Use of Wago boxes for spur

[Beeg]

Hi all,

I’m after some advice regarding use of Wago boxes for adding a spur off a ring final.

Is it okay to use a MF Wagobox with 221 Wago connectors to add a spur off of a ring?
I know the Wago 221 connectors are rated at 32A so no issues with overloading them, but the MF Wago boxes are rated at 20A - are these okay as the max current through them will be 16A (assuming load is evenly distributed around each leg of the ring), or will it be a case of 16A for the ring plus 13A for the spur = 29A?
Apologies if this is a stupid question - not too clued up on the theory and maths!
Hope this makes sense.

Thanks in advance

 

[littlespark]

Have you got a wago box, or a wago box lite, which are made for lighting connections, rather than general power.

Wago box has cable entries on just one end
Wago box light has cable entries both ends.

 

[Beeg]

Have you got a wago box, or a wago box lite, which are made for lighting connections, rather than general power.

Wago box has cable entries on just one end
Wago box light has cable entries both ends.

Hi Littlespark,
Thanks for your reply. Just checked on Screwfix and saw that the ones I have are rated at 32A… so I guess I’ve answered my own question! No idea where I got 20A from?!
It’s the Wagobox with the cable entries at just one end.

Thanks for prompting me to look properly

 

[Beeg]

Hi all,

I’m after some advice regarding use of Wago boxes for adding a spur off a ring final.

Is it okay to use a MF Wagobox with 221 Wago connectors to add a spur off of a ring?
I know the Wago 221 connectors are rated at 32A so no issues with overloading them, but the MF Wago boxes are rated at 20A - are these okay as the max current through them will be 16A (assuming load is evenly distributed around each leg of the ring), or will it be a case of 16A for the ring plus 13A for the spur = 29A?
Apologies if this is a stupid question - not too clued up on the theory and maths!
Hope this makes sense.

Thanks in advance

Sorry to keep asking questions!
Just read that wagoboxes are derated to 20A if used in a MF application… so back to my original question.

are these okay as the max current through them will be 16A (assuming load is evenly distributed around each leg of the ring), or will it be a case of 16A for the ring plus 13A for the spur = 29A?

Apologies again if this is a stupid question!
Many thanks

 

[littlespark]

How does it derate between somewhere accessible and buried under a floor?

Which begs the next question;
Does the joint have to be MF? Will it be completely inaccessible in the future?

 

[Beeg]

How does it derate between somewhere accessible and buried under a floor?

Which begs the next question;
Does the joint have to be MF? Will it be completely inaccessible in the future?

There’s a paragraph on the installation instructions specifically relating to MF.



It will be under floorboards which will be covered with laminate flooring.

 

[Lucien Nunes]

The standard rating of Wago 221-series connectors is 32A. However, to achieve the very low temperature rise specified for MF applications to BS5733, the rating is reduced to 20A. The minimum current rating for any accessory used in a ring final configured in the normal way with accessories to BS 1363 is 20A, therefore the Wago 221 / Wagobox combo can be used in MF mode for any single through or spur connection in an RFC.

All connectors dissipate some heat, and heat causes thermal movement and oxidation both of which can degrade a connection over time. The lower the temperature rise the longer its ultimate lifespan is likely to be, so if the thing is going to be inaccessible it makes sense to keep it as low as reasonably practical. The heat dissipation at 20A is about 40% of that at 32A, which evidently makes the difference between being very reliable (as Wagos are) and being so reliable they can simply be forgotten about.

 

[Beeg]

The standard rating of Wago 221-series connectors is 32A. However, to achieve the very low temperature rise specified for MF applications to BS5733, the rating is reduced to 20A. The minimum current rating for any accessory used in a ring final configured in the normal way with accessories to BS 1363 is 20A, therefore the Wago 221 / Wagobox combo can be used in MF mode for any single through or spur connection in an RFC.

All connectors dissipate some heat, and heat causes thermal movement and oxidation both of which can degrade a connection over time. The lower the temperature rise the longer the less effect it will have, so if the thing is going to be inaccessible it makes sense to keep it as low as reasonably practical. The heat dissipation at 20A is about 40% of that at 32A, which evidently makes the difference between being very reliable (as Wagos are) and being so reliable they can simply be forgotten about.

Thanks Lucien. I don’t really understand the theory of aggregate current too well, but it sounds like my proposal in the attached diagram will be okay.

Many thanks

 

[Lucien Nunes]

The point about the aggregate current is that each connection under load dissipates some heat, so the total amount of heat within the box depends both on the circuit current and the number of times the conductors pass through. If you loop the same 20A through the box, round the ring and then through another set of connections in the same box again it counts twice for total heat input.

 

[Beeg]

The point about the aggregate current is that each connection under load dissipates some heat, so the total amount of heat within the box depends both on the circuit current and the number of times the conductors pass through. If you loop the same 20A through the box, round the ring and then through another set of connections in the same box again it counts twice for total heat input.

Thanks Lucien,

So if one leg of the ring was looped through the box, plus an unfused spur, what would the aggregate current be?
Sorry to ask so many questions - I know you’ve already explained it’s okay to use for a spur but I’d just like to know the theory behind it to satisfy my own curiosity

 

[Beeg]

Thanks all for the replies. Am I looking at this in too much detail trying to calculate the aggregate current - is it simply a case of the MCB is 32A which is below the max aggregate current rating of the Wagobox of 50A when used in an MF application ?
Many thanks