elec. power to a garden shed

[ondro]

Hello,
I have following scenario, 20A circuit breaker in the CU. 3 x 2.5 SWA cable feed to a garden shed CU. In the shed CU I have 0.69 ohm on the income cable. On the shed are two 16A radial circuits of socket outlet. When I do Ze on the sockets , I get 2.9 ohms.
The radial circuits have 2.5mm2 flat cable no longer than 5m from the shed CU.
Any idea why is the reading so high please?

 

[telectrix]

is there a RCD in shed? this could cause a high reading if using no-trip EFLE test. try doing the test this way to eliminate the possibility. ( use the hi-current 2 lead test ).

 

[Pete999]

Hello,
I have following scenario, 20A circuit breaker in the CU. 3 x 2.5 SWA cable feed to a garden shed CU. In the shed CU I have 0.69 ohm on the income cable. On the shed are two 16A radial circuits of socket outlet. When I do Ze on the sockets , I get 2.9 ohms.
The radial circuits have 2.5mm2 flat cable no longer than 5m from the shed CU.
Any idea why is the reading so high please?

What do you mean "I have 0.69 ohms on the income cable, and Ze at the sockets"???????

 

[telectrix]

confusion with Zdb and Zs methinks, poor terminology by OP.

 

[Pete999]

confusion with Zdb and Zs methinks, poor terminology by OP.

Could be another reason though, but I'm to much of a gentleman

 

[ondro]

What do you mean "I have 0.69 ohms on the income cable, and Ze at the sockets"???????

I did Ze test in the shed CU. The result is 0.69 ohm. Then I have connected two radial circuits and did Zs test in the socket outlets. The result is 2.9 ohms

 

[ondro]

Could be another reason though, but I'm to much of a gentleman

Yes I may have poor terminology. Can you tel me what does mean Zdb please?

 

[Pete999]

Yes I may have poor terminology. Can you tel me what does mean Zdb please?

The Ze at the CU in the garage reffered to as Zdb

 

[Pete999]

I did Ze test in the shed CU. The result is 0.69 ohm. Then I have connected two radial circuits and did Zs test in the socket outlets. The result is 2.9 ohms

What is the R1+R2 of the Radial circuit??

 

[ondro]

The Ze at the CU in the garage reffered to as Zdb

OK. Thanks. So Zdb is 0.69 ohms and Zs is 2.9 ohm.
Yes an RCD is on the place.

 

[Pete999]

OK. Thanks. So Zdb is 0.69 ohms and Zs is 2.9 ohm.
Yes an RCD is on the place.

No rcd in the house then? R1+R2??

 

[telectrix]

OK. Thanks. So Zdb is 0.69 ohms and Zs is 2.9 ohm.
Yes an RCD is on the place.

then i refer you to post #2. just remember to remove the L-E short before energising.

 

[ondro]

No rcd in the house then? R1+R2??

An RCD is also in the house

 

[Pete999]

An RCD is also in the house

Not good practice to have 2 RCDs in series

 

[telectrix]

maybe it's irish... to be sure, to be sure.