Cable reels pat testing

[McTadder]

Found two 25m cable reel extensions on a pat test yesterday with no RCDs should they be automatically taken out of service. They were at least 10 years old. The 5th addition says up to 15m max?

 

[westward10]

You can get extension reels in all sorts of length I see Screwfix selling a 45m one, from a reputable supplier. We have a rule of thumb that where the earth bond exceeds 0.18 ohm (I believe this equates to the suggested lengths in the CoP) that it is recommended it is only used with 30ma rcd protection, of course this does not take into consideration any volt drop issues.

 

[McTadder]

You can get extension reels in all sorts of length I see Screwfix selling a 45m one, from a reputable supplier. We have a rule of thumb that where the earth bond exceeds 0.18 ohm (I believe this equates to the suggested lengths in the CoP) that it is recommended it is only used with 30ma rcd protection, of course this does not take into consideration any volt drop issues.

Unwound the 25m reel was failing at 0.56 ohms. Before I started doing the maths to check !

 

[westward10]

Your tester probably has a default setting and sees the earth bond reading as too high when in fact it is just the nature of reels length.

 

[Moley]

What tester are you using? Some have settings for different length reels or a setting to put your own pass/fail value in if it's an odd length reel.

 

[McTadder]

What tester are you using? Some have settings for different length reels or a setting to put your own pass/fail value in if it's an odd length reel.

Seaward Apollo 500 + I thought there was a built in calculator but couldn’t work it out on site. Have to read the manual again?

 

[Mike Johnson]

Not very manly reading the manual, obviously in touch with your female side. ?

 

[i=p/u]

Just says it should be used with rcd, so make sure plugged into rcd protected socket or buy plug in unit..

 

[DPG]

You can't take them out of service for not having RCDs. The socket feeding them will more often than not have RCD protection.

 

[McTadder]

You can't take them out of service for not having RCDs. The socket feeding them will more often than not have RCD protection.

Are you talking about the RCD on the DB ??? They’re certainly not using a plug in RCD.

 

[i=p/u]

Either or is recommended.

 

[DPG]

Are you talking about the RCD on the DB ??? They’re certainly not using a plug in RCD.

But it's an extension lead, not a permanent bit of wiring. Can be plugged into any 13A socket.

 

[DPG]

Sorry, I've just realised the length of cable is your issue. I ignored that bit in my rush to read it. I'll dig out my code of practice and remind myself what it says.

I'm pretty sure you're right though. Isn't it over 12m they need to have a built in RCD?

Haven't got the 5th edition yet, not sure if anything has changed in that. I suspect not.

 

[i=p/u]

Says 15m and anything longer should have rcd incorporated, along them lines...

 

[Mike Johnson]

Always wondered what the red button was for. ?

 

[DPG]

It's not always the same figure. It's 12, 15 or 25m depending on csa of cable.

See table 15.4 of code of practice.

 

[DPG]

Always wondered what the red button was for. ?

To be fair a lot of the red buttons are just overload reset buttons.

 

[Mike Johnson]

To be fair a lot of the red buttons are just overload reset buttons.

I'm pretty sure that's what is on my 50m cable reel, certainly not an RCD, I think its old enough that RCD's where not available back then.

 

[pc1966]

13A fuses have Zs limit of 2.3 ohms (Table 41.2) so assuming your supply Zs is around 1 ohm at the socket then if your cable R1+R2 is 1.3 ohm or less no problem?

 

[DPG]

13A fuses have Zs limit of 2.3 ohms (Table 41.2) so assuming your supply Zs is around 1 ohm at the socket then if your cable R1+R2 is 1.3 ohm or less no problem?

They do give specific limits on length in the ISITEE code of practice though.