Hot Swapping !!
Welcome to the Blog section of our MG Lites website
In this section, we will provide regular informative articles/discussion points for anyone with an interest in the lighting industry – especially regarding the use LED products.
This month’s subject looks at the controversial practise of hot swapping DC connections on products such as LED panels /downlights- while still running from an AC supply:
What is hot swapping ?
Hot swapping is when a product has its AC or DC connections disrupted [or lamp removed/inserted] during mains operation.
This was a common practice in the days of fluorescent lighting, but is not recommended for a multitude of reasons-primarily, because isolating the AC supply before commencing electrical work is a vital/ compulsory practice - when working in accordance with 17th edition wiring regulations.
In the case of LED products - hot swapping is when an LED drivers DC output is connected or disconnected while the product is still operating from the AC supply.
Why hot swap?
1. Sometimes, if an LED panel goes faulty onsite, the installer may unplug/plug the DC cable to change the panel/downlight for a new working one – but without isolating the main supply first to save time.
2.During installation - Installers may wire the driver to the AC supply first [with the mains still switched on] and then connect the DC output to the products LED array- unaware of the potential damage it can cause in the long term.
3. When replacing products damaged by hot swapping during the first installation – installers may unknowingly go about replacing the faulty LED arrays by hot-swapping, only to find the problem occurs again and again – if the supplier is unaware that hot swapping is the initial cause, the situation can go on indefinitely [with ever rising costs and inconvenience].
Why would this cause a problem ?
1. When connecting /disconnecting DC power to the LED arrays, the LEDs can be damaged by voltage spikes caused by disconnection and air static discharges [as the LED array is disconnected from the drivers protection circuitry – so it can no longer provide air static discharge protection for the LEDs]
2. Some drivers will output the maximum output voltage when not connected to a load – when the array is connected a brief overvoltage/overcurrent spike can occur which can damage the LEDs in the array [this damage can lead to premature failure of the LED].
3.The drivers and arrays are not designed for this usage- thus, the warranty of the product is invalidated.
It is understandable, that electrical engineers, who are more used to working with older fluorescent technologies do not know how LEDs can be electrically damaged by hot swapping [as this is a new technology and electricians are not expected to know everything about the luminaires electronic design aspects]. Manufacturers assume, the product will not be hot swapped -as hot swapping goes against 17th edition wiring regulations- so in the market, very little is done educate the installer/electrician, as they are expected to already to use the practise of isolating the mains, as part of their workplace safety code and compliance to wiring regulations.
Are there any circumstances where hot swapping is acceptable?
No- as it goes against wiring regulation practises/can void product warranty and can electrically damage the LED components –leading to product failure.
To hot swap is to interfere with the products intended electronic design – unless the product clearly states it has such a capability [such drivers/arrays may cost more], we advise that all LED products of all makes/models should be regarded as not hot swappable [ this simple advise can save site users /installers and lighting companies a great deal of inconvenience and time].
While hot swapping initially appears to save time - in the long term it has the opposite affect, our advice to installers is to take the extra time to isolate the mains during work- so the work only has to be done once.
While all MG Lites LED drivers are SELV type with protection against short and open circuit operation /thermal overload –the LED arrays [ such as panels /downlight modules ] rely on the drivers internal protection circuity to maintain reliability –on the assumption that the product will be installed correctly without hot swapping.
We sincerely hope you found this blog informative and useful.