Isolation & Protecion

[SpannerSpark]

Hi,

I have been made aware of a 1-phase circuit run from a 3-phase board, in SWA to a new CU powering a large extension room. Apparently the 1-phase has been spurred off directly from the supply with no isolator or protection. i havent seen the install yet, but can anyone recommend a suitable isolator/protection combo (i.e. switch/fuse or similar?) ideally 100A.

does this look ok? unsure of SWA rating yet, will adjust fuse as reqd

100A fused switch, Moulded White control gear fused switch up to 100A [800KMF] : Sparks Direct, Lighting and Electrical Wholesaler

tks

 

[JD6400]

Hi SpannerSpark , i think i used one of these about 8 years ago and found no way of making off the swa so had to use a metal adaptable box / DP henly block and come out in tails .
From memory there is bugger all room in it either and you need a shrouding that comes as a extra ?
You are best of with a proteus switched fused isolator from cef or even a proteck one from Denmans they are both cheapish and in my opinion 100 x better to work with .

 

[Jimmyb]

dont forget if main fuse is 100A then you cant fuse @ 100A again

 

[andrew692003]

800 KMF's are a handy, less expensive isolator for doing that type of job but as the above poster states little way of terminating the armour. In the past I have used these earthing and bonding to bond the armour and then tail into the isolator.

Not sure what you guyz will think of that method tho!

 

[JD6400]

dont forget if main fuse is 100A then you cant fuse @ 100A again

Well you learn something new every day , whats that about then ?
At the risk of me sounding like a pratt !

 

[JD6400]

800 KMF's are a handy, less expensive isolator for doing that type of job but as the above poster states little way of terminating the armour. In the past I have used these earthing and bonding to bond the armour and then tail into the isolator.

Not sure what you guyz will think of that method tho!

You bad boy , you will set them off now !:73:

 

[Jimmyb]

Its because of Discrimination between your fuse and the supplies fuse, pain in the arse for me alot cos i end up having to fuse down to 80A for log cabin then the customer says ive bought a 10.5kw and decided to use an electric hob instead of gas

 

[JD6400]

Of-coarse !

 

[andrew692003]

You bad boy , you will set them now !:73:

Ha I know but sometimes needs must!! Not ideal at all as I said but can be a handy....sometimes!

 

[johnboy6083]

if you must terminate the armour other than in a gland, then the best way is to use a roll spring, such as those found in jointing kits. they apply constant pressure, and will not deform the cable. A tenby ias not a good idea. We all know how easy it is for them to come loose on a solid pipe, nevr mind a cable!

 

[mechelec]

800 KMF's are a handy, less expensive isolator for doing that type of job but as the above poster states little way of terminating the armour. In the past I have used these earthing and bonding to bond the armour and then tail into the isolator.

Not sure what you guyz will think of that method tho!

I'll tell you what I think and that is that your method is rough, unproffesional, unreliable, against 17th wiring regs and not using the clamps for the purpose they were designed for. This sort of bad practice I was tought as an apprentice to not do but was of course shown the correct way.

 

[Amp David]

SWA terminations should be in a suitably sized gland.

Get yourself a WYlex switch fuse Wylex 160CM Metal Switchfuse With 60A Fuse [160CM]

Why do you need an 100amp too?

 

[SpannerSpark]

SWA terminations should be in a suitably sized gland.

Get yourself a WYlex switch fuse Wylex 160CM Metal Switchfuse With 60A Fuse [160CM]

Why do you need an 100amp too?

All, thanks all for your input...always nice to start an argument and then stand well back

As per my query unsure size of SWA and appropriate fuse rating to fit, to protect the cable yet. just said 100A so i can fuse up to that if reqd (its a very big room, complete with own kitchen, toilet, air con, socket rings etc.)

understood re discrim for fuse.

thats certainly is a good price for the wylex switch fuse. I think i will go for that.

I forgot to say in my query that i never terminate SWA without the proper glands. If using the 800KMF I was intending to to fit a small metal adaptable box immediately beneath it, terminate the SWAs with glands into that and then run the made off ends to the switchfuse, through grommetted holes of course between the two boxes.

tks

 

[SimpleSimon]

So when you say spurred off.... It's not coming off an MCB in the three phase board?

Just to throw something in, can't you just terminate the armour with a gland and banjo and take fly lead to the earth bar? Thought that was acceptable too?

 

[Knobhead]

If your going to use an adaptable box bear in mind eddy currents where the cores pass through the box. They must pass through in pairs.