Electrical test on D.O.L fed straight from main panel isolator

Yanman · Sep 28, 2022

Hello everyone

i recently got a job on replacing a BMS panel in a plant room. the NEW panel i installed except the control side of the install also feeds the mains for a few gas boilers, immersion heaters and cylinders, pumps. etc. I am going to do the testing on that and i realised that some of the D.O.L circuits in the panel are is not fed from a MCB but are connected straight to the isolator that is fed from the main DB. meaning that the only for of protection on the D.O.L is the 50A mcb that feeds the panel.

now up to the D.O.L circuits the wirings is done with 10mm singles and on the outgoing side with lower rating cores depending the rating.

is that acceptable and if how do i record the DOL on my EICR?

i am New to testing as well so i don't have a lot of experience specially when it comes on BMS panels

snowhead · Sep 28, 2022

Are you certain these circuits are connected directly, have you missed anything?
I've worked on hundreds of BMS panels and never seen any circuit without suitable protection.

Yanman · Sep 28, 2022

snowhead said:
Are you certain these circuits are connected directly, have you missed anything?
I've worked on hundreds of BMS panels and never seen any circuit without suitable protection.

Yes most positive. i physically traced the cables going to the main isolator, and i also have it on the drawings. thats the picture of it and basically is as shown on the drawings

[ElectriciansForums.net] Electrical test on D.O.L fed straight from main panel isolator

davesparks · Sep 28, 2022

Assuming these DOL starters include overload protection then I dont see any technical issue.
The 10mm singles should have adequate fault protection from the 50A MCB and overload protection is provided by the overloads on the DOL.

Yanman · Sep 28, 2022

davesparks said:
Assuming these DOL starters include overload protection then I dont see any technical issue.
The 10mm singles should have adequate fault protection from the 50A MCB and overload protection is provided by the overloads on the DOL.

Yes they do have overload protection.
Electrically i don't see something wrong aswell but then how do i record this on the test sheet where i usually have the type of the mcb rating etc get max ZS permitted and everything.

WallaceP · Sep 29, 2022

check OL manufacture for spec for Max earth loop,
for each motor do a new circuit.

Yanman · Sep 29, 2022

So I did a bit of research online and I found that the motor starter that is used is in accordance with iec 60947-4-1 . I will have to calculate the max zs through the equation from the info thats provided in the starter datasheet.

davesparks · Sep 29, 2022

Yanman said:
Yes they do have overload protection.
Electrically i don't see something wrong aswell but then how do i record this on the test sheet where i usually have the type of the mcb rating etc get max ZS permitted and everything.

Find out the max Zs and record each one as a new circuit.

Or else create your own record of test results that is better suited to the type of installation.

Yanman · Sep 30, 2022

davesparks said:
Find out the max Zs and record each one as a new circuit.

Or else create your own record of test results that is better suited to the type of installation.

Yeah that's what I did in the end. I got data sheet from the manufacturer and calculated the max Zs for each of them.