Hi guys, new member here needing advice on workshop wiring.

[westward10]

It sounds as if the cable doesn't require additional rcd protection assuming fault protection is provided without it, joints or no joints. A metallic bench is not likely to require an earth and by supplementary bonding I assume you mean main protective bonding to any services if required.

 

[Martin Turner]

My house CB was changed and inspected Sep 2010 so the original 10mm cable would have been inspected then. There is going to be one join in the 10mm cable to add length to get it into the work shop but the original shower cable going through a shower isolator would have had two joins if you look at it like that.

All the cables in the workshop will be either clipped to roof joists, walls etc and then the drops in plastic conduit.

The bench may be used for TIG welding so I don't know how that would affect it if it was earthed?, I have worked in the rail and marine industry for a while and to be honest I have never seen work benches earthed before unless it's for high charged electrical/ static repairs etc.

We have a couple of sparks at work that may still be registered outside so I could get them to do a test and inspect once it's all done.

Thanks for the advice so far.

 

[Pete999]

It sounds as if the cable doesn't require additional rcd protection assuming fault protection is provided without it, joints or no joints. A metallic bench is not likely to require an earth and by supplementary bonding I assume you mean main protective bonding to any services if required.

No I mean supplementary bonding, if any water, gas, compressed air lines etc I would expect the main protective will already be in place, do well to check though.

 

[Martin Turner]

I can't remember seeing bonding at our stopcock but I know the gas is 10mm.
Only pipework in the workshop will be comp air via a fixed hose reel and that will probably be fed from the compressor in plastic.

 

[Pete999]

I can't remember seeing bonding at our stopcock but I know the gas is 10mm.
Only pipework in the workshop will be comp air via a fixed hose reel and that will probably be fed from the compressor in plastic.

The video will explain how to test to see if the air line requires bonding

 

[adamgaskin]

If the joint will be inside the building somewhere then you shouldn't really have an issue. Maybe I'm talking pish here but I was always taught to bond any large extraneous conductive parts i.e the bench as a bit of belt and braces. For example if the earthing on the welder fails then the next available fault path is through the bench into you. But then that being said if your using plastic conduit then there will be nothing to bond it to other than the welder supply or the next bit of equipment or a daisy chain back to the CU

 

[adamgaskin]

just watched that video, kinda answers my question to be honest cheers.

 

[Pete999]

If the joint will be inside the building somewhere then you shouldn't really have an issue. Maybe I'm talking pish here but I was always taught to bond any large extraneous conductive parts i.e the bench as a bit of belt and braces. For example if the earthing on the welder fails then the next available fault path is through the bench into you. But then that being said if your using plastic conduit then there will be nothing to bond it to other than the welder supply or the next bit of equipment or a daisy chain back to the CU

Have you tested any of the extraneous parts to determine if they rquire bonding?

 

[Martin Turner]

I will check my stop cocks as its on the same side of my house as the CB so I could run in a 10mm earth if required, the work bench will be wood and may have a sheet of metal at one end for welding, the only other fixed metal machines will be a small lathe and mill but they will be earthed through there isolators.

 

[Toneyz]

I don't know how we came onto the subject of running in 10mm earth cables into the workshop. You state that there is no pipework in the workshop the comp.air will probably be plastic and the workbench is wooden it is unlikely that the metal screen will be a extraneous conductive part. Regarding bonding what needs to be checked is the existing services (gas & water) are bonded this you could do visually and check with the electrical contractor who issued the certificate when you had the consumer unit changed this should of been inspected and tested at this time. Also can the existing installation take this additional load. I f the existing cable is all run surface I would move onto non protected side and install a RCD main switch consumer unit in the workshop. Make sure that the cable in the loft is clipped above the insulation so it does not have to be de-rated.

 

[westward10]

Pesky rats.

 

[Toneyz]

Pesky rats.

The OP didn't say he had a rodent problem.

 

[westward10]

The OP didn't say he had a rodent problem.

Avin a jest see the last word of your post

 

[Toneyz]

Avin a jest see the last word of your post

Very good well spotted.

 

[Martin Turner]

I didn't write that clearly in my previous post about the 10mm Earth, I meant to my stop
cock.

The original installation should be ok as the original shower had this 40A supply and the max rated socket in the workshop will now be only 32A, this socket may never get used anyway as my current TIG welder uses a 16A supply but if I ever upgrade the welder I may buy a 32A water cooled TIG next hence the reason I want this socket.

Some of you have said put the 10mm supply cable on the non protected side of my house CB and fit a RCD/MCB CB in my workshop but then the supply cable between both CB's won't be RCD protected?, does it need RCD protecting in my loft?.
I appreciate you won't get any nuisance tripping of the house if it's wired this way as the RCD will be in the workshop.

 

[westward10]

See #13 as rcd protection may not be necessary.

 

[Martin Turner]

This is your post:-

If any part of it is buried in a wall at a depth of less than 50mm and without earthed containment it requires additional rcd protection. If this is not the case and fault protection can be maintained without the use of an rcd then you can omit rcd protection.

Mine is run up the outside wall in plastic conduit and clipped through my loft space so needs RCD protection then ?

 

[Toneyz]

This is your post:-

If any part of it is buried in a wall at a depth of less than 50mm and without earthed containment it requires additional rcd protection. If this is not the case and fault protection can be maintained without the use of an rcd then you can omit rcd protection.

Mine is run up the outside wall in plastic conduit and clipped through my loft space so needs RCD protection then ?

From what you describe no. Where does it go from the loft straight through into this new workshop roof ?.

 

[westward10]

From what you say it doesn't but your earthing system will be a factor and if not TT, which would require an rcd for fault protection then a test is required to ensure an mcb without rcd protection would provide fault protection.

 

[Martin Turner]

I will check my earthing type but I think it's either TNS or TNCS.
Regarding the 10mm cable it runs through my loft space and where it connected to the original shower isolator it will be now going into a junction box and connecting to a black round double insulated 10mm 3 core cable that runs to the workshop.
As my workshop is only 3.4M the black 10mm will be dropped through my soffit and clipped to the house wall for approx 1.5M's before it goes into the workshop.