Feed for new DB in comm. unit

[Amp David]

Pricing up a little job to install a new sub DB in a smallish commercial unit. At the minute they have just one DB, which was put in when the unit was built, so its only an 8 way 3PH. Everything is taken from it, lights, sockets, office, 5 bits of 3PH gear etc, with some MCBs having 2 or even 3 circuits taken from it.

As the company are looking to invest in more equipment shortly, I suggested putting in a bigger DB, maybe a 20 way, to allow for future expansion and to take away the doubled up circuits of the main DB.

My aim is to free up a way in the main DB to feed the sub DB with a 63amp breaker, nice and easy and means not having to split tails and squeeze some henleys onto an already tight meter board. Just curious to see how others would approach it, regarding protection of the sub main.

 

[telectrix]

is the new sub going to be 3 phase or single?

 

[Amp David]

Oh yeah sorry, 3 phase

 

[Silly Sausage]

If you can get access during the day when they're not working, I'd replace the original board with a bigger new one. No sub main and it'd look better.

 

[telectrix]

good idea, then you've got a spare board for the next job.

 

[Amp David]

Was planning on positioning the sub board more centrally to all the equipment to reduce the length of any new circuits added

 

[malcolmsanford]

That is how I would do it as well Dave, First off mate what is the loading on this new equipment as 63 amp per phase is a fair amount for a smallish commercial unit.

 

[telectrix]

i'd feed the new sub in 16mm SWA, size breaker to suit load, max. 63A. sounds good.

 

[Silly Sausage]

Was planning on positioning the sub board more centrally to all the equipment to reduce the length of any new circuits added

Aye, but if you change the board, then if you get the job to run new circuits, you'll have longer runs, more work & more cash...:wink_smile::wink_smile::wink_smile:

 

[telectrix]

Aye, but if you change the board, then if you get the job to run new circuits, you'll have longer runs, more work & more cash...:wink_smile::wink_smile::wink_smile:

and higher Zs readings

 

[Amp David]

Aye, but if you change the board, then if you get the job to run new circuits, you'll have longer runs, more work & more cash...:wink_smile::wink_smile::wink_smile:

Thats one way to look at it yeah for sure, but would rather design it so that future additions can be done for reasonable costs, rather than throwing money at cable that might not have been needed.

Must be to honest:aureola:

 

[Amp David]

That is how I would do it as well Dave, First off mate what is the loading on this new equipment as 63 amp per phase is a fair amount for a smallish commercial unit.

TBH not 100% sure at the moment regarding the total loading, but will know on Tuesday once i've been to see what gear they have.

Its not going to be anywhere near 63amps, but just using this to start of worst case and all that

 

[Silly Sausage]

Your desire not to rip off customers is admirable.

 

[Amp David]

Thank you Archy!