Adding an furth 63A load

[uksparks]

Hi,

What are your thoughts on adding a further 63A load to this board? It will be using 63A too, not just a few amps of it as its a for a twin car charger.




looking at it, theres a max load of the following if everything was maxed out.

L1: 126A
L2: 193A
L3: 211A

I need a 63A single phase supply, so my gut instinct says put it on L1, but to you feel im adding a lot of extra load to the board? I know its not a huge amount but just wondering what your thoughts were?

Obviously taking diversity into account etc, its not over the top, its only an office. The two 63A supplies on L2 and L3 on 35 and 36 are not in use at the moment but will be shortly.



The other part of the issue is, getting armoured cable out of the wall, its got to come from about 2.5 meters up the wall, down then into the ground. I don't really know which way to tackle this as I want it to look really neat and tidy for the customer. The cable is then going into the ground outside.



I can get away with 10mm SWA to feed the charger unit, but not 100% sure the best option really to get it looking nice on the wall, then theres this bit at the bottom at juts out.

I did look at running non armoured cables to an adaptable box on the outside then glanding the SWA to that and straight down, but ideally i don't want to use an RCD / RCBO to feed it as the unit has two RCBO's built into it.

 

[Engineer54]

If those other 2 63A breakers are also going to be loaded up, then your getting pretty close to maxing this 3 phase 100A DB for real ...lol!!

 

[uksparks]

Well they are only for two offices, both are about 10m x 6m, so not huge, so unless they are growing something, then I doubt it.

 

[Deleted member 72666]

It's hard to tell without measuring etc but from what I see L1 is the least loaded phase, if the last 2 ccts are only small offices then can't you fuse them down to 32amp then that way it'll go a long way to stop them being abused in the future by numpty sparks who'll see them as 63 amp available load.
Edit:
What are the numbers referring to written in biro on the left hand side, are they the actual circuit numbers?

 

[uksparks]

To be honest I have no idea, thats all written on a piece of plasterboard propped above the distribution board... not very good for a new install is it, i dread to think what it will look like inside.

Yes thats not a bad idea, I could drop them down to certainly 40A breakers which would assist, or like you say 32A, that then frees up a bit, to be honest, i bet they are only pulling less than 10A anyway, ill have to measure it.

What do you think about the outside bit? I don't know what to suggest.

 

[Plonker 3]

Why would swapping existing MCBs help? The current drawn will still be exactly the same.

 

[Plonker 3]

If the cable is being buried then SWA externally certainly, to get it to ground level use galv trunking as that wont look out of place attatched to the outside of that type of building.

 

[Guest77]

Re: Adding an furth 63A load ------------ ??? perdón

 

[davesparks]

Eddy currents anybody?

 

[Fin170]

Why would swapping existing MCBs help?

Because the ones on the left side of the board are all clearly drunk



Is the charging point going to have its own earth rod? (more out of interest than anything)

 

[ferg]

Eddy currents anybody?

Oh ye of little faith.

 

[cdavies33]

Eddy currents anybody?

Yeah, seen it. 2 tails through a 25 mm stuffer. Board schedule written on a white board. It's been wired by a chancer for sure

 

[Bait Account]

UK have u applied diversity to that lot? As for the bit outside bung a bit of metal top hat over the swa and it'll look sweet.

 

[Guest55]

having spare capacity in the DB is only half the story , you need to check the potential of whats upstream.

and i'd use 50mm tray on top hat brackets for the cable run down the side of the building then cleat along that row of bricks above the gravel , with strip grommet and silicon for the wall penetration.

 

[davesparks]

Stick a data logger on it for a week or two and see what the load really is!

 

[uksparks]

having spare capacity in the DB is only half the story , you need to check the potential of whats upstream

Such as? That's the board for the whole building...

 

[Guest55]

Such as? That's the board for the whole building...

the dno fuse rating for a start - a 100A cut-out might not have a 100a fuse in it.

and although it looks like that DB might be fed with tails straight from the meter , if it was a submains you'd need to check its capacity too.

 

[uksparks]

the dno fuse rating for a start - a 100A cut-out might not have a 100a fuse in it.

and although it looks like that DB might be fed with tails straight from the meter , if it was a submains you'd need to check its capacity too.

Yes totally agree, I can get confirmation of the fuse sizes from WPD, ill get them to look.

