Right got ya. I assume if the garage CU was connected via Henley blocks (spilt tails) then it would be a Ze at the garage board. 
 

 


 

what is the earthing arrangement at the out building?

 

 

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Traineeboy

It will use earth from the CPC on the SWA which is connected to the a main CU which is earthed via a TN-S system. 
 

but was asking if the garage unit was connected via Henley spilt tails ( main earthing system TN-S) then the measurement at garage unit would be Ze not Zdb . Is that right ? 

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Andy™
8 hours ago, Traineeboy said:

It will use earth from the CPC on the SWA which is connected to the a main CU which is earthed via a TN-S system. 
 

but was asking if the garage unit was connected via Henley spilt tails ( main earthing system TN-S) then the measurement at garage unit would be Ze not Zdb . Is that right ? 

 

Ze is external to the installation. so if your installation starts at the henley blocks then since the shed DB is at the end of your cable then youll be measuring Zs of the submain, which would also be Zdb, not Ze

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Evans Electric
On 23/04/2020 at 17:32, Murdoch said:

Measuring in feet suggests a very mature trainee.

Not even I measure in feet  Murdo .  

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Traineeboy
On 20/05/2020 at 19:12, Andy™ said:

 

Ze is external to the installation. so if your installation starts at the henley blocks then since the shed DB is at the end of your cable then youll be measuring Zs of the submain, which would also be Zdb, not Ze


ok thanks . So if I was calculating Zs of say a lighting circuit off the Garage DB. I would measure the Ze at a Henley block/isolation switch. The R1 and R2 of the lighting circuit. 
 

would it be Zs = Ze ( R1 + R2) Ze measured at Henley block or Isolation 

 

or would it be Zs = Zdb ( R1 + R2) Zdb measured at the garage CU main switch. 

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Murdoch
10 hours ago, Traineeboy said:


ok thanks . So if I was calculating Zs of say a lighting circuit off the Garage DB. I would measure the Ze at a Henley block/isolation switch. The R1 and R2 of the lighting circuit. 
 

would it be Zs = Ze ( R1 + R2) Ze measured at Henley block or Isolation 

 

or would it be Zs = Zdb ( R1 + R2) Zdb measured at the garage CU main switch. 

 

or:

 

Ze + (R1 + R2 for the submain) + (R1 + R2 for the circuit in question)

 

If that makes sense

 

Watch your volt drop too - especially on long submains 

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Traineeboy

thanks to all who take the time to reply. Another thing I just want to clarify. 
 

If say you have 15 led downlights on one circuit and they are equivalent to 50w a light. So 750W divide by 230 = 3.2 A 

 

But the 6A circuit breaker keeps tripping am I right in thinking as long as there isn’t a fault then it’s due to inrush current. This can then be rectified by fitting a type C MCB rather than a type B ? 

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Phoenix

The 50w is irrevelant, thats the manufacturer saying "This light is as bright as a 50W tungston halogen", do your calaculation using the actual wattage of the fitting, though I'd still use the 1.8 fiddle factor, even though that might be a bit different for LED, its a good starting point. And us going to a breaker with a higher instantous tripping threadhold is one answer, subject to Zs constraints and also thermal withstand of the CPC (unlikely to be an issue here, but its one that I bring up when someone wants to fit a D type to a lighting cirucit in a commercial premises wiried in T/E). Other ways are don't have all the inrush at the same time; switch the lights in smaller banks, then you will have separate peaks of inrush rather than one big one.

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Murdoch
2 hours ago, Traineeboy said:

thanks to all who take the time to reply. Another thing I just want to clarify. 
 

If say you have 15 led downlights on one circuit and they are equivalent to 50w a light. So 750W divide by 230 = 3.2 A 

 

But the 6A circuit breaker keeps tripping am I right in thinking as long as there isn’t a fault then it’s due to inrush current. This can then be rectified by fitting a type C MCB rather than a type B ? 

 

As long as the 15 LED's are on 1 switch in rush is unlikely to be an issue

 

Changing to a typc c will have consequences on your calculations for Zs - so tread with care

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Traineeboy

Thanks . 
 

so it’s better they are on 1 switch than multiple switches ?  
 

If I ever did need to switch to a type C then I guess it’s just knowing the different Maximum permitted Zs of a type c MCB to a type B found is BS7671. 
 

on that subject am I right in thinking that on-site guide is 0.8 of the readings in BS7671. So does that mean that if a reading is 0.9 of the reading in BS7671 it’s a fail or needs to be investigated ? 

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Murdoch
12 minutes ago, Traineeboy said:

Thanks . 
 

so it’s better they are on 1 switch than multiple switches ?  
 

If I ever did need to switch to a type C then I guess it’s just knowing the different Maximum permitted Zs of a type c MCB to a type B found is BS7671. 
 

on that subject am I right in thinking that on-site guide is 0.8 of the readings in BS7671. So does that mean that if a reading is 0.9 of the reading in BS7671 it’s a fail or needs to be investigated ? 


my post has a typo

 

 never put that many led lights on the same switch

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Traineeboy

I assumed so but was just checking 

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binky
17 hours ago, Traineeboy said:

Thanks . 
 

so it’s better they are on 1 switch than multiple switches ?  
 

 

 15 downlights - sounds like a large area y0u are illuminating? I would be inclined to group sets of downlights to give different lighting effects,  eg in a kitchen, I would separate an island unit / under cupboard lighting / and general area lighting so the customer can have soft lighting / full on bright lighting depending on what they are doing.

 

As for in-rush currents, these are in the order of micro-seconds and should not be picked up be a breaker type B or not. in my opinion, tripping MCB is more to do with the quality of downlighter used.

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Murdoch
4 hours ago, binky said:

 

As for in-rush currents, these are in the order of micro-seconds and should not be picked up be a breaker type B or not. in my opinion, tripping MCB is more to do with the quality of downlighter used.


 

some manufacturers do have recommendations for the maximum per circuit

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binky
3 hours ago, Murdoch said:


 

some manufacturers do have recommendations for the maximum per circuit

not noticed that, but I still recon quality of components is main issue.

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