sparkies i need your help

[harvey639]

ok so im fed up with replacing the fuse in my welders. i want to have one 32A socket and two 16A sockets installed in my workshop. the only problem is the main panel also supply's the stables as well. there is a 40A breaker that used to be for the stable heaters that no longer exist. would it be possible to up rate this and the main breaker for the panel (100A at the min) and run an length of cable to my workshop and have a garage consumer unit fitted that would have 2
32A breakers fitted one for my mig 32A and one for two 16A sockets? i was going to buy all the bits and have an electrician come and hook every thing up. what do i need? and is it possible?

 

[harvey639]

just been thinking will i need a bigger panel?

 

[Premiershipman]

Are all the sockets going to be used aT the same time ?

The reason i ask is that i have a 32amp rcbo in my consumer unit, but it goes to an isolator unit and then i have two sets of cabling frm the isoator, one going to a 32amp socket for the mig and one set going to a 16amp socket.

This way i can use the 32amp socket or the 16amp socket depending on whether i am mig welding or using the tig welder.

Just an idea.

Shady

 

[brightspark]

thats an old obsolete board . just get rid of it and replace it with a 17th edition twin rcd board. u can get new ones for 65 quid and start from there. u will probably need the main earth and bonding upgrading anyhow 16 mm earth on mains and 10mm to gas or oil supply if u have it and water . and run a new feed out to a 3 or 4 way unit in your garage

 

[madkayaker]

That is an old board! without changeling the board I would live with a 40amp supply as your unlikely to be running loads of stuff at once and exceeding that. What kit are you planing to use? You will not be able to get a 100amp breaker for the fuse board as the main fuse for the supply is Probily only 100amp so you would have no diversity between the two. The next size fuse down is 80amp but if you we're pulling that kind of load in the workshop and the load from the rest then you might blow the supply fuse which can be problem as the DNO can get hard work when you ask them to change the fuse (it's illegal under the supply and continuity regs for a sparky to do it but many do)

 

[brightspark]

That is an old board! without changeling the board I would live with a 40amp supply as your unlikely to be running loads of stuff at once and exceeding that. What kit are you planing to use? You will not be able to get a 100amp breaker for the fuse board as the main fuse for the supply is Probily only 100amp so you would have no diversity between the two. The next size fuse down is 80amp but if you we're pulling that kind of load in the workshop and the load from the rest then you might blow the supply fuse which can be problem as the DNO can get hard work when you ask them to change the fuse (it's illegal under the supply and continuity regs for a sparky to do it but many do)

the biggest breaker that will fit in domestic boards is a 50 amp so your stuck with the 40 amp if the board isnt getting changed . rcd protection is needed and earth bonding for any upgrade of the system. the 40 amp mcb in the old board is not rcd protected

 

[madkayaker]

you can get 63A breaker or as a separate unit 80A fuse switch. the 40A is currently not RCD protected your correct but a RCD unit next to the board is not a big deal or great expense.

 

[brightspark]

you can get 63A breaker or as a separate unit 80A fuse switch. the 40A is currently not RCD protected your correct but a RCD unit next to the board is not a big deal or great expense.

by the time you have spent 25 quid fitting an rcd under the db in line or seperated and fitted an 60 or an 80 amp switchfuse and have to fit an rcd and uprate the cable for 60 amp as its probably only got a 6mm feed anyhow is the bodge worth it

 

[madkayaker]

You missing what I said. I said leave as is or if the op wanted a bigger supply these was available.

 

[urban]

This is a case again of not enough info to make a good assessment of what's actually required...

Will you be using the 32A and the 2x16A sockets at the same time or 1 at a time?

What is the size and type of cable (PVC or armoured or another) currently being fed by the 40A breaker or do you intend to run a new cable to supply the sockets?

How long is the run of cable that is already there or that will be installed to these sockets?

What environmental/thermal effects will the cable be subjected to throughout it's existing run or the run if you intend to install a new cable?

What are the current earthing/bonding arrangements of your current installation?

Electrics aren't worth messing with, you're always better upgrading to the current protection/equipment level and though your CU is miles better than some and the old rewire-able fuses that are still knocking around a plenty these days if you upgraded you would have the capacity to make additions in the future on top of the one you're currently talking about.

 

[harvey639]

no they wont be all uses at the same time, however both the 16A will be if im using my plasma. so only 34A at a time not 68A dont want to change the whole board so i guess the 40A beaker will be OK.
plany yo run my mig, plasma and air compressor.

i will be replacing the cable from from the board to a smaller garage consumer unit in the workshop with two 32A breakers one for the mig and two 16A sockets one for my air comp and one 32A socket for my mig.

 

[harvey639]

use one of these for the mig
http://compare.ebay.co.uk/like/261096590543?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar&cbt=y
and two of these
http://www.ebay.co.uk/itm/Rotary-Is...Supplies_ET&hash=item35b32827b3#ht_5355wt_906

fed by one of these but with the correct breakers

http://www.screwfix.com/p/mk-sentry...ng-_-MK Sentry 4-Way RCD Garage Consumer Unit

 

[wheresmejumper]

what are the mig and compressor rated to,max current?
cos if youre using the welder and the compressor cuts in unknowingly you could be constantly exceeding the 32/40 amps
if it is a possible scenario you would need a non priority unit to prevent this from happening

 

[urban]

If you're running in a new cable for the garage supply unless it is armoured or run at least 50mm deep in the wall or run on the surface (apropriate trunking/conduit) it will need to be RCD protected which would mean an upgrade of your current consumer unit or the installation of an inline RCD unit on the cable where it comes out from the consumer unit.

The size of the cable may most likely need to be 10mm squared to allow for thermal effects/volt drop (depending on the factors along the cable run).

The garage unit will be fine, but for the breakers you may find you're better with C or D type breakers. The built in RCD will most likely be a 30mA trip current and I have known these to trip with welders in the past so that may need upgrading to a 100mA current or replacing with a standard main switch but then apropriate measures will have to be made to protect the cable from penetrating mechanical damage etc (nails etc.) meaning it will have to be armoured or surface run in the appropriate conduit/trunking for the environment of your garage.

If you're using 32A MCBs in your garage unit I'd recommend 6mm cable though you may be able to get away with 4mm depending on factors mentioned previously, 4mm will be easier to terminate in your radial of 2 x 16A sockets.

 

[harvey639]

was planning to use armored cable. mig is rated at 32A and the compressor is rated at 16A

 

[wheresmejumper]

you could well run into that situation so,but a non priority unit isnt cheap

 

[urban]

Armoured eliminates the need for RCDs for the sockets you are using so feeding it from the existing consumer unit 40A breaker would be fine providing your earthing/bonding are up to spec.

Don't forget if there are any incoming services (gas, water structural steel work etc.) coming into the workshop that aren't already bonded these will need to be as you are introducing an electrical supply to that workshop.

 

[urban]

You could turn off the compressor while you are welding to prevent overloading and subsequent tripping of the MCB.

 

[wheresmejumper]

you could,but you will forget,which is why they are recommended

 

[madkayaker]

The RCD issue is irrelevant as the installation if for use and under control of a NORMAL i.e. not electrical competent person so needs to be RCD protected irrelevant of the installation methods mentioned above