# Electrical calculations (1 Viewer)

#### Mike B

Where V = Volts - Voltage
I = Amps - Currant
R = Ohms - Resistance

The illustration shows a simple way to remember the three formulae.

From the middle pyramid, we can deduce that I = V/R (i.e. that current flow increases with

increased voltage but reduces with increased resistance).

Where E = Volts - Voltage
I = Amps - Currant
R = Ohms - Resistance
W = Watts - Wattage

You can calculate the amount of power if you know two of the three electrical values – voltage, current and resistance.

See the formulae in the wheel (E, like V, is used to indicate voltage).

e.g. I = W/E or E/R

#### jdk62

The only formula I can ever remember is:

IVy watts is a powerful girl.....

#### Gellyneck

LIFE MEMBER
SMA is no a bad formula!

#### Peter A Forbes

##### Free Member
I have always used E rather than V for volts, all the formulae I remember and use have that notation.

In most daily usage you only need the basics to work out loadings, and in AC calculations Watts = VA X pf or (Volts X Amps) X power factor.

You shouldn't technically use Watts for AC loads unless their power factor is Unity or 1, ie: purely resistive loads.

Peter

#### scotjimland

LIFE MEMBER
I have always used E rather than V for volts, all the formulae I remember and use have that notation.

In most daily usage you only need the basics to work out loadings, and in AC calculations Watts = VA X pf or (Volts X Amps) X power factor.

#### irnbru

LIFE MEMBER
Looks pretty confusing for me.

#### Minxy

LIFE MEMBER
If you think of it as one of the following you won't go far wrong as a basis to then do other calculations:
• the first two items, amps and volts, appear earlier in the alphabet than watts, so remember to multiply the first two to get the last ...

• another way, always remembering it's a multiplication you're doing ... just scratch your head and think ... 'Watts the answer', ie A x V = W

#### Sandancers

Or the true electricians way, if the fuse blows, put in a bigger fuse.

#### olley

My old maths teacher at college, said don't remember formulas, remember answers, like 100c is 212f, play around with 9/5 or 5/9 +or- 32 till it works out right. 250volts at 4amps is 1000watts.

Ian

#### laurieash

So if I put my 2000w electric fire on for 24 hours at 8.7 pence per kwh
how much would it cost me?

#### scotjimland

LIFE MEMBER
So if I put my 2000w electric fire on for 24 hours at 8.7 pence per kwh
how much would it cost me?

2kw x 24hrs x 8.7p = 417.6p

#### Minxy

LIFE MEMBER
2kw x 24hrs x 8.7p = 417.6p
.... unless it had a thermostat and cut out when it reached temperature ...

#### Wildman

##### Free Member
a better duvet is a lot cheaper

#### Minxy

LIFE MEMBER
a better duvet is a lot cheaper
A hoodie and bedsocks works well as does a nice hot dog on your feet!

#### Wildman

##### Free Member
nah can't stand stale bread and fried onions on my feet

#### Minxy

LIFE MEMBER
A hoodie and bedsocks works well as does a nice hot dog on your feet!
nah can't stand stale bread and fried onions on my feet
Neither can I ... so I have one of these ... although when she lets out one of her farts it smells like hot dogs!

#### Gizmouk

I'll stick with power calc and cable sizing Apps ta

#### laurieash

2kw x 24hrs x 8.7p = 417.6p
So of I reduce to 1000w It would be half of that

#### tonyidle

Neither can I ... so I have one of these ... although when she lets out one of her farts it smells like hot dogs!

View attachment 50071
That's just cheating - she's gorgeous!

#### Jaws

LIFE MEMBER
I have always used ( and taught ) is AVO
Avo is a well known make of meter and is always easy to remember
Same as above really but if you draw it like this:

It makes things real easy to remember
Amps Volts Ohms

Note where the cross is...
So you want to know what the voltage is ? A X O ( amps times ohms )
Want to know what amps are gonna be drawn ? V
/ O ( volts divide by ohms )
Or what he resistance is of a circuit ? V
/ A ( volts divide by amps )

#### Minxy

LIFE MEMBER
That's just cheating - she's gorgeous!
.... and don't she know it ... she's got my hubby wrapped round her little toe!

#### pappajohn

LIFE MEMBER
So if I put my 2000w electric fire on for 24 hours at 8.7 pence per kwh
how much would it cost me?
Where the hell do you get leccy at 8.7p per unit ???????

Ours (Npower) is over 15p

#### laurieash

Where the hell do you get leccy at 8.7p per unit ???????

Ours (Npower) is over 15p
7 lakes country park North Lincs

To join in you must be a member of MotorhomeFun

Join MotorhomeFun

• ### Scotland 2023

• Old Rascal
• Entries: 11
Latest entry: North Berwick,
• ### Awaycation Autumn 2023!

• InvictaMoto
• Entries: 4
Latest entry: Molly back...,
• ### The voie verte disused railway map

• suavecarve
• Entries: 16
Latest entry: canal du midi,