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Would you not be better having the neutral link on the incoming side of the isolator? As it is now, you could have double the cutout rating current flowing on one pole of your isolator.
An odd supply...
- Thread starter Lectrician
- Start date
There is a link top and bottom. The top one can't be seen. As this is split phase, the phases are 180deg apart, meaning one phase is pushing as the other is pulling. This means the neutral will only ever carry the current of the highest phase, not the total of the phases.
There is no neutral marking on the four pole isolators. There is on the 3 pole fixed neutral (obviously).
I did want to use an excel switch, but there where issues with the wholesaler twice. For some reason they kept sending me 100amp switch-FUSES. I didn't want them fused.
CU's are at the height requested. They are on the only free wall available, and are better at the height they are due to the door TBH.
As for metering, it is done exactly as three phase, except there is a phase missing.
As I say, I am not particularly happy with this main isolator, but am happy enough to go with it.
H
holmslaw
..
This is what one may also look like:
View media item 20581
There are two, single phase meters connected to this 5-core cable.
The blue core is taped back onto the sheath.
Thats with the lower cover removed by the looks of it - you can see the colour difference on the wooden back board.
If the lower cover was not used, that is as rough as houses!
You could have two meters, but these days they just use a standard polyphase meter.
If the lower cover was not used, that is as rough as houses!
You could have two meters, but these days they just use a standard polyphase meter.
Thankfully this one should be gone soon, but I wouldn't know for sure if it had a cover originally.
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No, the MEM Glasgow were rated to 1000V and installed with a bottle of scotch next to them.
On a serious note, I like the way it's been wired. Like a meter, the lines on the outside and the neutrals in the middle.
P
Paul_C
Seems curious for a 4-pole isolator which by its 415V rating is clearly intended for use with a regular 240/415V wye system.
P
Paul_C
Just for interest.....
I may try to take some pics with my actual camera at some point to replace these shots.
Pole mounted TX - two HV overhead phases. (11kv).
Closer view of terminations - notice two fuses for each of the split phases.
Closer view of terminations. I have labelled so you can see, as pics not too clear. Should take my camera really. Notice the cable used is a split concentric three phase type (it will likely be waveform, but cannot tell obviously). The grey is unused and just clipped to the pole. The end is not terminated.
Service head. Standard TPN service head used.
Service head with the cover off. Here is the issue. The supply should be TN-S. It was requested and designed as TN-S, but the DNO chappy who fitted the service head has fitted one with combined N/E. After discussions with the DNO designer, he has decided to use the unused grey as a neutral, using a solid link in place of a fuse in the service head. (withdrawable). The blue/bare concentrics can then be used soley as the earth.
No metering installed yet, but it will be just a standard polyphase meter that will be installed.
I may try to take some pics with my actual camera at some point to replace these shots.
Pole mounted TX - two HV overhead phases. (11kv).
Closer view of terminations - notice two fuses for each of the split phases.
Closer view of terminations. I have labelled so you can see, as pics not too clear. Should take my camera really. Notice the cable used is a split concentric three phase type (it will likely be waveform, but cannot tell obviously). The grey is unused and just clipped to the pole. The end is not terminated.
Service head. Standard TPN service head used.
Service head with the cover off. Here is the issue. The supply should be TN-S. It was requested and designed as TN-S, but the DNO chappy who fitted the service head has fitted one with combined N/E. After discussions with the DNO designer, he has decided to use the unused grey as a neutral, using a solid link in place of a fuse in the service head. (withdrawable). The blue/bare concentrics can then be used soley as the earth.
No metering installed yet, but it will be just a standard polyphase meter that will be installed.
P
Paul_C
There are quite a few 1-ph 3-w 240/480V distribution systems in use around my area of rural Norfolk. I dug out these photos from a few years ago - Not the greatest quality as I think they were taken with a little pocket camera, but you can clearly see the 3-wire arrangement and two fuses on the pole:
And here's another one a few miles away from the first - A PME connection is clearly visible on the neutral in the third picture:
And here's another one a few miles away from the first - A PME connection is clearly visible on the neutral in the third picture:
P
Paul_C
Different voltage ratings on different Exel units then.
Fancy a game of semantics while we prove who is right? 
P
Paul_C
How about we settle on them just being suitable for 480V? 
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