Isolators

**Sparks** · 16-Oct-12, 07:46 AM

Originally Posted by RegElec

Thanks for the comments.
This is a job that I am currently working on. The 3 phase cable will be run from a DB for the complete area where lights will be (large factory installation). The cable will run into 4 way CCG boxes and out the other side to the next CCG box and so on. Out of each remaining two ports on the CCG box will be single phase cabling running to 220V lights. The load will be balanced across the phases. The cable according to the regs must be supplied from a multipole CB. That part is fine. Then we run into the regs as above which to me means that I must install a D/P isolator at each 'T' of the CCG box so that each phase including neutral can be isolated allowing the other two phases to continue to work. This cannot be done at the point of supply (DB) because I will have to isolate the neutral in the cable so all lights will go off anyway.

In this case I would run a multi core cable down and mount an isolator where it can be accessed. Either at each area or below the first split, one for each phase, if it would not disrupt the work if a whole phase is dead.

**houtkop** · 16-Oct-12, 09:43 PM

Dankie manne hier leer ekke sommer baie. Dis baie lekker om sulke gesprekke te kan volg. Ek hoop julle verstaan afrikaans lol

**RegElec** · 17-Oct-12, 06:27 AM

Thanks Sparks. The problem with that is that there is only one neutral in the cable which has to be isolated so therefore all phases would have to be isolated as well which is in contradiction to the regs as far as ""... in order that maintenance work can be carried out without switching off all the lights"

The only option that I can see is to place a D/P isolator at each branch to a fitting which in this case is not going to happen as there are +- 450 fittings.

I will be phoning the ECA today to see what their interpretation is and will report back with the answer.

**Sparks** · 17-Oct-12, 07:56 AM

Originally Posted by houtkop

Dankie manne hier leer ekke sommer baie. Dis baie lekker om sulke gesprekke te kan volg. Ek hoop julle verstaan afrikaans lol

Baie welkom hier tussen ons. Alhoewel jy welkom is om nog te leer, sien ons ook uit na jou bydrae. Skop gerus jou skoene uit en maak jou tuis. Voel ook vry om enige vrae in Afrikaans te stel. Terminologie kan soms verwarrend wees as dit nie in jou eie taal is nie.

Loer ook gerus by die ander disipline se blaaie in, daar is ook baie interesanthede.

**Leecatt** · 17-Oct-12, 07:56 AM

Originally Posted by RegElec

Thanks Sparks. The problem with that is that there is only one neutral in the cable which has to be isolated so therefore all phases would have to be isolated as well which is in contradiction to the regs as far as ""... in order that maintenance work can be carried out without switching off all the lights"

The only option that I can see is to place a D/P isolator at each branch to a fitting which in this case is not going to happen as there are +- 450 fittings.

I will be phoning the ECA today to see what their interpretation is and will report back with the answer.

Since you are doing the initial installation can you not divide the lights up into section such as individual rooms, or the building floor into west, east, north etc and then have one isolator installed for each section in one lockable DB situated centrally.

**Martinco** · 17-Oct-12, 09:11 AM

Is jy die Houtkop wat ek ook ken ?

**RegElec** · 18-Oct-12, 06:35 AM

I contacted the ECA yesterday and spoke to them regarding my installation and that regulation. Their comment was that the regulation commonly applies to a row of lights where the neutrals are looped in and out of fittings. The purpose of the regulation is to prevent a fitting being removed thereby causing a danger with a broken neutral.

I questioned them regarding my application and they are happy that the three phase circuit is supplied through a T/P C/B without any further need of isolators. Personally I dont see how that is correct according to the wording of the regulation but if they are happy then I will continue as the project was originally planned with just a T/P C/B with warning labels in the junction boxes stating three phase supply.

**Sparks** · 20-Oct-12, 06:45 PM

Just more confirmation that ECA have their own ideas about the regs. It clearly states all the phases including the neutral. Being as you say a factory installation I suggest you bring your 3ph cable down to an accessible level and put a lightswitch panel, with DP switches, there for easy access to do maintenance.