{"id":64,"date":"2025-12-11T11:27:41","date_gmt":"2025-12-11T11:27:41","guid":{"rendered":"https:\/\/blog.lyco.co.uk\/blog\/?p=64"},"modified":"2026-03-06T13:11:47","modified_gmt":"2026-03-06T13:11:47","slug":"power-factor-avoiding-the-surcharge","status":"publish","type":"post","link":"https:\/\/blog.lyco.co.uk\/blog\/power-factor-avoiding-the-surcharge\/","title":{"rendered":"Power Factor: Avoiding the surcharge"},"content":{"rendered":"\n
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Posted on 3 June 2014<\/p>\n\n\n\n

Author: Andrew Evangelidis<\/p>\n\n\n\n

Last updated on 30 March 2022<\/p>\n<\/div>\n\n\n\n

Power factor is a lesser known specification in the world of lighting. It measures how efficiently power is used in an AC circuit, and is a closely scrutinised area of LED and fluorescent lighting. Despite being vastly more energy efficient than filament lighting, these newer technologies have a naturally low power factor. This may seem trivial when compared to their substantial benefits, but has, regardless, been subject to EU regulations in recent years.<\/p>\n\n\n\n

Energy suppliers surcharge commercial customers for use of low power factor equipment. This is openly itemised as either a power factor charge or reactive power charge, and billed in units of kVAr. Large, complex buildings with numerous luminaires will plainly be more affected. Low power factor also reduces the number of fittings installable on a lighting circuit.<\/p>\n\n\n\n

By choosing energy efficient lighting with a high power factor, energy savings are truly maximised, meaning you should not be hit with such a surcharge. To go straight to our high power factor products click here<\/a>. Alterntively, read on to really understand what the power factor is all about\u2026<\/p>\n\n\n\n

The power factor calculation<\/h2>\n\n\n\n

Power factor is calculated by dividing the active power <\/em>used (in watts) by the apparent power <\/em>drawn from the power grid (in volt-amps, or VA). A unitless number between 0.0 and 1.0 is used, with 1.0 representing 100% unity (i.e. 1 volt-amp = 1 watt).<\/p>\n\n\n\n

Circuits containing only heating elements have a 1.0 power factor. This includes the resistive circuit of an incandescent lamp, where current increases and decreases proportionately with voltage (meaning the current and voltage are \u2018in phase\u2019).<\/p>\n\n\n\n

LED and fluorescent circuits have inductive or capacitive elements, and never have a 1.0 power factor. Voltage and current are always out of phase to some degree, with only the in-phase portions producing real work. Power factor correction (PFC) can be installed to bring voltage and current more closely into phase. Any unused power is called reactive power<\/em>.<\/p>\n\n\n\n

Power factor charges<\/h2>\n\n\n\n

Commercial customers are surcharged for reactive power in units of kVAr. Suppliers apply a power factor threshold of between 0.85 and 0.95, above which there is no charge. Domestic users are never billed for reactive power.<\/p>\n\n\n\n

Examples:<\/p>\n\n\n\n