What would be the effect of connecting a 22kW EV Charger to 3 phase supply with 30A fuses for L1,L2,L3, with a 40A RCCB for the EV Charger. The reason for asking is we already have a 3phase switch with 30A fuses not being used. EV is the only thing that will be using this.
Effect of 22kW EV charger connected to 30A 3 phase
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The effect is that it will most likely work if there are no other loads on the supply.
The reality is that's it's a poor design, as EV charging can be up to 32A, which is obviously more than 30A. This will result in those fuses running just above their rating, and getting rather warm.
The proper choice is to either change the fuses for a higher rating, or sling the old switchfuse away and fit something suitable for the new circuit.
The reality is that's it's a poor design, as EV charging can be up to 32A, which is obviously more than 30A. This will result in those fuses running just above their rating, and getting rather warm.
The proper choice is to either change the fuses for a higher rating, or sling the old switchfuse away and fit something suitable for the new circuit.
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Yes 22,000 watt/3phase/230volt = 31.88406 amp. Simple maths, it is unlikely a fuse will rupture, but clearly on the edge. I have never actually put a clamp-on on a phase wire, so no idea what it actually draws, it would be interesting to see.
This switch is an old ceramic with 30A fuse. The alternative is the replace the switch with 32A fuse but there is no isolator between the mains and the switch. Would it be okay to rewire the fuses with a 32A fuse wire?
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I would think that would contain asbestos, so clearly needs changing. The fitting of EV charging points is not a DIY job, from the question you are out of your depth, and you need to get some one in to do the work for you.
Have you looked at earthing requirements for the EV chargepoint?
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I had thought about mentioning that, but to be frank, I am not sure myself what is required, with TT easy, but today we have to consider TN as being TN-C-S as it can be combined and split anywhere, not just in the house, so unless the DNO have labelled it as TN-S we have to assume any TN supply is TN-C-S.
In theroy a wire made out of a metal like tin or tin alloy having a very low melting point, but there are adds for tinned fuse wire 30A, SWG 21 100g per reel. Convert to inches it says 0.032 and mm 0.813 so 25.4 mm to inch, and the match, however they should not match, as in inches it is thickness, and in mm it is cross sectional area. But internet hunt seems to say diameter of 0.9 mm is 32 amp.
However not sure I would want to trust that. I have seen fuse wire glow red then melt, I do not think tin glows red before it ruptures, so it would seem that was not proper fuse wire? If I want a 32 amp fuse, I want something like this
not taking a guess if I have the right wire.
FUSE WIRE 32 AMP 0.9mm 20 SWG Tinned Copper Wire 10meters - UK SUPPLIER | eBay
SWG Number: 20. Tinned copper wire finding many uses including board repair and shorting links on PCBs. Conforms to BS4109. TINNED COPPER FUSE WIRE. Conductor Make-up: SINGLE STRAND. 0.125MM 2.3.
www.ebay.co.uk
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Some may frown on doing it, but with the old Mem switch fuses you could bin the porcelain fusewire holders and plug in the newer Mem Eaton Plastic Hrc fuse holders that take 32a SB3 HRC fuses
You can still get them https://www.edwardes.co.uk/products...e-32a-exel-plastic-fuse-carrier-with-hrc-fuse .
However one needs to bear in mind the likely presence of asbestos flash pads behind the rewire-able carriers and ensure that they are dealt with in a suitable manner
If they match the 'Red Spots' I expect I still have some I haven't chucked out yet.
Almost unrelated to your question, but it's worth checking which EV (or EVs) you plan to use with your new charger as relatively few actually support 22kW charging these days. By no means all of them support it and a surprising number are limited to 7kW single phase or 11kW single phase. Over our two years of EV usage, our charging model has also changed dramatically as we're using Intelligent Octopus Go which often charges at lower rates for much longer periods if it doesn't need to charge faster.
That is true but the cost difference of installing a 3 phase vs single phase EVSE is insignificant.
If 3 phase is available, then a 3 phase EVSE should be installed there.
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