Just wondering how to connect each end of the same cable together without twisting them together and wrapping insulation tape round which is messy. The cable is a three core and earth. Could I use a junction box to connect them back together. I've looked online but can't find diagrams for this specific cable and all cores need to be connected because its running to a fire alarm. A junction box would be great if I can use one in this situation so I can add a spur later on.
It does depend what cable and where it is. Ali-tube cable is designed to be fire resistance not as good as mineral insulated but considered good enough for most fire alarms.
It may be required to join inside a conduit box to afford the same fire resistance as the cable. No cable is fire proof it's down to how long it will survive in a fire. In the main the bulk of a metal box will take some heating up which means it will outlast the cable.
In some cases the cable is only thermal plastic and the idea is failure of the cable will make the fire alarm sound.
What is needed is a risk assessment and one has to envisage the likely scenario in the case of a fire. Clearly in a high rise block of flats this is very different to a bungalow and there is no one size fits all.
In some cases a simple maintenance free junction box is all that is required.
Google "maintenance free junction box" and see if they seem to fit the bill.
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