 

[Stu1312]

Have you had a look on the meter for what the loadings are? Depending on how it's setup an EDMI meter is capable of recording maximum demand and it's normally on the display this would give you a good idea of how close to the supply capacity they are

 

[uksparks]

Ah i didnt realise that, ill have to look.

 

[Stu1312]

If you can't see anything useful when cycling through the display, hold the display button down for a few seconds and it should go on to the set B display, this normally has all the instrumention displays on. Can't guarentee what will be on the display as different meter operators set the meters up in different ways.

 

[uksparks]

Ok thanks, I appreciate the pointers there, I think L1 is the best bet, like I say, it's unlikely they are even using 10A in reality, its only a dozen computers etc, nothing too much.

 

[davesparks]

Ok thanks, I appreciate the pointers there, I think L1 is the best bet, like I say, it's unlikely they are even using 10A in reality, its only a dozen computers etc, nothing too much.

Don't guess it!

Get it wrong and overload a phase and you could see this business shut down for a few hours, how much will that hurt your insurance?

Does the new load have to be a single 63A supply?
And does it really draw the full 63A?

 

[uksparks]

It's ok I won't be guessing, just on the face of it I would say L1 is more suitable.

Yes it's having two electric cars plugged into it which both use a 32A charge lead, so yes the load will either be 32a or 64A.

I did ask if it can be on two phases but it can't, I would have to put two posts in.

 

[davesparks]

How much current actually flows through that 32A charge lead?
How long is the charge cycle?
What is the likely usage pattern of the charger?

 

[uksparks]

It uses the full 32A for about 4 hours

 

[ImpededLoop]

Yes it's having two electric cars plugged into it which both use a 32A charge lead, so yes the load will either be 32a or 64A.

If this is the case, a 63A breaker would be too small. However, I doubt each charger uses the full 32A. What's the kW rating of the units?

 

[uksparks]

The manufacturer states that it needs to be on its own 63A MCB, I don't know how much it draws exactly but I do know that they do pull 32A when charging, maybe when both cars are plugged in, it drops the power output down slightly.

 

[uksparks]

I spoke to the manufacturer this morning and they can do it as a three phase version so would be able to split it over the three phases yet still have a single phase output of three phase output.

 

[davesparks]

I spoke to the manufacturer this morning and they can do it as a three phase version so would be able to split it over the three phases yet still have a single phase output of three phase output.

Bingo! Less load on each phase, smaller cable, cheaper and easier to route and bend neatly as it comes through the wall.

 

[uksparks]

I need to speak to them and get the full details on how much per phases bug would assume it's going to be around 22A per phase so can drop the cable down a size bug at the same time will need to possibly look at either 4 core or 5 core depending on how tight it will bend. I'll go and get a bit and see what I think.

this may possibly solve the problem in another way though.

 

[uksparks]

I could probably get away with 4mm now instead of 10mm, that's quite good really.

 

[davesparks]

You'll get it down by more than one cable size, it'll probably want a 20A TP, or maybe 32A but unless it going far 4mm should be good!

I think you can definately say you'll need 4 core, unless it's operating without a neutral!

 

[uksparks]

It's got to go about 14m so without doing the calcs 4mm should be fine, yes 5 core should do it nicely, I'll order a few bits so I can play around with it and see which I feel is best suited.

They said if I go with three phase, I can either have a three or single phase outlet, but it changes which type of lead you need so think I'll still go single phase but with with three phase supply, that way they can use the same charge leads at home too.

Once I have done it, after Christmas now due to manufacturing of the unit, I'll take photos for you to see.

 

[Plonker 3]

Why use 5 core SWA? The armourings should be more than adequate for a CPC .

 

[davesparks]

Order a few bits to ply around with?
Wtf is that all about? You calculate the cable size required and then use that size! 4 cores for TPN, 3 for TP and 2 for SP

 

[uksparks]

Order a few bits to ply around with?
Wtf is that all about? You calculate the cable size required and then use that size! 4 cores for TPN, 3 for TP and 2 for SP

All i meant was I was going to pick up a bit of 4mm 4Core to just see how much it will bend, I need to know as I will then either do that with a through gland or use an adaptable box. I know which cable i will need depending on which route I chose to go down, I would like the TPN route, but the unit may be a lot more expensive so would have to check with the customer, It may be the same, or just a trivial difference i can absorb.