What should I budget for getting a workshop wired up?

To JoeT (OP),

Best way to go about this is to decide what you want and where you want it, get together a list of materials, price it at screwfix, and add 10% for contingency, then find a local electrician (by recomendation is the best way, ask about) and get a price for the installation on the basis that you will supply the materials to his requirements, and he provides the labour. Some areas have good electrical wholesalers who will sometimes (not often) equall or beat screwfix prices, iif there are , he will know them. If there is already a lighting circuit and a ring socket (two cables) in the building/room/garage you are using for a workshop you can extend these circuits for most uses. the welder needs a 30amp sub main running back to the mains position, and protection for this should be a fuse and an RCD as the current demand will trip most MCBs. Having said that I run my 180A mig on a 13 plug, which is what it came fitted with as new about 30 odd years ago, and I have never had a problem with it. Also please note that under the "revised" part P regulations a part P approved contractor now can check and test the work of others. Also be aware that some part P approved "electricians" have nothing more than a FIVE WEEK training course behind them (no apprenticeship or other electrical experience whatsoever) So beware.

I have jsut checked a recent bill from friday from my local wholesaler(Driffield electrical supplies) who does 50m 2.5mm t/e cable for £28-98 inc vat, the screwfix price is £31-53 inc vat, so it can be done!

Phil

The Sparks should have no problem adding in a sub main after the meter/main fuse as they just need to remove the main fuse, there is a debate by some as to the legality of breaking the seals but most suppliers accept the need.

All sub mains need a fused isolator for the meter tails to connect into with the sub main from that.

Cable size and type for the sub main will depend on location of additional CU and if the cable runs external the it will need to be armoured cable, a 6mm SWA cable would be capable of 60 amps but length will reduce that figure.

For welders or large power connections I would be inclined to use a separate socket industrial 3 pin type something like these **LINK**

Bob

Hi JoeT, re your picture, that is an early Chiltern or crabtree(?) earth leakage circuit breaker, when you press the yellow test button, it should trip. I only see one earth wire, there should be two, one going to an earth spike, and another going to the consumer unit to provide the installation earth, They work by sensing any current flowing in the earth wire and tripping if this current rises above a pre set level. If you cannot find the second earth wire, there are two possibilities

1) Your entire house is not earthed!!!

2) the installation has been converted to PME by the supply authority, but they have not put the PME sticker on the board.

I am guessing this pic is in a cellar, and the consumer unit is upstairs, can you post up another pic taken from a bit further back and including the meter and also one of the consumer unit. That is a very old fuse cut out, probably mid 1950s, nothing wrong with that, but you need to check your earthing !

Phil

Hi JoeT,

Your sparks won't have to work live, he would complete the installation , then turn off the ELCB and connect the new switchgear to the dead side of it, then switch back on.

Phil.

Hi Bob Brown,

Re breaking seals on cut out fuses. We were told at tech college that this came under the Electricity supply act 1922/3 which states that if you arrive at an installation and find it in a dangerous condition you may remove the cutout fuse in order to make the installation safe. In a situation where the only alternative to working live is removing the cutout, I remove the cutout in order to make the installation "safe" to work on. I haven't been challenged by any supply authority in 40 years. I have on occasion informed the supply authority and asked them to come and reseal, never had a problem there either. The folks who bleat on about it being illegal, are generally less well trained or less experienced than they should be. Of course if the equipment wasn't sealed, it would be easier to nick the electricity, and harder to prove as there would be no seal to tamper with, and it is "tampering with the seals in order to abstract electricity" that is illegal.

Phil

Hi Joey T

The double pole earth leakage circuit breaker in your installation is voltage operated and not current operated.

For several years this type has not complied with the regulations, it can act as an isolator but only to the rating of 60A.

