SWA Gland into plastic Consumer Unit

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I set myself up with a test rig to get my head around domestics electrics. All of this is working.

I now want to add a 25mm armoured cable and had some questions. The plastic unit does not have any round knockouts and I have been reading that it may be too flimsy for a SWA gland.

I have purchased this as my gland:

Got some plastic cleats and will safely terminate into one of these:

This appears to have a 25mm knockout for the other end of the SWA gland. I am hoping it will be robust enough once the cable is cleared to my board.

How do you suggest I handle the Consumer Unit end? Do I need an additional box and which drill bit do I use for a whole through the CU?

Also, in terms of breaker size, my reading suggests that this cable is rated at 125amp but my main fuse is only 100amp. Clearly this is a test scenario and I do t have any planned loads. 40amp seems to be the highest breaker size. I assume it’s either that or I could use a Henley Block and take it out just after the main fuse. Not something I can simulate here but is the broad understanding correct?

Thanks in advance.
 
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That's some pretty big SWA, unless there is a long run involved and it's needed for volt drop it would be rare to use a SWA that big on an outgoing circuit on a domestic CU.

While the terminals on MCBs are quite big, I think the neutral and earth bars are only designed for sizes up to 16mm² it's possible to make a fork in the end of a conductor and put it in two adjacent terminals, but it's a bit of a hack.

In terms of drilling big holes in thin materials either a holesaw or a step drill are your two main options.
 
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That's some pretty big SWA, unless there is a long run involved and it's needed for volt drop it would be rare to use a SWA that big on an outgoing circuit on a domestic CU.
It's an offcut I managed to get my hands on and wanted to use for my test rig. Out of interest, what's the standard size for an EV charger cable?

While the terminals on MCBs are quite big, I think the neutral and earth bars are only designed for sizes up to 16mm² it's possible to make a fork in the end of a conductor and put it in two adjacent terminals, but it's a bit of a hack.
In my case, should I terminate the SWA into a metal box and then take a 10mm into the CU? I appreciate that my MCB would then have to be rated down to protect the 10mm.
 
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Wonder if the op really means 25mm swa or has he just measured the diameter?
In general, a very valid thought/question.

However, and by pure co-incidence, I don't think it makes any significant difference in this particular case, since I think you'll find that the overall outside diameter of 3-core 25mm² SWA is usually about 24mm (... and far bigger than one would expect to see in any domestic installation)!

Kind Regards, John
 
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Wonder if the op really means 25mm swa or has he just measured the diameter?
This is where I am getting this size from
1655386661032.png
 
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This is where I am getting this size from
That's clear enough - but, as I just wrote, by pure co-incidence I think you'll fins that the outside diameter of the whole cable is probably around, or fractionally under, 25mm.

However, as said, that cable is probably larger than one would usually expect to find in a domestic installation. In many cases, the DNO's supply cable to the entire installation will be smaller than 25mm².

Kind Regards, John
 
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What size cable is typically used for an EV charger?
Also, for my practice install, which type of adaptable box can I use for the SWA Gland and would a 50amo breaker be the most sensible choice for this?
 
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What size cable is typically used for an EV charger?
Also, for my practice install, which type of adaptable box can I use for the SWA Gland and would a 50amo breaker be the most sensible choice for this?
Obviously it depends on the design, but typically 6mm^2 cable (or 10mm^2 at a push). Certainly not any bigger than this as you will not be able to terminate it in the charge point. (Even 10mm^2 is a real struggle with many brands.)

Unless you're going to run into a rotary isolator first.
 
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What size cable is typically used for an EV charger?
Dunno - not something I've ever had to deal with (and maybe never will!) - but, as I said, it would not make sinse for it to have a larger CSA than the DNO's supply cable. Intuitively, 25mm² sounds way OTT to me.
Also, for my practice install, which type of adaptable box can I use for the SWA Gland ...
I would presume that any box large enough to accommodate the (fairly large) gland would do.
and would a 50amo breaker be the most sensible choice for this?
Depending on whether or not it's buried, and whether it's 70° thermoplastic or 90° thermosetting plastic, the CCC could be anything from about 100A up to nearly 120A, so breakers with much higher rating than 50A would be adequate to protect the cable. However, if you were going to use 'over-sized' cable, it would probably make sense to size the breaker to be appropriate (a little over) the current required by the load - and that would obviously depend upon the actual EV charger (or whatever).

Kind Regards, John
 
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I would presume that any box large enough to accommodate the (fairly large) gland would do.
I am guessing this has something to do with my ridiculously large cable but there aren't any metal boxes in Screwfix/Toolstation that have a 25mm knockout. Can I use this and drill the 25mm hole for my SWA gland using a holesaw?

 
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What size cable is typically used for an EV charger?
Also, for my practice install, which type of adaptable box can I use for the SWA Gland and would a 50amo breaker be the most sensible choice for this?
For a 7.5kW home charger, the manufacturers usually recommend at least 6mm² to reduce losses in the cable. I used 10mm² for mine; even then, it still gets warm to the touch.
 
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I am guessing this has something to do with my ridiculously large cable but there aren't any metal boxes in Screwfix/Toolstation that have a 25mm knockout. Can I use this and drill the 25mm hole for my SWA gland using a holesaw?
I don't whether any widely-available boxes have 25mm knockouts but, yes, provided the box is large enough, you can obviously just make a 25mm hole in it yourself (by whatever means).

P.S. Although I've never had a need to use one, so don't know the answer for sure (but I'm sure that Mr Google would know!). I would have guessed that a gland for 25mm² cable would require a hole appreciably larger than 25mm in diameter. Is that not the case?

Kind Regards, John
 
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I set myself up with a test rig to get my head around domestics electrics. All of this is working.

I now want to add a 25mm armoured cable and had some questions. The plastic unit does not have any round knockouts and I have been reading that it may be too flimsy for a SWA gland.

I have purchased this as my gland:

Got some plastic cleats and will safely terminate into one of these:

This appears to have a 25mm knockout for the other end of the SWA gland. I am hoping it will be robust enough once the cable is cleared to my board.

How do you suggest I handle the Consumer Unit end? Do I need an additional box and which drill bit do I use for a whole through the CU?

Also, in terms of breaker size, my reading suggests that this cable is rated at 125amp but my main fuse is only 100amp. Clearly this is a test scenario and I do t have any planned loads. 40amp seems to be the highest breaker size. I assume it’s either that or I could use a Henley Block and take it out just after the main fuse. Not something I can simulate here but is the broad understanding correct?

Thanks in advance.
If you're trying to learn how to do this work, Why sre you talking about adding a totally unnecessary additional metal box?
There are other products besides brass glands.
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