Red diesel again

[john87]

2 hours ago, topchippyles said:

63A MCB on my board 

Ok. there is a LOT more to it than that..

 

You see, you select the OCPD [overcurrent protection device [usually a circuit breaker] to suit the load. This is first step..

So, if you had a 60A load, you would select a 63A MCB

 

Then you need to know what type.. They come with different "characteristics" you see, [their characteristic curve]

 

These are "B" "C" and "D"

 

Basically, this is how sensitive they are. If you tried to use a "B" curve with an inductive load like a transformer or motor it would almost certainly trip on startup, so you MIGHT be able to fit a "D" curve [which would be ok]

 

Trouble is, you can only do this if the circuit "Zs" that is the "EFLI" [earth fault loop impedance] is low enough..

 

If it is not, in the event of a fault you will not meet the required "disconnection times" and so, not only would your circuit not comply with the wiring regs, but in the event of a fault, the wiring would be damaged by heat BEFORE the breaker operated [if it operated at all] AND, even worse, if the fault resulted in you receiving a shock, since the required disconnection times would not be met, the power might not be shut off at all, and you would be dead..

 

I have personally seen an air compressor [on a farm] where despite me telling the farmer that the circuit impedance was too high, i got ignored, and as a result, one day the motor failed to start and literally melted into a large lump of molten aluminium, without tripping the breaker at all..

 

john..

[dumper]

17 minutes ago, john87 said:

It does not work like that..

 

The DNO will ask you LOADS of questions along the lines of;

 

What are you connecting up?? For EACH load they will want to know load in KVA [NOT kw] how long will each load be running a day, between what hours, what type of starter DOL or star/delta and how many stops and starts an hour.

 

They will also want to know in particular about any single phase motors bigger than half horse power and any welders.

 

They will want to know what lighting and what heating too..

 

Once they know all this, they will calculate IF they are prepared to offer you a supply [by no means certain] and what size supply they will give you..

 

It all revolves around what they think they can give you without affecting other consumers as they have a legal responsibility for the quality of power they supply..

 

100A is the usual standard industrial supply size, it is an awful lot of power as it is 100A PER PHASE so the total power would be 400V x 1.732 [it is the square root of three, don't ask!!] x 100 = 69.3 KVA

 

john..

Due to mistakes made by ukpn and that the linesmen owe me a big favour they are giving me three phase power connection, do I ask for 100 amps per phase I would like to power a welder and a lathe plus a car charger my biggest problem at the moment is getting a meter

[scbk]

This turned from an interesting thread on diesel to a confusing thread on electricity 

 

 

I wonder where the red diesel price will be in a months time, will things settle down after the April 1st changes

[dumper]

Oops sorry for the derail 

[openspaceman]

3 hours ago, dumper said:

Why no smart meter?

When they fitted mine they replaced the 100A one with a 60A

 

I'd better correct that, the fitter said it was 60A but I just went out and looked at the meter and it's rated at 100A

Edited March 26, 2022 by openspaceman
correction

[john87]

19 minutes ago, dumper said:

Due to mistakes made by ukpn and that the linesmen owe me a big favour they are giving me three phase power connection, do I ask for 100 amps per phase I would like to power a welder and a lathe plus a car charger my biggest problem at the moment is getting a meter

What size welder what size lathe?? send me photos of nameplates on machines

 

john..

[difflock]

13 hours ago, Squaredy said:

Good question!  I have split phase supply, which is actually further divided into three phases (but not true three phase) so there is plenty of power to run the thirty hp inverter.  Inverter needs two 60 amp feeds, I have three 80 amp feeds.

When we signed for our new single ph supply back in 1995, it was stated in black and white that NIE would only stand over the 230V at a heady 8kW loading.

We were and are on a dead end spur from the village that was provided to supply 1 dwelling only, then others were subsequently added.

 Anyway I queried this since our Belling cooker could have drawn 13kW, plus lights, plus 2kW electric kettle  a 3kW immersion heater plus 8kW electric shower.

it did not add up.

I did note when I filled in the paperwork for the 3Ph application, that they now quote 18kW instead of 8.

But still  .  .  .

I will wait until I get the kit next Wed, and check out the motor sizes, to see what I need.

It must be said  would prob prefer the simplicity of an inverter.

 

[difflock]

So what would it take to start and run a 30HP DOL motor, then add another 10HP DOL motor?

[Squaredy]

13 minutes ago, difflock said:

So what would it take to start and run a 30HP DOL motor, then add another 10HP DOL motor?

I am no expert but a 30hp DOL motor will have a massive load on startup.  Electric motors can have a huge startup demand - easily six times running load maybe ten times.  You really want a soft start of some sort for that size motor!  Resistive loads on the other hand (heaters etc) do not have a high startup load.

 

Ongoing load from a motor once up to speed can be very low on the other hand.  I used to run a kiln that had two 3kw fans running 24/7.  I calculated this would cost around £600 per month to run (simple maths: 6kw per hour X 24 hours and 30 days per month = 4320 units per month) but in fact bills barely noticeably more than normal.

[john87]

1 hour ago, difflock said:

So what would it take to start and run a 30HP DOL motor, then add another 10HP DOL motor?

Obviously it is possible wire things any way you like, but no way would anyone but a looney try to wire a 30 hp motor to start direct on line... You would not be able to buy a DOL starter that big anyway..

 

john..