Dedicated radial on 3 phase supply

Would anyone here be able to help out with a line diagram of what a dedicated radial might look like, taken from a 3 phase + neutral supply?

There is a 3 phase breaker between the meter and single phase breaker panel which belongs to the supply company, so I’m pretty sure it won’t be legal to connect upstream of the breaker i.e. just after the meter, or to the breaker itself for that matter.

It would be great to have a diagram to use as a basis of discussion with the sparky, if anyone could help out…?

From your description you have only single phase to your property if you only have one single phase breaker?
Your sparky should be able to confirm this.
If you have three phase supply, again your sparky should be able to balance the load normally. He then can use whichever phase is supplying your hifi to run a dedicated circuit from that phase.

(All properties are 3 phase, its just split before it enters your property. ie, one street may be on phase 1, the next street on phase 2, the next on phase 3, etc.)

It’s likely the supply into your house is a single phase and neutral. Even if you do have a 3 phase supply into your property, each consumer unit/ fuse board will only be single phase and neutral.

Sorry, I described the set up badly.

The supply into to the house is 3 phase & neutral. It comes from the meter to a 3 phase circuit breaker, inside the garage but still owned by the supply company. From there the phases are distributed in the main circuit breaker panel via mccb and 2 pole mcb’s for single phase distribution throughout the house. It also goes to a 3 phase panel which feeds the hydraulic motor for a lift.

Im trying to communicate with the sparky from a distance (I’m away from home) so that it can be incorporated with other work on the house, scheduled for completion before I return. It would greatly ease the communication if I could share a drawing with him but I haven’t managed to find one online and I’m not sure enough myself to sketch it out.

I will ask that the distribution is rebalanced and that the sockets in the listening area are put on the “quietest” phase. I guess that means one without the fridge but with LEDs all over the place I’m not sure what’s worse. Obviously the dedicated radial will have to come off that phase.

I will also ask if a dedicated earth can be safely/legally installed rather than connecting to the neutral. I don’t see an earth as such, just the neutral but the sparky will have to advise on that.

At the end of the day, it might not be possible if there’s not enough room in the existing conduit so the best I could do is connect to a quiet phase. I do want to try though and want to be as clear as possible with the sparky- we are not communicating in my native language and there are limits to my technical vocabulary. A picture paints a thousand words s they say…

Just a note of caution here. Different countries have different code requirements so ultimately, unless a member here is fully knowledgeable of the current electrical code for the country or even area of a country where you live, then approach any electrical advice given here with great caution. Better to ask a fully qualified and accredited electrician local to where you live.

Caution noted Richard and the work will be undertaken by a fully accredited electrician, to code.

Unfortunately, finding an electrician with experience in installing a dedicated radial has so far been unfruitful so I was simply hoping for some assistance with considerations and a starting point for discussion with the sparky.

Is this a UK based install or some other country?

No, I am outside of UK - Andorra.

As Richard suggest, local codes will apply. I doubt that the neutral is an earth in the way you describe. There will be a separate earth somewhere even if it is a bonded earth to ground direct from your property. If the leccie agrees that a new earth can be connected he will know where to place and connect it. I don’t see any reason why that can’t be included. As you say the physical space and positioning of any required conduit to local code may be a limiting factor.
The supply of a dedicated spur from as close as to where the electricity enters your house is not an electrical difficulty if you and the leccie can find a route to where you want it.

1 Like

Since notes of caution seem to be in order… you are probably required to use the same phase that supplies any other sockets in the room. You really don’t want 415V between adjacent sockets.

1 Like

Thanks Andy. I am aware if that, it’s what I meant earlier when referring to the radial coming off the same phase as the sockets in the room.

Cool. I’d missed that…

1 Like

Not what would be good for your hifi gear.

This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.