Maximum Demand Question

[Essex1]

But if you do not limit it in some way then you risk blowing the main head and that would be even more embarressing.

I would give the client two options:

1 - fuse down to 80A to provide diversity between the head and the DB and limit the current available.

2 - upgrade to a 200A supply and do the job propely.

Two very different prices there. Detail the pros and cons in the quote then if it does blow. You can hold your head high.

 

[apprentice87]

Mr Essex talks a lot of sense there....

You are going to have to provide overcurrent protection for your submain anyway, so could you fit one of these...

http://uk.rs-online.com/web/p/mccbs/4548073/

You are able to vary the trip current from 80A to 100A by turning an adjuster, and in the same way you can change the "instantaneous" trip values from about 6x to 10x the rated current of the thing, so it is like being able to go from a "B" curve to a "C" curve by turning a screw!!!!

They do different models though, an 80 - 100A and 60 - 80A so you could have a think and then choose the one you think best...

john..

 

[Dairyspark]

They won't be connecting any of the yard equipment to it as the welders are in a different location (closer to the boats) as is a compressor and 110v supplies for temp lighting etc.

I'm currently looking into mobile or transportable units lol

However while I'm on the subject, what's the difference between having one main 30mA rcd and several individual rcbos?

There will also only ever be one 63A used at a time as the 2 boats we get (one 230 one 400) can only be taken one at a time and are only ever up for short periods of time (1-2 days as apposed to several weeks for other boats)

Looks like it'll be 63+32 = 95A

 

[Essex1]

Think about a house. Then ask yourself that question regarding the RCDs again.

 

[Dairyspark]

I think your pointing me towards if one boat develops an earth fault which trips the main rcd then power is lost to the whole board. Where as if each circuit is individually RCD protected then only that circuit will lose power.

 

[Doc Hudson]

It would be more compliant with the regulation that says you should minimise inconvenience due to a single fault. Ideal world costs permitting every circuit should have it own dedicated shock protection device. 

Doc H

 

[Dairyspark]

Be gentle about the critisism

 

[Essex1]

Well done.

A few things I would change mate.

1. The SWA in the top left - I think this could be made to look neater.

2. I would have also liked to have seen an isolation point that was not the OCPD in the DB.

Oh - and good on you posting a picture. Takes some balls does that.

 

[Andy™]

not a bad job. only additional thing i would have done is a label on each outlet with its DB & circuit number, but it looks like that may be in marker?

maybe put the trunking lower and save on the conduit?

 

[Dairyspark]

SWA in top left was already there, the board was put in place 2 years ago (I think) and I didn't have enough time today to make it look better.

Each socket will be marked, I ran out of time, spent the first 2 hours of the day waiting to be allowed to turn it off lol.

The trunking was also at that height previously so it had to go back in the same place, didn't want to put the sockets any higher and the 2 63A ones had to go at the bottom for space lol.

And I think it's good to post pictures of what I've done, I may think it looks amazing but I like other people's opinions too.