3 phase loading question

[Steve2381]

Hello all
I am working for a company and we are installing supplies to some industrial 3 phase heaters in a factory in Devon.
I am questioning the maths used by my boss to arrive at the SWA size to supply these heaters.

Seeing as I am not a wiz with 3 phase stuff (only just started working for this firm), can someone give me some pointers on calculating the load?
I know the basics, but would like to make sure I am right before rocking the boat!

We are supplying 4x 15000kw heaters - 3 phase.
What load is that going to be per phase, per heater? He has basically divided the 15000kw into 3 - therefore 5kw per phase, then divided it by 230v.
Arriving at 21.7A per phase.

That means with 4x 3 phase heaters on the distribution board, we are looking at around 88A per phase load.
That's a huge 348A load.

He has 'guessed' at a 35mm 4 core SWA for the 50M run. Not convinced any calcs have gone into that decision.

Thanks!

 

[Guest55]

he sounds a total liability lol.
start looking for a new job before he drags you down.
;-)

 

[micknew]

Your a right pair then.

 

[Tiny Spark]

Think ide be looking for another company in that case!

 

[Steve2381]

Yep... already looking around!

 

[Megavolt]

How is he still in business did he pay to but any of it right ?

 

[GLENNSPARK]

Cock ups... wow, where to begin....

Installing a single phase board in a factory where most of the machines were 3 phase.
Running a huge bundle of cat5e cables in the same trunking as the supplies to the office ring circuits (for about 25M)
Installing a 3 phase SWA and isolator in a garage, and telling the customer to order a 3 phase oven... then I turn up to connect the oven and its only single phase at the incoming.
Frying the entire AV system in a house by fiddling around with things he doesn't understand behind a AV distribution system... and accidentally switching the voltage to 110v (how the hell he did that I don't know).

... just a few things make me worry

....

 

[Darkwood]

If your been payed your wage then ok as non of this is on your shoulders but as others have said look for another job... you seem the brightest in the whole company yet your only have a few yrs experience which worries me to the competence of your work colleagues.

 

[Steve2381]

I am putting way more hours than I am paid to sort out all sorts of messes they leave.
I just can't do work to their shoddy quality.
No - its not really my problem, its theirs.... but if I am installing it... I want it right.
I have NO IDEA how they ever pass their Niceic inspections.
Only been with them for 4 months... and not many more hopefully

 

[GLENNSPARK]

I am putting way more hours than I am paid to sort out all sorts of messes they leave.
I just can't do work to their shoddy quality.
No - its not really my problem, its theirs.... but if I am installing it... I want it right.
I have NO IDEA how they ever pass their Niceic inspections.
Only been with them for 4 months... and not many more hopefully

listen...
i used to work for this fella and he was one of the biggest emptyheads goin...

no i mean it...this guy thought RCDs detected overcurrent
total spacker...the things he did & came out with...i used to despair of it..i really did...

 

[Des 56]

I am putting way more hours than I am paid to sort out all sorts of messes they leave.
I just can't do work to their shoddy quality.
No - its not really my problem, its theirs.... but if I am installing it... I want it right.
I have NO IDEA how they ever pass their Niceic inspections.
Only been with them for 4 months... and not many more hopefully

These are one of things that you will eventually learn grasshopper
Its the individual that matters,its not the parasite that preys on him

 

[Knobhead]

Tony , what a top site . That one has gone straight on my favorites bar ! unk:

At least one person appreciated it. That’s OK by me.

In the future that needle is going to swing further to the left. It may go below legal limits but it will never get to “total shutdown”.

Selective load shedding is in place and has been for several years. A plant I worked on could at a signal from UKPN shed 16MW of load within 20 minutes. More with advance notice.

 

[GMES]

If it's 15,000KW let me know when you switch it on.

I'll watch it on this Dynamic Demand

Cool site tony will take a proper look later

 

[Knobhead]

I think our OP switch the heaters on this morning at 07:30 never seen Dynamic Demand so low before. 49.85 Hz.

As an idea, when you’re late for work “the alarm clock was late going off”, blame it on the grid frequency slowing down!
Somehow I don’t think it will wash as an excuse.

 

[GLENNSPARK]

tony introduced me to this dynamic loading website a few weeks back when him and I were on the phone...
so it was a good little experiment when phil davies came round last weekend for me to get my power quality analyzer out stick it on frequency and check it up against the website...
on the nail...

 

[Silly Sausage]

It does say you can measure the frequency from any socket in the country.
Has anyone seen this site...well here you go

U.K. National Grid status