I have removed my previous post, due to me being a noob and not counting the pins according to the datasheet.
I have in the meantime managed to get the LCD working.
I have read this post: Serial LCD I2C Module–PCF8574 | alselectro
The post explains in detail what each pin does and where it's connected to etc.
I used my multimeter in continuity mode to trace the pins from the chip to where they are connected to the LCD, as per bperrybap.
I have found one exception with using the PCF8574A:
I have to specify the backlight pin.
//LCD
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7); // Set the LCD I2C address
#define BACKLIGHT_PIN 3
void setup()
{
Serial.begin(9600);
emon1.voltage(A0, VOLT_CAL, 1.7);
emon1.current(A1, 6.5);
lcd.begin(16,2);
lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);
lcd.setBacklight(HIGH);
pinMode(8, INPUT_PULLUP);
attachInterrupt(digitalPinToInterrupt(2), IntTrig, CHANGE);
}
I have also noticed that my text on the LCD seemed to be chopped off - it turns out it was a dry joint on the pin to the LCD.
Thanks to all for the advice. SOLVED.