Economy 7 board and live testing

[Gavin John Hyde]

Got a job and cant do live testing as the old fuse box is economy 7 with those plugin wylex mcbs replacing the rewireables. Only changing over a heater and replacing a stretch of damaged flex.

Cant do any live testing due to board being dead during sensible hours. The installation is of such an age I would not want to risk linking over live tails from one board to another to get power to it, pulling fuse is no go as its as old as everything else in flat. not that we ever pull these things mind!
Irony being the main fuse board is fed from newish digital meter but they didnt put in an isolator. the economy 7 meter is a old glass box with metal dials inside! i cant put heater on the other baord as no capacity for another circuit. I should have taken pictures. I have suggested new CU, if only for the rcd protection it brings.
Any ideas on how to test it apart from going back out later in evening? there is no rcd protection so heater flex will be surface mounted clipped to skirting board. I am repairing a bit of damaged flex and adding the new heater. nothing too grand.

 

[Octopus]

Could you not run a temporary supply from the 24/7 CU to the E7 board and take some Zs readings?

Or just use "LIM" a lot?

 

[Strima]

Do your dead tests. Ze at the incomer and an explanation on the cert as to why live testing could not be carried out.

 

[Dave OCD]

Well you don't have to do RCD testing so I'd use the Ze from the 'normal' board & measured R1+R2 from your new supply cable to get the Zs.

 

[westward10]

Liven it up or get there early morning for the tests.

 

[Gavin John Hyde]

As @daveocd said, i did consider calculating the Zs and taking the PFC, PSCC etc from other board, the Ze is good on other board.
I am wary off linking some cables over from the peak to off peak board. sadly the type of switch in them means i cant realistically get a cable in the outgoing as they are cooper busbars rather than cables, otherwise i would have flicked off, put in a bit 0f 16mm and looped over to the other board. Looking at it though the screws in the incomer hasnt been touched since install in the 80s.

 

[westward10]

Length of wire with croc clip one end. Remove one fuse shield from the Wylex standard board and connect croc clip to busbar then connect to mcb at other board. Switch off the off peak board, link its neutral and earth bars and away you go

 

[robd]

I would just do all the dead test and put a note on there to say why you couldn't test it. Personally.

 

[Gavin John Hyde]

I would just do all the dead test and put a note on there to say why you couldn't test it. Personally.

Guess its a cover your backside unless i can gain access during afterhours so to speak, guess its one up on a diy bang test.

 

[westward10]

What is the world coming to, liven it up.

 

[Toneyz]

Apart from the dead tests for the circuit and going back when power is on, you could take Ze from the 24hr C.U. take main earth out and do a continuity test. With the main switch off and if TNC-S you could prove neutral assuming live only is switched in the meter.

 

[Gavin John Hyde]

What is the world coming to, liven it up.

elf and safeity these days! with newer stuff i would be more willing but a lot of the terminals on these old fuse boards have not ben touched since install. they are on tight and theres a good chance if i start undoing things when live that bad things might happen, so i keep it safe and live another day.

 

[westward10]

No need to loosen any terminals see #7.

 

[davesparks]

Just use the alternative Zs test method, no need to liven up the board that way.

Switch off the main switch of the E7 board.
Link L-E at the furthest point on the circuit to be tested.
With the mcb for that circuit closed loop test with the L probe on the live tail of the 24hr board and the E probe on the busbar of the E7 board.

This method was used before the majority of testers incorporated anti-trip/low current testing. It tests the same circuit as a standard Zs test, the only difference is the test instrument being in a different part of the circuit.

The only thing you miss out with this method is the L tail in to the E7 board.