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Strange switch-fuse (UK) #111853 03/06/07 09:40 AM
Joined: Aug 2001
Posts: 7,520
pauluk Offline OP
Just count up the violations here. That's if you can figure out what's going on!

[Linked Image]

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Re: Strange switch-fuse (UK) #111854 03/06/07 11:05 AM
Joined: Dec 2001
Posts: 2,492
Texas_Ranger Offline
Oh my goodness!
Red wires mixed up with what looks a lot like yellow/green at the neutral terminal? Black and yellow/green wires going to fuses?
At least one black wire sneaking down to the line side... not to mention a red wire going to the box earth clamp on the right hand side...
Am I correct assuming there is a red wire going to the bottom of the left hand fuse? Would match the yellow and blue wires to the other two.

Re: Strange switch-fuse (UK) #111855 03/06/07 11:07 AM
Joined: Oct 2006
Posts: 745
EV607797 Offline
I don't know much about UK wiring practices and codes, but it looks as if a branch circuit is tapped directly from the mains. Also, the ground (earth) appears to be switched and fused. Am I close?


"But the guy at Home Depot said it would work."
Re: Strange switch-fuse (UK) #111856 03/06/07 11:25 AM
Joined: Jul 2004
Posts: 783
LarryC Offline
Someone using a 3 phase fused switch for a existing single phase installation, while adding new wiring that used the "Harmonised" color codes?

Re: Strange switch-fuse (UK) #111857 03/06/07 11:45 AM
Joined: Sep 2005
Posts: 97
johno12345 Offline
Is this something to do with lighting? The connector at the top left is usually neutral, it seems to be a single phase supply with fused LNE and the neutral connector for some sort of switchwire junction conneciton?

Where did you find this?!?

I took my time, I hurried up, The choice was mine, I didn't think enough
Re: Strange switch-fuse (UK) #111858 03/06/07 01:15 PM
Joined: May 2005
Posts: 54
britspark Offline

and i thought i had seen it all !!!!!

oh my what a mess, please explain what the blazes is going on in there>

i hope you have removed this obvious mistake!

Oh and another note, we start a remodel of a night club onthe 19th march, will get some photo`s, you wont believe how is wired!!


Re: Strange switch-fuse (UK) #111859 03/06/07 04:38 PM
Joined: Jan 2007
Posts: 38
TrimixLeccy Offline
I like that!
Option 1) There does not appear to be a feed into lhs knife switch, but a lot of wires going into the top so, this could be a 'parking terminal'. Too many earth wires so middle one is an earth 'parking terminal', hang on a minute, got it now, isolator for Mother in Laws new massage chair! [Linked Image] I would love to get my hands on this and find out 'what it all does'
I am guessing that it is a factory handymans botched attempt at wiring a machine that needs a 3ph supply, but at least he sleeved the cpc!! where is it????
This could go on a long time

Re: Strange switch-fuse (UK) #111860 03/06/07 06:36 PM
Joined: Apr 2006
Posts: 233
Kenbo Offline
It looks to me to be a three phase supply. Red (not shown)yellow, blue 6mm?

Four twin and earths looks from here to be both 2.5 and 1.5mm being used to take away a three phase supply Black on the blue phase, Red on the red phase, and yellow green on the yellow phase. Cant see why they have reds and yellow greens on the earth terminal.

Totaly wrong but can see what he has done. Recon this was a handyman in a small industrial unit fitting small lathes or three phase lights.

Would love to have seen this on a thermal imaging camera bet the yellow green glowed like a christmas tree.

What is in those rewirable fuses tin foil?


der Gro├čvater
Re: Strange switch-fuse (UK) #111861 03/07/07 03:11 AM
Joined: Sep 2005
Posts: 97
johno12345 Offline
I think I can almost see what is occurring here.
The feed, possibly SWA enters at the bottom as it should and is connected Red, Yellow, Blue. in the standard arrangement. I think, however, that the red is phase, the yellow is earth and the blue is neutral. There are a number of single phase circuits fed from here in what looks like twin and earth.

The top left terminal block, usually for the neutral connections is being used as an earth terminal. There is a red from the centre fuse to this and another red from this to the casing. The only green/yellow in here feeds the grey t&e.

The other 3 T&E are connected up to the top of each fuse. The grey T&E is slightly more difficult to see, it looks as if the phase and neutral go below, possibly connecting to the live side.

I would guess that this is installed in someones garage made from bits from work and is being used as a consumer unit.

What size are those Kantark fuses? The whole enclosure looks a little on the smaller side. Is it 20A?

I would also hazard a guess that the fusewire is just a few strands of copper [Linked Image]

I took my time, I hurried up, The choice was mine, I didn't think enough
Re: Strange switch-fuse (UK) #111862 03/07/07 10:57 AM
Joined: Aug 2001
Posts: 7,520
pauluk Offline OP
O.K., first of all this isn't one of my jobs -- I came upon this photo on one of my occasional trawls through a DIY forum for anything of interest.

Apparently the incoming feed which we can't quite see is 3-core SWA (armored) cable, so presumably this isolator was originally used to feed some sort of motor-driven equipment (delta connected, no neutral). The angle of the photo has completely hidden the red conductor entering the left-hand main.

At some point an enterprising DIYer has converted the old 3-ph feeder to single-phase and this is the result. New connections are now line on red, neutral on blue, earth/ground on yellow. The block top left which should be the neutral (if needed) is being used as an earth block, with one red wire linked down to the proper earth terminal bottom right and another red wire linking to the top of the central fuseway.

The left-hand T&E cable exiting at the top has its neutral (black) connected directly to the incoming neutral. The line (red) from the cable can be seen dropping down between the first and second fuseways, and although we can't see it any further, I would assume it's connected into the left-hand main so that this cable is not controlled by the switch.

According to the sparks who founds this during an inspection, all three fuse carriers were still fitted with 30A fuses.

I don't know whether the armor of the supply cable was still grounded or not. If so, then the central switch-pole and fuse would be bypassed, but if not, then we have not only a fused neutral but also a switched and fused earth! [Linked Image]

I can't find the original thread in which this appeared, but I'll try again and post the link if I can locate it.

For our North American friends, here are some pics of a similar MEM isolator that I removed recently:

And in case there is still any confusion about the colors, there are no new "harmonized" cables involved in this instance. The colors you would expect to find in a unit like this are:

Phase A = Red
Phase B = Yellow (or white if pre-1965)
Phase C = Blue
Neutral = Black
Ground = Green or green/yellow

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