I
itsonly3wires
Hello, I've got a question that I thought I throw out to the crowd and see what comes back... I am a little stuck with a recent EICR that followed a change of occupier.
The home is 30 ish years old and has been extended several times. It is a fairly large home with swimming pool, multiple outbuildings and annexes.
The main DB is where I am struggling a little.
The supply is single phase fed from two meters. It enters the DB via 25mm2 tails two from one meter. One from the other meter. At a glance it looks like a 3 phase supply... there is a 125A main switch to the DB and there is a single neutral. It is a three phase DC with colours marking out where you would normally expect to find L1, L2 and L3.
The issue I am having is that the single neutral is carrying the entire current from both supplies and so too is the meter it is connected to. One meter has no neutral connection to the DB.
The meter (I think) is rated to 80 amps... but the full load is passing through it.
The tails (meter to DB) are short so I am less concerned about the neutral being overloaded.
The main switch on the DB is rated 125A so should be fine but I imagine the rating is for a reasonably well balanced 3 load across all 3 phases. It isn't. No current is flowing between phases so everything must be going down neutral.
For clarity the main DB is the only source of distribution to the whole building. There are a further 5 sub DB's fed off this one board. The board is near full to capacity at 0.4 diversity.
So my question is this.... any harm in the neutral from one meter handling this load? What about the main switch? Are there any regs transgressions in this? I've never encountered this particular set-up before.
Here is the full horror:
The home is 30 ish years old and has been extended several times. It is a fairly large home with swimming pool, multiple outbuildings and annexes.
The main DB is where I am struggling a little.
The supply is single phase fed from two meters. It enters the DB via 25mm2 tails two from one meter. One from the other meter. At a glance it looks like a 3 phase supply... there is a 125A main switch to the DB and there is a single neutral. It is a three phase DC with colours marking out where you would normally expect to find L1, L2 and L3.
The issue I am having is that the single neutral is carrying the entire current from both supplies and so too is the meter it is connected to. One meter has no neutral connection to the DB.
The meter (I think) is rated to 80 amps... but the full load is passing through it.
The tails (meter to DB) are short so I am less concerned about the neutral being overloaded.
The main switch on the DB is rated 125A so should be fine but I imagine the rating is for a reasonably well balanced 3 load across all 3 phases. It isn't. No current is flowing between phases so everything must be going down neutral.
For clarity the main DB is the only source of distribution to the whole building. There are a further 5 sub DB's fed off this one board. The board is near full to capacity at 0.4 diversity.
So my question is this.... any harm in the neutral from one meter handling this load? What about the main switch? Are there any regs transgressions in this? I've never encountered this particular set-up before.
Here is the full horror: