I have found these practices to be good ideas:

1. The Volt Snooper brand noncontact voltage detector that I have has enough of an internal counterpoise that it is not affected by the use of insulated hot line gloves. I have also found that it works when taped to an energized conductor and I am not holding it which means that I can go over to a circuit breaker panel and find the correct breaker. Some other voltage probes will do this too but some do require contact with the human body. What we do over at International Exposition Center when having the basement crew deenergize a floor outlet for us is to stick a voltage probe into the pin and sleeve female receptacle and just wait for it to stop beeping. If we have to continuously hold a given brand in this application we put it on an unofficial list of what NOT to buy.

The only problem with the Volt Snooper is that I have to tape up the battery holder but it otherwise is a very good device.

2. Insulating shoes such as tennis shoes are also very good in dry environments which can be arranged on a construction site. Some general contractors require steel toed shoes except for the electricians who are permitted to wear tennis shoes. It still seems to be a secret as to where First Energy is buying leather shoes that are insulating and which have steel in the toes.

3. A rubber floor mat on the floor when working on energized panelboards such as when some of the branch circuits need to be energized also helps.

4. Proper design of the electrical system helps. If you need 2 42 slot panelboards to serve a given area, they should be on 2 different feeders even if you can prove that one 200 amo feeder will work. Then, the lighting circuits and receptacle circuits for each large area should come from both panelboards such that deenergizing 1 panelboard will not create total darkness or knock out all equipment. This way, you can kill all of the power in a panelboard so that installing or removing wires and circuit breakers is 100% safe. In each electrical closet there should be enough receptacles from enough different panelboards to also facilitate deenergized maintenance.

In other words, a small amount of judicious planning by the architect will make an installation safer.

5. The amount of working space that is specified for panelboards and switchgear is NOT adequate when a crew is trying to work in an under 1200 amp electrical closet. Ideally, you should have both 200% working space and 2 exits for under 1200 amp applications. Also, wire pulling is more efficient in a commercial and some industrial situations if all of the 20 amp circuits can be pulled from the electrical closet to minimize having to shlep around the wire spool cart. This is not any different than how it pays to use an oversize conduit because it saves on wire pulling labor.

Some people think that an oversize electrical closet is a waste of money but the improvement on labor efficiency when installing stuff pays for it. We also had an instance where we did not find out right before job completion that a panelboard had to be moved to comply with Americans With Disabilites access to the closet and there was no alternative location for this panelboard! I just do not see why we should have to use the cram method with electrical equipment.

A few Code cycles back somebody was kind enough to add a Fine Print Note to Chapter 9 of National Electrical Code so that we can figure out is we need to use oversize conduit such as when there are bends.

Mike Cole, mc5w at earthlink dot net