The issue I have is with an electronic (SCR) soft-start 240v switch rated at 6kw running 5kw IR heating lamps (restive load). With the soft-starter in circuit, activation starts the IR heater tubes ok and they run for 20 mins, but on associated circuits connected to the consumer unit other lamps dim and a sound system goes off momentarily which is a real issue if I have a live music performance running. With the soft-starter removed and the lamps activated from a normal switch there are no adverse effects on other installations , no lamp flicker. and no sound system dropouts.
I have not come across a problem like this before. I am wondering if there could be a phase related issue but this does not answer why the sound system is affected.
Any comments would be appreciated.