No earth

[Andy AC]

Today I was starting to relocate a condensing unit for a freezer room, when it came to extending the mains cable, I found that the system had no earth at all.:eek:
Earth conductor of the supply flex is used for live for solenoid valve:mad:
System has been in for about 10 years, nobody's done anything about it, so I guess I'd better do it. Presuming the cold room condenser (located next to it) has an earth, could I pick an earth up from there, or do I have to run a new one back to the control panel? which is miles away and a nasty crawl through a ceiling void.

Andy

[nike123]

I (as electrician) could live with that, bearing in mind that copper pipe which connects both indoor and outdoor unit act as earth conductor if pipes are electricaly conected with all metal parts and earth terminal with adequate clamps and conductors inside housings.

But, regulations may not tolerate that, and if something goes wrong, you will be held responsible.

[Magoo]

I go along with Nike 123, fit the new earth cable as it is your butt on the line if some one gets fried.

[nike123]

I forgot to answer question. You could connect condenser and evaporator with separate earth conductor and you don't need to go to control panel if cross section of existing earth conductor is adequate.
For example, if cross section of live wire from control panel to condenser of fridge is smaller than one which goes from control panel to condenser of freezer, than you cannot use earth wire with smaller cross section as your earthing wire for both systems.
And ,I think, here is the rule that common earth wire could not be smaller than 6mm^2 (for 230/400 V system).

[mbc]

it is better you run new wire . but if you want to save money
1- your should have earth in your system .
So , your system (condenser fan ) one phase or 3 phase .
I think should be 3 phase and connected in star so you can use O point of star for natural in all fans in condenser and Evaporators and try balancing your 3 phase Ampere to avoid unbalancing in single phase and use other wire for earth and second one for live ( do not forget to change color of wire by shrink in both side) it might be a little difficult so if I where you I run new wire.
or you can make new natural in your panal ( use In Eatrh wire for earth and make naturl wire in your panal and other one for live wire)
But if you are far from earth point how about your resistance in Earth is it right? I am not sure Please check it.

[multisync]

You must run a dedicated earth. Piggybacking off another system is not acceptable.

(If that unit is ever removed then your earthing goes with it.)

The use of copper pipe as an earth is again absolutely not acceptable. Make sure the Earth is 6mm CSA at the very least.

The earth is the most important cable. Do this right or get someone in who can.

[Andy AC]

Cheers for the input guys, I'm off to buy some cable:)
Andy

[Quality]

Dont forget that the earth suppling a circuit along side the live or lives and neutral are regarded as the circuit protective conductor not supplementary or equipotential etc.
Depending on the method of instalation the earthing of the circuit may require more than a length of earthing cable being installed if the previous earth has been used as a conductor for live or neutral as it may require a new supply cable to be installed.

PS I dont agree with nikes method

Structural steelwork Ie. pipes and extraneous conductive parts of the instalation cannot be used to supplement other parts of the electrical instalations earthing system

hope this helps

[Sledge]

As an electrician, I suggest installing a cable with a ground wire in it, and put the old cable in your truck and sell it to your next customer.

As someone else mentioned, If you try piggybacking on another ground, the ground could be lost by removal of equipment.
Trying to find another way of grounding is bad as 2 ground circuits in one building can result in potential difference between grounds...meaning one can get shocks by innocently bridging ground circuits from different parts of a building.