1mm T&E on a 16A MCB - doesn't look or feel right!

[yellowvanman]

Doing an EICR, one circuit described as Central Heating with 1 mm T&E cable connected but on a 16A MCB. When I look closer it appears an Immersion heater has been tagged onto the circuit!

I've not been able to ascertain the cable route and its installation method. This is a single storey extension, no loft space.

If I use Ref C then 1mm is OK (just). There is no signs of overheating at either end of the cable, insulation measurements are good. The immersion is probably seldom used (if at all) because of a boiler in use.

I guess I can't give it an Observation unless I chose another installation method.

Any comments/advice?

 

[westward10]

I would C2 it, you have no way of knowing its full installation method.

 

[7029 dave]

Top of my head that cable is rated at about 8amps, I would not be happy if an IH, is running off that. No way is that cable suited,dangerous IMO, would give that C2.

 

[sparkdog]

I once found some 13A sockets wired in 1mm T&E.

 

[polo1]

Yep, C2!

 

[buzzlightyear]

I would agree with westward c2 on test sheet on observation sheet
c/heating cable needs lower rating of mcb & should not be on that circuit

 

[yellowvanman]

For your information 1.0mm T&E with Reference Method C is 16A

 

[davesparks]

Top of my head that cable is rated at about 8amps, I would not be happy if an IH, is running off that. No way is that cable suited,dangerous IMO, would give that C2.

Actually it can be rated at twice that, depending on all the usual factors

 

[7029 dave]

For your information 1.0mm T&E with Reference Method C is 16A

It all surface wiring then.?

 

[westward10]

How do you be sure it is clipped direct throughout.

 

[Ian1981]

If it's only feeding a central heating system then if it's connected through a switch fused spur the cable on the load side will be fused down to 3amps hopefully.
It will never pull 16amps so overload protection can be omitted plus the 3amp fuse will provide protection to the outgoing cable to the boiler.
If it's powering an immersion heater than yeah , wouldn't be happy with 16amp mcb feeding 1mm.
Cable is rated to 16amps clipped direct tho.

 

[7029 dave]

Well even if it was clipped direct through out, I would not be happy with that size cable.

 

[Ian1981]

Well even if it was clipped direct through out, I would not be happy with that size cable.

I Agree with you

 

[yellowvanman]

How do you be sure it is clipped direct throughout.

I'm not, but I can't assume anything either way.

I was already to make it a C2 until the software I used highlighted that 1mm T&E using Ref C was ok!

 

[Ian1981]

Think the norm is installing 2.5mm from db on 16amp mcb through a double pole switch and 1.5mm heat resistant flex out into immersion element

 

[westward10]

C2 it, ignore the software.

 

[Ian1981]

To be fair as well a typical immersion heater is 3000 watts so pulls 13amps.
The 16amp mcb won't need to provide overload protection to a fixed load so will only need to protect the cable for fault protection purposes.

 

[yellowvanman]

I know I shouldn't be worrying about a solution, but the easiest way to resolve is to put the immersion on the ring! I do realise that its not recommended (not prohibited though) but as its not used much (if at all) I think this should be OK.

 

[Ian1981]

Table 52.3 in bs 7671 does say that power circuits are to be wired in 1.5mm as a minimum or for a specific appliance is specified by the product standard so depends on manufacturers instructions as well

 

[yellowvanman]

Table 52.3 in bs 7671 does say that power circuits are to be wired in 1.5mm as a minimum or for a specific appliance is specified by the product standard so depends on manufacturers instructions as well

That I think clinches my dilemma - C2 it is!