Emgee

Hi Emgee

"For several years this type has not complied with the regulations",

This means nothing really, although you are correct to say it is voltage operated, not current. It complied with the regulations in force when it was fitted, if it is still in working order, that is all that is required of it. There is absolutely no requirement to bring installations up to compliance with modern regulations unless major works are undertaken or the equipment is faulty. There are still hundreds of thousands of this type of equipment in use, providing perfectly adequate protection provided they are tested by the householder (just like the RCD's are supposed to be). The IET will tell you that the more modern RCD's and MCB's provide better protection, but as I have said above, like this ELCB they do not fail safe, and therefore in the event of internal failure of the trip itself, the power stays on, and under the new system, there is no seperate fusing, only the cutout fuse at 60 to 100 amps. As an electrical engineer with over 40 years experience I do not consider this type of protection to be better, I find it to be much worse.

Thanks Phil, Glad you have explained what didn't happen to ME on Christmas day in 1979. Wiring was less than five years old and DID go through a 5 amp wire fuse. "Chandelier" was a glossed up term for a single ceiling rose and wire to a standard single bayonet bulb holder.

Regards Ian.

Hi Circlip,

I didnt say it didnt happen, what I was trying to expleain is that there is more to it than meets the eye, with wiring ony 5 years old that is even more worrying, thank the lord you are not there anymorre

Phil

Regarding the blown 60 Watt lamp failing and then the main fuse blowing. Whilst this is not a common occurrence it does happen. As the element/filament fails it shorts across the pair of leads within the glass envelope forming a short circuit. The old type of wire mains fuse ages, not all premises have cartridge fuses even today. I will explain, the piece of wire, warms,expands, warms again, cools etc and gradually its cross connectional area reduces and then its fails, often at the most inconvenient time. When considering the size of cable for a workshop installation don't forget that you won't be using all machinery at the same time so total load is different to load in use. Diversity !

An interesting aside. 6 students rented a house, on arrival one switched on the hall light, it didn't work, another tried the living room it didn't work either. They tried them all of the lights and non worked, this was on a Saturday evening, so they used their phone to call the supply company. When the man arrive he checked the mains and all was well and at first he was a bit confused. The previous students had collected a lot of failed bulbs and fitted them to all lamp holders before departure. Total cost £75 .

This is what happens when parents buy their kids Nintendo consoles for Christmas and not Meccano.

Nick

Interesting theory John, but I am very fa,iliar ith fuse fatigue, tht doesnt explain why the replacement fuse blew as well, unless it was also fatigued. Love te student tale!

Phil.

Hi Phil

With 40 years experience you should have identified the ELCB as a voltage operated type and not current operated.

Secondly if the installation had been converted to PME by the supply authority there would be a suitably sized earth conductor from the consumer unit connected to the neutral block, there is none showing in the picture.

I don't know any electrical contractors in my area who are prepared to install customer supplied materials for such a job, maybe where you are it is accepted.

Emgee

I think the installation is a TT system with no supplier earth but an earth spike and an earth cable back to CU then on to the ELCB hence the single earth wire in the picture.

This system is common where the incoming cables are overhead.

As the garage is internal then it should not present any problems adding a sub main and I doubt the earth system will require any changes. If the garage was external then a separate earth spike would be required.

Not forgetting that cable sizes are now larger than they were in the past and that includes earth conductors.

Bob

I'm having a bit of trouble keeping up with the speed of this thread, but, yes Bob & Emgee, the property does have incoming overhead power cables.

Cheers Bob - yes I was planning to use industrial connectors for the higher current supplies. The welding college has some sockets with a built in rotary switch that supposedly don't let you remove a live cable, or plug into the socket when it's 'on', but from the red colour on the plugs and the warning labels, I guess this might just be because they're 400V 3-phase. I will have a look for single phase 16/25A 230v ones.

Joe, I know those sockets and have seen them for 240v 16A with RCD so assume they are still available, the only issue I find with them is the number of people who can't get their equipment to work, the turning of the plug is not obvious.

Baldric

Hi Baldric - no, the ones I have in mind have a very obvious 50mm+ diameter round on/of switch - up for off, right for on IIRC. I have seen the ones with RCD's in them on the Screwfix site - I didn't realise that they had the issue with rotated plugs.

You may want to look at the Gewiss range. I use the GW66015 and GW66004. The place at the top of a Google search seem very good.

Pete