3 sp circuits off a tp isolator

[Outspoken]

Lol, .....This sounds as though you are rewriting 559.6.2.3 and you claim to have NICIEC, NAPIT, ELECSA with even the IET agreeing with you?

Maybe the IET made a mistake?.......Lol.

I have re-written nothing and it was after reading that I decided to contact the relevant organisations to get clarity. I'll admit that each one interpreted the "common neutral" in a slightly different way, and I would question if the NAPIT chap I spoke to understood the difference between common neutral and borrowed neutral, however I believe he actually meant the same thing as the others but was poor at explaining that.

I believe, based on the conversation had with the IET that the regulation is meant to be interpreted as each line of lights from a phase would have it's own neutral, but as these would be contactor controlled the neutrals would return to the output side of the contactor, thus making them common, but not borrowed between the phases as would be the case if looped across the phases. The contactor in turn would be protected on the load side by a TP+N MCB and a single phase supply (Taken from one phase) for the coil.

Now that is no different to what I believe the majority of us have done over the years and is in perfect agreement with 559.6.2.3 and I believe (please correct if wrong Mr Skelton) that this is what D.Skelton actually meant in his posts too

Now if you want to interpret the regulation to mean you can use a common neutral and a TP+N on three lighting circuits across phases with the neutral looped and no contactor then good luck to you, but I do believe you would be interpreting it incorrectly and may be criticised during an inspection for this.

 

[D Skelton]

please correct if wrong Mr Skelton

Almost, but not quite lol. The modular pre wired trunking systems and busbar track lighting that I have installed have a neutral that is common and 'looped' between the phases.

This is not classed as 'borrowed' regardless of what some chumps in some corporate entities say as the lighting circuit, although spread across three phases, is still only ONE circuit. Installed correctly, contactor controlled, equally balanced and protected by a TP OCPD in an installation that is properly maintained there is absolutely no danger in this method of wiring.

Worst case scenario, someone makes a hash of a neutral connection and we end up having to replace all the lamps! Which is far different from when the DNOs get it wrong and peoples microvaves and tellies start exploding lol.

 

[Outspoken]

Almost, but not quite lol. The modular pre wired trunking systems and busbar track lighting that I have installed have a neutral that is common and 'looped' between the phases.

This is not classed as 'borrowed' regardless of what some chumps in some corporate entities say as the lighting circuit, although spread across three phases, is still only ONE circuit. Installed correctly, contactor controlled, equally balanced and protected by a TP OCPD in an installation that is properly maintained there is absolutely no danger in this method of wiring.

Worst case scenario, someone makes a hash of a neutral connection and we end up having to replace all the lamps! Which is far different from when the DNOs get it wrong and peoples microvaves and tellies start exploding lol.

Yep, installed a few systems like this over the years and totally agree, fully safe system that is not a borrowed neutral as everything is "self-contained"

 

[Lou7]

How far apart are these sockets ?

 

[Tidy Max]

Been back to the job to fit an insect-o-cutor so i disconnected the singles from the isolator and pulled in a couple of twins. There was a sp db that had been installed next to the tpdb and it had a couple of spare 20A rcbo's in it. Basically its a refurb of a barn into a restauraunt and the previous sparks have done a pretty nasty job from the looks of things!

 

[Dan]

Just bumping some threads in the Electrical Wiring Theories and Regulations forum category here on our Electricians Forums. If this specific topic isn't current, just ignore it, it'll drop off the list in no time. However, if it's something you'd like to contribute to, feel free to reply and bring it back into current discussion.