'Piggy backing' tails

[digital_boy]

Hi Guys,

Came accross an install today where a new 2 way board has recently been installed to make room for a new shower circuit (Db1 - 16th edition full board).

How the 'electrician' had wired it was by using 16mm tails from DB1 main switch which now has 25mm and 16mm crammed in there (please note there are no cores cut). I no this is not the correct way but now the customer is asking which regulation this does not conform too (basically I don't think he trusts me).

The main service fuse was marked up as a 1361 type ll 60amp.

Can somebody please shine some light on this please, I don't think ill be reattending to split the tails with a henley block anytime soon

Thanks

 

[radiohead]

While I accept this sort of thing is not uncommon and even allowed in regs subject to having a fault protection capable of protecting the cable to the sub-main, the question would arise what is the main fuse? For 16mm tails let's hope it's not 100A!

The OP has stated that the 16mm tails serve a fixed load that will be under the current rating for the tails. A 100a fuse protecting a short section of tails is compliant. Overload protection can be omitted and fault protection will be adequate

 

[ipf]

I didn't say it was compliant, but if the OP is carrying out other work and the customer does not want him to remedy this, he just needs to verify that the connection shows no sign of thermal damage, and is secure and tight.....and note exactly that on his cert.
Walking away because of a relatively minor deviation from the regulations which does not form part of the work being carried out is plain daft.

If it leads to argument/disagreement/lack of trust you're better off walking away. You ridicule someone...for stating their view, without taking this into account. All situations are different but, in this one, it seems the OP is worried that there is a lack of trust.

 

[radiohead]

If it leads to argument/disagreement/lack of trust you're better off walking away. You ridicule someone...for stating their view, without taking this into account. All situations are different but, in this one, it seems the OP is worried that there is a lack of trust.

True, but there is no need for this to result in an argument or disagreement. The customer has not unreasonably asked which regulation is breached, clearly with a desire to find out why the OP considers the necessity to rectify. My opinion is that the reasons can be explained to the client, but that if there is no evidence of thermal damage or reason to suppose there may be in the future, there is no need to come over all jobsworth and walk away. No need for arguments and disagreements. If the OP is engaged in other work he notes it on his cert and states that the client was informed and declined remedial work.
I'm not surprised there is a lack of trust when the OP has condemned something as requiring rectification but is unable to give a reason other than 'it's not right'.
Just saying.

 

[ferg]

I would go with manufacturers instructions should be taken in to account. Can't remember the reg number.
Then find a pdf of the relevant MI.
Although it's R.A.F. It's something I've seen a few times with no ill effects.

 

[Lister1987]

Can't remember the reg number.
Then find a pdf of the relevant MI.
Although it's R.A.F. It's something I've seen a few times with no ill effects.

Could try and use 434.3.iv

Then advise that the DNO stipulates the tails installation be changed to meet thier requirements - may only apply to DNO tails but let's not split hairs, customer wants a reg number and you've now got one.View attachment 55793

Give the DNO a call, advise them what you can see and ask if they permit consumer tails to installed that way, if they don't then there's your deviation/breach of reg 434.3.iv.....no?

 

[Vortigern]

Overload protection can be omitted and fault protection will be adequate

I am not sure I agree we can dismiss the idea that the tails need overcurrent (as opposed to overload) protection. In terms of the fixed load ahead yes indeed but the tails at 16mm would not meet regs in the thermal destruction aspect in the case of a short. In others words what would melt first the fuse or the tails?

 

[radiohead]

I am not sure I agree we can dismiss the idea that the tails need overcurrent (as opposed to overload) protection. In terms of the fixed load ahead yes indeed but the tails at 16mm would not meet regs in the thermal destruction aspect in the case of a short. In others words what would melt first the fuse or the tails?

I do not have the BBB to hand, but it is standard practice to feed small additional DB's from a henley block in 16mm or even 10mm tails with a 100a head, 25mm into the Henley, and no downrated device. Try getting 25mm tails into a 1 way DB. The regs permit this arrangement but I cannot recall the regulation(s) that apply. I'll try and remember to look it up in the office tomorrow.

 

[westward10]

It isn't feeding a fixed load, it is a two way consumer unit.

 

[radiohead]

It isn't feeding a fixed load, it is a two way consumer unit.

The OP said it's feeding a shower, so at the time of the installation it is a fixed load. If someone else adds another circuit it is their responsibility to verify compliance for whatever they are adding.

 

[westward10]

The OP said it's feeding a shower, so at the time of the installation it is a fixed load. If someone else adds another circuit it is their responsibility to verify compliance for whatever they are adding.

He said it is a two way board which supplies the shower. The supply to this board cannot be considered a fixed load.

 

[radiohead]

He said it is a two way board which supplies the shower. The supply to this board cannot be considered a fixed load.

If the board only supplies a shower I disagree, a shower is a fixed load. But it's really irrelevant as long as the 16mm tails are of adequate CSA for the load the DB supplies. If 10mm tails were adequate they would comply. It is only the means of connection of the tails that is under question.

 

[westward10]

The shower is a fixed load but the supply to the two way board is not. I agree the 16mm conductors will be fine. Lashing them off the existing board is another matter.